Michael Thompson

Turtles ( Chelodina longicollis ) regulate muscle metabolic enzyme activity in response to seasonal variation in body temperature

Publisher: Springer Science and Business Media LLC

Date: 04-2004

DOI: 10.1007/S00360-003-0331-2

Abstract: Fluctuations in the thermal environment may elicit different responses in animals: migration to climatically different areas, regulation of body temperature, modification of biochemical reaction rates, or assuming a state of dormancy. Many ectothermic reptiles are active over a range of body temperatures that vary seasonally. Here we test the hypothesis that metabolic enzyme activity acclimatises seasonally in freshwater turtles (Chelodina longicollis) in addition to, or instead of, behavioural regulation of body temperatures. We measured body temperatures in free-ranging turtles (n = 3) by radiotelemetry, and we assayed phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS) and cytochrome c oxidase (CCO) activities in early autumn (March, n = 10 turtles), late autumn (May, n = 7) and mid-winter (July, n = 7) over a range of assay temperatures (10 degrees C, 15 degrees C, 20 degrees C, 25 degrees C). Body temperatures were either not different from, or higher than expected from a theoretical null-distribution of a randomly moving animal. Field body temperatures at any season were lower, however, than expected from animals that maximised their sun exposure. Turtles maintained constant PFK, LDH and CCO activities in different months, despite body temperature differences of nearly 13.0 degrees C between March (average daily body temperature = 24.4 degrees C) and July (average = 11.4 degrees C). CS activity did not vary between March and May (average daily body temperature = 20.2 degrees C), but it decreased in July. Thus C. longicollis use a combination of behavioural thermoregulation and biochemical acclimatisation in response to seasonally changing thermal conditions. Ectothermic reptiles were often thought not to acclimatise biochemically, and our results show that behavioural attainment of a preferred body temperature is not mandatory for activity or physiological performance in turtles.

The ethological trap: functional and numerical responses of highly efficient invasive predators driving prey extinctions

Publisher: Wiley

Date: 20-09-2016

DOI: 10.1002/EAP.1375

Abstract: Ecological traps are threats to organisms, and exist in a range of biological systems. A subset of ecological trap theory is the "ethological trap," whereby behaviors canalized by past natural selection become traps when environments change rapidly. Invasive predators are major threats to imperiled species and their ability to exploit canalized behaviors of naive prey is particularly important for the establishment of the predator and the decline of the native prey. Our study uses ecological theory to demonstrate that invasive predator controls require shifts in management priorities. Total predation rate (i.e., total response) is the product of both the functional response and numerical response of predators to prey. Functional responses are the changes in the rate of prey consumption by in idual predators, relative to prey abundance. Numerical responses are the aggregative rates of prey consumption by all predators relative to prey density, which change with predator density via reproduction or migration, in response to changes in prey density. Traditional invasive predator management methods focus on reducing predator populations, and thus manage for numerical responses. These management efforts fail to manage for functional responses, and may not eliminate impacts of highly efficient in idual predators. We explore this problem by modeling the impacts of functional and numerical responses of invasive foxes depredating imperiled Australian turtle nests. Foxes exhibit exceptionally efficient functional responses. A single fox can destroy >95% of turtle nests in a nesting area, which eliminates juvenile recruitment. In this case, the ethological trap is the "Arribada" nesting strategy, an emergent behavior whereby most turtles in a population nest simultaneously in the same nesting grounds. Our models show that Arribada nesting events do not oversaturate foxes, and small numbers of foxes depredate all of the nests in a given Arribada. Widely scattering nests may reduce fox predation rates, but the long generation times of turtles combined with their rapid recent decline suggests that evolutionary responses in nesting strategy may be unlikely. Our study demonstrates that reducing populations of highly efficient invasive predators is insufficient for preserving native prey species. Instead, management must reduce in idual predator efficiency, independent of reducing predator population size.

Placental nutrition in the Tasmanian skink, Niveoscincus ocellatus

Publisher: Springer Science and Business Media LLC

Date: 26-02-2001

DOI: 10.1007/S003600000166

Abstract: Niveoscincus ocellatus is an important species in historical analyses of the evolution of viviparity because it is the species upon which the type II chorioallantoic placenta was based. Here we describe the net nutrient uptake across the placenta of N. ocellatus for comparison with other species of skinks with complex placentae. N. ocellatus is highly placentotrophic, with neonates being 1.68-times larger in dry matter than the fresh eggs. There is an increase of nitrogen from 6.3 +/- 0.2 mg to 9.2 +/- 0.6 mg, and ash from 3.8 +/- 0.3 mg to 6.7 +/- 0.6 mg. The increase in ash is made up by a more than two-fold increase in the amounts of calcium, potassium and sodium. There is no significant difference in lipids in the neonates compared to fresh eggs, so considerable lipid must have crossed the placenta to provide energy for embryonic development. N. ocellatus is significantly more placentotrophic than Niveoscincus metallicus, which also has a complex chorioallantoic placenta. Discovery of substantial placentotrophy in this genus confirms that two lineages of Australian lygosomine skinks (represented by the genera Pseudemoia and Niveoscincus) have evolved this pattern of embryonic nutrition and supports the hypothesis that the evolution of reptilian placentotrophy involves specialisations in addition to structural modifications of the chorioallantoic placenta.

Placentation in the Eastern Water Skink (Eulamprus Quoyii): A Placentome-Like Structure in a Lecithotrophic Lizard

Publisher: Wiley

Date: 24-03-2011

DOI: 10.1111/J.1469-7580.2011.01368.X

Prey protein influences growth and decoration building in the orb web spider Argiope keyserlingi

Publisher: Wiley

Date: 09-09-2009

DOI: 10.1111/J.1365-2311.2009.01095.X

Cyto-epitheliochorial placenta of the viviparous lizard Pseudemoia entrecasteauxii: a new placental morphotype.

Publisher: Wiley

Date: 2005

DOI: 10.1002/JMOR.10314

Abstract: The structural features of the uterine epithelium of the chorioallantoic placenta and omphalloplacenta in the viviparous Australian skink, Pseudemoia entrecasteauxii, were investigated using SEM and TEM techniques. In particular, the structural characteristics that would allow interpretation of function were analyzed, particularly those of gas exchange in the chorioallantoic placenta and histotrophy in the omphaloplacenta. Pseudemoia entrecasteauxii has a complex placenta consisting of a placentome, paraplacentome, and omphaloplacenta. The paraplacentome has a well-vascularized lamina propria in which projecting uterine capillaries displace the overlying uterine epithelial cells, reducing them to attenuated cytoplasmic extensions. Associated cell nuclei and organelles are lost from this region, to provide a capillary lumen to uterine lumen barrier of 0.5-1.0 microm. Hence, the paraplacentome is likely a prominent site for gaseous exchange via simple diffusion. The omphaloplacenta has a similar cytology to that of the placentome, but the uterine epithelial cells are hypertrophied and the apical plasma membrane actively secretes vesicles into the uterine lumen. The omphaloplacenta shows features that are associated with histotrophic transport of nutrients via vesicle secretion, very similar to that of lipid apocrine secretion. The placentome consists of cuboidal cells in the uterine epithelium, with large centrally located nuclei overlying the well-vascularized lamina propria. Although the placentome has a similar cytological structure to that of the omphaloplacenta, granules or active vesicle secretion were not observed. Thus, the placentome may be associated with histotrophy, but not via apocrine secretion. Squamate placentation is epitheliochorial however, we propose a new term be used to describe the type of placentation in P. entrecasteauxii: "cyto-epitheliochorial," because of the extreme attenuation of uterine epithelial cells of the paraplacentome.

Uterine gene expression in the live-bearing lizard, Chalcides ocellatus, reveals convergence of squamate reptile and mammalian pregnancy mechanisms

Publisher: Oxford University Press (OUP)

Date: 2012

DOI: 10.1093/GBE/EVS013

Uterine and chorioallantoic angiogenesis and changes in the uterine epithelium during gestation in the viviparous lizard, Niveoscincus conventryi (Squamata: Scincidae)

Publisher: Wiley

Date: 15-08-2012

DOI: 10.1002/JMOR.11002

Abstract: We used immunofluorescent confocal microscopy and scanning electron microscopy to quantify uterine vascularity and to describe uterine surface morphology during gestation in pregnant females of the lecithotrophic lizard Niveoscincus coventryi. As uterine angiogenesis and epithelial cell morphology are thought to be under progesterone control, we studied the effect of a progesterone receptor antagonist (mifepristone) on uterine and chorioallantoic microvasculature and features of the uterine epithelial surfaces. Although intussuceptive angiogenesis was observed in both, uterine and chorioallantoic, vascular beds during gestation, the only significant increases were in the diameters of the uterine vessels. An ellipsoid vessel-dense area grows in the mesometrial hemisphere of the developing conceptus, which parallels the expansion of the allantois to form the chorioallantoic placenta. Uterine surface topography changed during gestation. In particular, uterine blood vessels bulge over the luminal surface to form marked ridges on the uterine embryonic hemisphere, especially during the last stage of pregnancy, and ciliated cells are maintained in the embryonic and abembryonic hemispheres but disappear in both the mesometrial and antimesometrial poles. This distinct regionalization of uterine ridges and ciliated cells in the uterine surface and in the shape of the epithelial component of the chorion might be related to the function of both chorioallantoic and yolk sac placentae during gestation. There was no significant difference between females treated with or without mifepristone, which may be related to the partial function of mifepristone as a progestin antagonist and/or with the function and time of action of progesterone in the uterus during gestation in N. coventryi. Differences in the pattern of angiogenesis and uterine surface morphology during gestation among squamates may be related to the functional ersity of the uterine component of the different placentae and probably reflect its erse evolutionary history.

Phenotypic flexibility in the metabolic response of the limpet Cellana tramoserica to thermally different microhabitats

Publisher: Elsevier BV

Date: 07-2006

DOI: 10.1016/J.JEMBE.2006.03.010

Thyroid Hormones Reduce Incubation Period without Developmental or Metabolic Costs in Murray River Short-Necked Turtles (Emydura macquarii)

Publisher: University of Chicago Press

Date: 2017

DOI: 10.1086/689744

Abstract: Metabolic processes are affected by both temperature and thyroid hormones in ectothermic vertebrates. Temperature is the major determinant of incubation length in oviparous vertebrates, but turtles can also alter developmental rate independent of temperature. Temperature gradients within natural nests cause different developmental rates of turtle embryos within nests. Despite temperature-induced reductions in developmental rate, cooler-incubated neonates often hatch synchronously with warmer siblings via metabolic compensation. The physiological mechanisms underlying metabolic compensation are unknown, but thyroid hormones may play a critical role. We applied excess triiodothyronine (T

The tight junctional protein occludin is found in the uterine epithelium of squamate reptiles

Publisher: Springer Science and Business Media LLC

Date: 27-07-2007

DOI: 10.1007/S00360-007-0192-1

Abstract: Occludin, an integral protein associated with the mammalian tight junction, has for the first time been identified in the uterus of squamate reptiles. The tight junction is made up of anastamosing strands and forms a selective barrier that regulates paracellular diffusion of solutes across uterine epithelium. Occludin exclusively labels tight junctional strands and is an excellent marker for tight junction permeability. Using western blotting and immunohistochemistry, occludin expression was examined in the uterine epithelium of five species of Australian skinks at different stages of gestation. More occludin was detected during late stage pregnancy/gravidity compared to the lower levels of occludin detected in vitellogenic and post-parturient females in three of the five species. We conclude that the paracellular permeability of the squamate uterine epithelium decreases as gestation progresses. As placental transport of ions and solutes to the embryo is highest during the last third of pregnancy in viviparous squamates, it is likely that a decrease in paracellular permeability is compensated by an upregulation of other transporting mechanisms such as histotrophy.

Expression of VEGF 111 and other VEGF-A variants in the rat uterus is correlated with stage of pregnancy

Publisher: Springer Science and Business Media LLC

Date: 08-10-2016

DOI: 10.1007/S00360-016-1040-Y

Abstract: Vascular endothelial growth factor A is a major mediator of angiogenesis, a critically important process in vertebrate growth and development as well as pregnancy. Here we report for the first time the expression of a rare and unusually potent splice variant, VEGF

Biology of the invasive delicate skink (Lampropholis delicata) on Lord Howe Island

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/ZO14098

Abstract: Lord Howe Island (LHI) is a remote oceanic island in the south-west Pacific that is World Heritage listed due to its erse, and largely endemic, biota. A suite of introduced species have colonised the island, resulting in the widespread population declines of many native species. The delicate skink (L ropholis delicata DeVis) was accidentally introduced to LHI from mainland eastern Australia, but there has been no detailed investigation of its biology on the island, or its potential impact on the native biota. We conducted a detailed study of the distribution and biology of the delicate skink on LHI over a six-year period (2007–12). The delicate skink was introduced to LHI in the 1980s, and rapidly spread across the island. It presently occurs in all 21 low-elevation vegetation communities on LHI. The delicate skink is diurnal on LHI, and displays seasonal variation in activity with a peak in November–December. The delicate skink exhibits sexual dimorphism with females having larger body and abdomen sizes and males having longer and broader heads, although the degree of genetic admixture may influence morphology on LHI. Females reproduce in spring and summer (September–February), with a positive relationship between body size and clutch size. Clutch size ranges from 1 to 7 (mean 3.4) and communal egg nests (11–200+ eggs) are common. Tail loss is common on LHI (55%), but is more frequent in adults and females. We conclude that, based on its distribution and abundance, the delicate skink has the potential to impact the erse and endemic invertebrate fauna on LHI.

Biogeographic barriers in south-eastern Australia drive phylogeographic divergence in the garden skink, Lampropholis guichenoti

Publisher: Wiley

Date: 17-05-2011

DOI: 10.1111/J.1365-2699.2011.02531.X

The significance of predation in nest site selection of turtles: an experimental consideration of macro‐ and microhabitat preferences

Publisher: Wiley

Date: 08-2003

DOI: 10.1034/J.1600-0706.2003.12436.X

Seasonal sex ratios and the evolution of temperature-dependent sex determination in oviparous lizards

Publisher: Springer Science and Business Media LLC

Date: 23-01-2016

DOI: 10.1007/S10682-016-9820-0

Sex steroids influence the plasma membrane transformation in the uterus of the fat-tailed dunnart (Sminthopsis crassicaudata, Marsupialia)

Publisher: CSIRO Publishing

Date: 2019

DOI: 10.1071/RD18202

Abstract: The uterine epithelium undergoes remodelling to become receptive to blastocyst implantation during pregnancy in a process known as the plasma membrane transformation. There are commonalities in ultrastructural changes to the epithelium, which, in eutherian, pregnancies are controlled by maternal hormones, progesterone and oestrogens. The aim of this study was to determine the effects that sex steroids have on the uterine epithelium in the fat-tailed dunnart Sminthopsis crassicaudata, the first such study in a marsupial. Females were exposed to exogenous hormones while they were reproductively quiescent, thus not producing physiological concentrations of ovarian hormones. We found that changes to the protein E-cadherin, which forms part of the adherens junction, are controlled by progesterone and that changes to the desmoglein-2 protein, which forms part of desmosomes, are controlled by 17β-oestradiol. Exposure to a combination of progesterone and 17β-oestradiol causes changes to the microvilli on the apical surface and to the ultrastructure of the uterine epithelium. There is a decrease in lateral adhesion when the uterus is exposed to progesterone and 17β-oestradiol that mimics the hormone environment of uterine receptivity. We conclude that uterine receptivity and the plasma membrane transformation in marsupial and eutherian pregnancies are under the same endocrine control and may be an ancestral feature of therian mammals.

Utilisation of nutrients by embryos of the enigmatic Australian viviparous skinkNiveoscincus coventryi

Publisher: Wiley

Date: 2001

DOI: 10.1002/JEZ.1059

Abstract: The Eugongylus species group of Australian lygosomine skinks provides an unparalleled opportunity to study the evolution of placentotrophy. Viviparity and placentotrophy have evolved in two lineages, currently recognised as the genera Pseudemoia and Niveoscincus. The genus Niveoscincus is important because it is the only lineage of squamates in which variation in placental morphology and in the pattern of embryonic nutrition is known. Niveoscincus coventryi has the least complex placental morphology among species currently assigned to the genus. We quantified the net uptake of nutrients across the placenta of N. coventryi for comparison with other species in the genus and with other viviparous and oviparous lizards. The pattern of embryonic nutrition of N. coventryi is similar to other viviparous lizards with simple placentae in that there is no net uptake of dry matter during development but there is a net uptake of water, calcium, potassium, and sodium. There is no net uptake of lipid, nitrogen (an index of protein), or magnesium. We conclude that N. coventryi is predominantly lecithotrophic. Further, if N. coventryi is the sister taxon to Tasmanian Niveoscincus, then the distribution of patterns of embryonic nutrition among members of this clade suggests that the evolution of placentotrophy occurred during radiation of this lineage in Tasmania.

Biochemical acclimation of metabolic enzymes in response to lowered temperature in tadpoles of Limnodynastes peronii

Publisher: Elsevier BV

Date: 04-2004

DOI: 10.1016/J.CBPB.2004.02.008

Changes In Oviductal Morphology Of The Skink, Lampropholis Guichenoti, Associated With Egg Production

Publisher: Wiley

Date: 2004

DOI: 10.1002/JMOR.10262

Abstract: We describe changes in the morphology of the oviductal epithelium of an oviparous skink, L ropholis guichenoti, during the course of egg production and oviposition: to characterize the luminal epithelial changes to provide a baseline for understanding uterine changes in viviparous species and to establish whether the plasma membrane transformation of uterine epithelial cells is indeed a feature restricted to viviparous species. Oviducts from vitellogenic, gravid, and postgravid females were observed using scanning electron microscopy. Cellular characteristics of the oviductal epithelium previously used to determine the plasma membrane transformation were assessed morphologically. Three anatomically different areas were defined within the oviduct, but no plasma membrane transformation was observed in the oviparous skink, suggesting that this is a phenomenon particular to viviparity.

Lysosomal and alkaline phosphatase activity indicate macromolecule transport across the uterine epithelium in two viviparous skinks with complex placenta

Publisher: Wiley

Date: 15-12-2009

DOI: 10.1002/JEZ.B.21297

Abstract: In addition to water and small inorganic ions, macromolecules traverse the uterine epithelium in viviparous skinks to be absorbed by the developing fetus. In some species of lizards with complex placenta, the paracellular pathway across the uterine epithelium becomes tighter and more highly regulated as gestation progresses, suggesting that the transcellular pathway may be an alternative route for molecules to travel across the epithelium. In this study, we identified an extensive formation of a lysosomal system in the apical region of uterine epithelial cells in the highly secretory omphaloplacental region of the skink placenta in two species from the Pseudemoia genus. We suggest that this lysosomal system assists apocrine secretion by digesting large macromolecules into smaller particles, allowing more effective transport across the plasma membrane of uterine epithelial cells. We also demonstrate alkaline phosphatase (AP) activity along the apical plasma membrane of uterine epithelial cells in the omphaloplacental region of skink uterus, an enzyme usually associated with active transport in secretory cells. Apocrine secretion, an extensive lysosomal system and AP activity, offer strong evidence that macromolecules are transported across uterine epithelium of the omphaloplacenta. Our study is the first to provide histochemical evidence of macromolecular transport across this region of the placenta in two species of skinks from the genus with the most complex placenta described in Australia.

Comparison of the fatty-acid compositions of prey items and yolks of Australian insectivorous scincid lizards

Publisher: Springer Science and Business Media LLC

Date: 14-04-2004

DOI: 10.1007/S00360-004-0425-5

Abstract: The yolk fatty-acid profiles of a range of species of insectivorous scincid lizards generally conform to a common pattern, typified by high proportions of linoleic acid (13.5-18.5% of total fatty acids), substantial proportions of alpha-linolenic acid (2.4-8.2%), and significant amounts of the long-chain polyunsaturated fatty acids, arachidonic (1.6-3.3%), eicosapentaenoic (0.7-1.2%) and docosahexaenoic (0.7-1.6%) acids. We characterised the fatty-acid compositions of ten prey taxa that are eaten by female skinks during vitellogenesis. Linoleic acid is the major polyunsaturated fatty acid in all prey, excepting Orthoptera where alpha-linolenic acid predominates. To varying extents, alpha-linolenic acid is present in all the prey items. Arachidonic acid forms over 1% of total fatty acids for six of the prey items. Four of the prey items contain eicosapentaenoic acid at over 1%. Most notably, docosahexaenoic acid is essentially absent from all the prey items. There is a general similarity between the fatty-acid profiles of prey and yolk, suggesting that the linoleic, alpha-linolenic, arachidonic and eicosapentaenoic acids required for egg formation can be supplied directly from the maternal diet. However, the docosahexaenoic acid of the egg lipids cannot derive from the diet and must, therefore, be formed by biosynthesis in the maternal liver, using dietary alpha-linolenic and eicosapentaenoic acids as precursors.

Nocturnal lizards from a cool-temperate environment have high metabolic rates at low temperatures

Publisher: Springer Science and Business Media LLC

Date: 18-06-2010

DOI: 10.1007/S00360-010-0489-3

Abstract: Ectotherms from low-temperature environments have higher metabolic rates at low temperatures than those from warm-temperature environments. We predicted that nocturnal lizards, which are active at much lower environmental temperatures than diurnal lizards, would also have higher metabolic rates at low temperatures, and by association a lower thermal sensitivity (Q(10)) than diurnal and crepuscular lizards. We measured the rate of oxygen consumption (VO2) of eight cool-temperate species of lizard (four nocturnal, three diurnal, and one crepuscular) at 13 and 26°C and analyzed log transformations of these data using log mass as a covariate. As expected, VO2 was positively correlated with temperature in all eight species, with VO2 being two to four times higher at 26°C than at 13°C. As predicted, at 13°C (but not 26°C) the VO2 was significantly higher in nocturnal than diurnal lizards. Species-specific differences and mass scaling factors explain the patterns of thermal sensitivity seen among these eight lizard species. Thermal sensitivity is strongly influenced by mass, with smaller species generally having higher thermal sensitivity of their metabolic rate, and this result deserves further exploration among other ectotherms. We conclude that, along with the previously reported lower cost of locomotion found in nocturnal lizards, they also partially offset the thermal handicap of activity at low body temperatures by having an elevated VO2 at lower temperatures.

Viviparity and Temperature-Dependent Sex Determination

Publisher: S. Karger AG

Date: 20-11-2010

DOI: 10.1159/000260373

Abstract: Although temperature-dependent sex determination (TSD) has been a ‘hot topic’ for well over 30 years, the discovery of TSD in viviparous taxa is recent. Viviparity and TSD was regarded unlikely on theoretical grounds as viviparity allows for high stable developmental temperatures through maternal basking. However, pregnant squamates of many species choose different body temperatures from non-pregnant females and males, and we now know that differential temperature selection by viviparous species with TSD allows for the production of sons or daughters. Three species of squamate reptiles (all are skinks) are now know to exhibit TSD. The physiological mechanism by which viviparous reptiles control the sex of their offspring is not understood, but exposure to different operational sex ratios in the adult population is a factor in some species. The functional role of sex steroid hormones in egg yolk and how the hormones are manipulated in utero is still an area requiring detailed investigation. Fast maturing squamate reptiles provide an excellent, but as yet underutilized, model system for studying the adaptive significance of TSD, and the occurrence of TSD in viviparous species requires substantially more work on a phylogenetically erse range of species.

Critically evaluating best management practices for preventing freshwater turtle extinctions

Publisher: Wiley

Date: 11-11-2017

DOI: 10.1111/COBI.12930

Abstract: Ex situ conservation tools, such as captive breeding for reintroduction, are considered a last resort to recover threatened or endangered species, but they may also help reduce anthropogenic threats where it is difficult or impossible to address them directly. Headstarting, or captive rearing of eggs or neonate animals for subsequent release into the wild, is controversial because it treats only a symptom of a larger conservation problem however, it may provide a mechanism to address multiple threats, particularly near population centers. We conducted a population viability analysis of Australia's most widespread freshwater turtle, Chelodina longicollis, to determine the effect of adult roadkill (death by collision with motor vehicles), which is increasing, and reduced recruitment through nest predation from introduced European red foxes (Vulpes vulpes). We also modeled management scenarios to test the effectiveness of headstarting, fox management, and measures to reduce mortality on roads. Only scenarios with headstarting from source populations eliminated all risks of extinction and allowed population growth. Small increases in adult mortality (2%) had the greatest effect on population growth and extinction risk. Where threats simultaneously affected other life-history stages (e.g., recruitment), eliminating harvest pressures on adult females alone did not eliminate the risk of population extinction. In our models, one source population could supply enough hatchlings annually to supplement 25 other similar-sized populations such that extinction was avoided. Based on our results, we believe headstarting should be a primary tool for managing freshwater turtles for which threats affect multiple life-history stages. We advocate the creation of source populations for managing freshwater turtles that are greatly threatened at multiple life-history stages, such as depredation of eggs by invasive species and adult mortality via roadkill.

Candidate genes involved in the evolution of viviparity: a RAD sequencing experiment in the lizard Zootoca vivipara (Squamata: Lacertidae)

Publisher: Oxford University Press (OUP)

Date: 19-10-2017

DOI: 10.1093/ZOOLINNEAN/ZLX069

Energy and nutrient utilisation by embryonic reptiles

Publisher: Elsevier BV

Date: 11-2002

DOI: 10.1016/S1095-6433(02)00188-5

Abstract: Most reptiles are oviparous, with the developing embryos relying on the contents of the yolk to sustain development until hatching (lecithotrophy). The yolk is composed primarily of lipid and protein, which act as an energy source and the essential components to build embryonic tissue. Nevertheless, yolk and the resulting embryos contain many other nutrients, including inorganic ions, vitamins, carotenoids, water and hormones. Apart from water and oxygen, which may be taken up by eggs, and some inorganic ions that can come from the eggshell or even from outside the egg, everything required by the embryo must be in the egg when it is laid. Approximately 20% of squamate reptiles are viviparous, exhibiting a variety of placental complexities. Species with complex placentae have reduced yolk volumes, with the mother augmenting embryonic nutrition by provision across the placenta (placentotrophy). Despite assumed advantages of placentotrophy, only 5 out of approximately 100 lineages of viviparous squamates exhibit substantial placentotrophy. This paper reviews available and recent information on the yolk contents of a variety of squamate reptiles to ask the question, how are nutrients transported from the yolk to the embryo or across the placenta? Although, current available data suggest that, in broad terms, yolk is taken up by embryos without discrimination of the nutrients, there are some apparent exceptions, including the very long chain polyunsaturated fatty acids. In addition, fundamental differences in the patterns of energy utilisation in lizards and snakes suggest fundamental differences in lipid profiles in these taxa, which appear to reflect the differences between placentotrophic and lecithotrophic viviparous lizards.

Placental ontogeny in Tasmanian snow skinks (genusNiveoscincus) (Lacertilia: Scincidae)

Publisher: Wiley

Date: 04-2009

DOI: 10.1002/JMOR.10704

Abstract: Lizards of the viviparous genus Niveoscincus contributed importantly to a classic model for the evolution of placentation of squamate reptiles. This model predicts that: (1) placental function is correlated with placental structural complexity and (2) the type of chorioallantoic placenta attributed to three species of Niveoscincus (N. metallicus, N. ocellatus, N. pretiosus) is intermediate in complexity to a highly placentotrophic type of placenta. Recent studies of two of these species (N. metallicus, N. ocellatus) revealed additional variation in placental structure, as well as variation in the level of placentotrophy N. metallicus is predominantly lecithotrophic, while N. ocellatus is highly placentotrophic. We used light microscopy to study placental ontogeny in two biennially reproducing species of Niveoscincus (N. greeni, N. microlepidotus) and placental morphology in late stage embryos of N. pretiosus. These data, in combination with prior studies, provide descriptions of placental structure for six of the eight species assigned to this lineage. The genus Niveoscincus has greater variation in placental structure than any other squamate lineage. We recognize four distinct groupings among these six species based on placental structure. The most highly placentotrophic species, N. ocellatus, has a complex placental morphology, yet shares these structures with a predominantly lecithotrophic species, N. microlepidotus. Thus, among species of Niveoscincus, placental structural complexity is not an infallible predictor of overall placental function.

Energetics of emergence in the cicadas, Cyclochila australasiae and Abricta curvicosta (Homoptera: Cicadidae)

Publisher: Elsevier BV

Date: 09-2006

DOI: 10.1016/J.JINSPHYS.2006.05.006

Abstract: The final moult in cicadas marks a major transition in lifestyle and is a behaviour that makes the cicada vulnerable to predation. Consequently, emergence times are short and, we predict, therefore the rate of energy consumption would be high. Hence, we measured the energetic cost of emergence in Cyclochila australasiae (green grocer) and Abricta curvicosta (floury baker) cicadas during the final moult from nymph to adult cicada. Maximum energy expended whilst emerging was compared between the sexes and species. Even though C. australasiae take longer to emerge than A. curvicosta, the mass-specific cost of emergence is not different between the two species (C. australasiae: 11.34+/-2.55 J g(-1) A. curvicosta: 12.91+/-1.90 J g(-1)). The mass-specific metabolic rates of fully emerged adults of both species are approximately twice those of the nymphs and the maximum metabolic rate during emergence is about 1.5 times higher than the resting metabolic rate of emerged adults. Emergence times, as indicated by rates of oxygen consumption, are longer than expected and probably reflect limitations in the oxygen capacity of the cicadas during moulting.

Tyrosine phosphorylated proteins in the reproductive tract of the viviparous lizard Eulamprus tympanum and the oviparous lizard Lampropholis guichenoti

Publisher: Elsevier BV

Date: 07-2006

DOI: 10.1016/J.CBPB.2006.04.005

Abstract: Plastic changes occur in the morphology of the uterus at various stages of the reproductive cycle in both oviparous and viviparous lizards and these may be influenced by estrogen. Estrogen driven phosphorylation of effector proteins on tyrosine residues plays a major role in the plastic modulation of uterine anatomy and physiology in vertebrates. We used electrophoresis and Western blotting to characterize the phosphotyrosine protein profiles at various stages of the reproductive pathway in an oviparous lizard L ropholis guichenoti and a viviparous lizard Eul rus tympanum. L. guichenoti displayed major bands in the 200-35 kDa range and a triplet of bands of molecular masses 61 kDa, 52 kDa and 48 kDa in 50% of specimens and a 38 kDa band in all specimens. In contrast, E. tympanum s les all displayed a single major band at 40 kDa, which was significantly elevated at the early pregnancy stage. Somewhat paradoxically, the viviparous species, which has the more complex uterine epithelial changes during pregnancy, has the fewest phosphotyrosine bands, so how tyrosine phosphorylation is affected during the evolution of viviparity is not clear.

Evaluating cognition and thermal physiology as components of the pace-of-life syndrome

Publisher: Springer Science and Business Media LLC

Date: 20-08-2018

DOI: 10.1007/S10682-018-9948-1

Uterine molecular changes for non‐invasive embryonic attachment in the marsupials Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae)

Publisher: Wiley

Date: 07-08-2017

DOI: 10.1002/MRD.22861

Abstract: Pregnancy in mammals requires remodeling of the uterus to become receptive to the implanting embryo. Remarkably similar morphological changes to the uterine epithelium occur in both eutherian and marsupial mammals, irrespective of placental type. Nevertheless, molecular differences in uterine remodeling indicate that the marsupial uterus employs maternal defences, including molecular reinforcement of the uterine epithelium, to regulate embryonic invasion. Non-invasive (epitheliochorial) embryonic attachment in marsupials likely evolved secondarily from invasive attachment, so uterine defences in these species may prevent embryonic invasion. We tested this hypothesis by identifying localization patterns of Talin, a key basal anchoring molecule, in the uterine epithelium during pregnancy in the tammar wallaby (Macropus eugenii Macropodidae) and the brush tail possum (Trichosurus vulpecula Phalangeridae). Embryonic attachment is non-invasive in both species, yet Talin undergoes a clear distributional change during pregnancy in M. eugenii, including recruitment to the base of the uterine epithelium just before attachment, that closely resembles that of invasive implantation in the marsupial species Sminthopsis crassicaudata. Basal localization occurs throughout pregnancy in T. vulpecula, although, as for M. eugenii, this pattern is most specific prior to attachment. Such molecular reinforcement of the uterine epithelium for non-invasive embryonic attachment in marsupials supports the hypothesis that less-invasive and non-invasive embryonic attachment in marsupials may have evolved via accrual of maternal defences. Recruitment of basal molecules, including Talin, to the uterine epithelium may have played a key role in this transition.

Facultative sex allocation in the viviparous lizard Eulamprus tympanum, a species with temperature-dependent sex determination

Publisher: CSIRO Publishing

Date: 2003

DOI: 10.1071/ZO03016

Abstract: Females of the Australian scincid lizard Eul rus tympanum can manipulate the sex of their offspring in response to gender imbalances in the population using temperature-dependent sex determination. Here we show that when adult males are scarce females produced male-biased litters and when adult males were common females produced female-biased litters. The cues used by a female to assess the adult population are not known but presumably depend upon her experience throughout the breeding season. Maternal manipulation of the sex ratio of the offspring in E. tympanum illustrates a selective advantage of temperature-dependent sex determination in a viviparous species.

Functional Plasticity of the Developing Cardiovascular System: Examples from Different Vertebrates

Publisher: University of Chicago Press

Date: 09-2010

DOI: 10.1086/656004

Abstract: Technical advances that have made it possible to perform physiological measurements on very small organisms, including those in embryonic and larval stages, have resulted in the formation of the discipline of developmental physiology. The transparency and size of developing organisms in some areas permit insights into physiological processes that cannot be obtained with opaque, adult organisms. On the other hand, it is widely accepted that without eggs, there are no chickens, so physiological adaptations during early life are just as important to species survival as those manifested by adults. Physiological adaptations of early developmental stages, however, are not always the same as patterns known in adults they often follow their own rules. The adaptability of early developmental stages demonstrates that development is not stereotyped and a phenotype is not just the result of genetic information and the expression of a certain series of genes. Environmental factors influence phenotype production, and this in turn results in flexibility and plasticity in physiological processes. This article comprises exemplary studies presented at the Fourth International Conference in Africa for Comparative Physiology and Biochemistry (Maasai Mara, Kenya, 2008). It includes a brief introduction into technical advances, discusses the developing cardiovascular system of various vertebrates, and demonstrates the flexibility and plasticity of early developmental stages. Fluid forces, oxygen availability, ionic homeostasis, and the chemical environment (including, e.g., hormone concentrations or cholesterol levels) all contribute to the shaping and performance of the cardiovascular system.

Yolk sac development in lizards (Lacertilia: Scincidae): New perspectives on the egg of amniotes

Publisher: Wiley

Date: 06-02-2017

DOI: 10.1002/JMOR.20656

Abstract: Embryos of oviparous reptiles develop on the surface of a large mass of yolk, which they metabolize to become relatively large hatchlings. Access to the yolk is provided by tissues growing outward from the embryo to cover the surface of the yolk. A key feature of yolk sac development is a dedicated blood vascular system to communicate with the embryo. The best known model for yolk sac development and function of oviparous amniotes is based on numerous studies of birds, primarily domestic chickens. In this model, the vascular yolk sac forms the perimeter of the large yolk mass and is lined by a specialized epithelium, which takes up, processes and transports yolk nutrients to the yolk sac blood vessels. Studies of lizard yolk sac development, dating to more than 100 years ago, report characteristics inconsistent with this model. We compared development of the yolk sac from oviposition to near hatching in embryonic series of three species of oviparous scincid lizards to consider congruence with the pattern described for birds. Our findings reinforce results of prior studies indicating that squamate reptiles mobilize and metabolize the large yolk reserves in their eggs through a process unknown in other amniotes. Development of the yolk sac of lizards differs from birds in four primary characteristics, migration of mesoderm, proliferation of endoderm, vascular development and cellular ersity within the yolk sac cavity. Notably, all of the yolk is incorporated into cells relatively early in development and endodermal cells within the yolk sac cavity align along blood vessels which course throughout the yolk sac cavity. The pattern of uptake of yolk by endodermal cells indicates that the mechanism of yolk metabolism differs between lizards and birds and that the evolution of a fundamental characteristic of embryonic nutrition erged in these two lineages. Attributes of the yolk sac of squamates reveal the existence of phylogenetic ersity among amniote lineages and raise new questions concerning the evolution of the amniotic egg. J. Morphol. 278:574-591, 2017. © 2017 Wiley Periodicals, Inc.

Does Low Gas Permeability of Rigid‐Shelled Gekkotan Eggs Affect Embryonic Development?

Publisher: Wiley

Date: 12-03-2013

DOI: 10.1002/JEZ.1790

Abstract: Parchment-shelled eggs are characteristic of most squamates, including the basal clades of gekkotan lizards. The majority of gekkotan lizards, however, produce rigid-shelled eggs that are highly impermeable to gas exchange eggs are laid in dry sites and experience a net loss of water during incubation. We tested the hypothesis that the 1,000-fold lower rate of oxygen diffusion through the shells of rigid- compared to parchment-shelled eggs imposes a physiological cost on development. To do this, we contrasted species with rigid and with parchment shells with regards to (1) rates of embryonic metabolism and (2) rates and patterns of development of the yolk sac and chorioallantois, the vascularized extra-embryonic membranes that transport oxygen to embryonic tissues. Metabolic rates of embryos from the rigid-shelled eggs of Gehyra variegata did not differ from those of the parchment-shelled eggs of Oedura lesueurii. Moreover, maximum metabolic rates of gekkotans with rigid shells did not differ from those of gekkotan or scincid lizards with parchment shells. In contrast, the yolk sac covered more of the surface area of the egg at oviposition, and the chorioallantois reached its full extent earlier for the species with rigid shelled eggs (Chondrodactylus turneri, G. variegata) than for the species with parchment-shelled eggs (Eublepharis macularius, O. lesueurii). Differences in the temporal patterns of yolk sac and chorioallantois development would thus serve to compensate for low rates of oxygen diffusion through rigid shells of gekkotans.

Morphology and development of the placentae in Eulamprus quoyii group skinks (Squamata: Scincidae)

Publisher: Wiley

Date: 16-03-2012

DOI: 10.1111/J.1469-7580.2012.01492.X

Conditioning reduces metabolic rate and time to steady-state in the lizard Naultinus manukanus (Reptilia: Gekkonidae)

Publisher: Elsevier BV

Date: 10-2004

DOI: 10.1016/J.CBPB.2004.09.009

Abstract: The rate of oxygen consumption (VO2) is commonly used as a measure of whole organism metabolic rate, but requires the animal to be motionless and at rest. Few studies have measured whether animals that appear motionless are truly at rest, or whether being in a novel environment elevates metabolic rate. We investigated whether conditioning of the gecko Naultinus manukanus to experimental procedures influenced the VO2 and probability of achieving a constant rate of oxygen consumption. Metabolic rate was measured at 24 degrees C in 22 in iduals until a steady-state was achieved, or for 80 min if no steady-state was reached, once a day on 5 consecutive days (five trials). Geckos in the first trial, when compared with subsequent trials, had a significantly higher mass-adjusted VO2 (0.89+/-0.06 vs. 0.67+/-0.05 ml O2 h(-1), respectively), and time to reach a steady-state VO2 (66+/-8 vs. 47+/-3 min, respectively), as well as a significantly lower probability of reaching a steady-state VO2 (24% vs. 74%, respectively). We conclude that there may be hidden inaccuracies in studies that do not condition animals and that at least one conditioning trial should be used to obtain a metabolic rate at rest for small lizards.

Road mortality of the eastern long-necked turtle (Chelodina longicollis) along the Murray River, Australia: an assessment using citizen science

Publisher: CSIRO Publishing

Date: 2018

DOI: 10.1071/ZO17065

Abstract: Turtles face a variety of threats (e.g. habitat destruction, introduced predators) that are pushing many species towards extinction. Vehicle collisions are one of the main causes of mortality of adult freshwater turtles. To conceptualise the level of threat that roads pose to Australians turtles, we analysed data gathered through the citizen science project TurtleSAT along the Murray River. We recorded 124 occurrences of turtle road mortality, which included all three local species (Chelodina expansa, Chelodina longicollis, and Emydura macquarii). Chelodina longicollis was the most commonly reported species killed on roads. We found that rain and time of year affect the likelihood of C. longicollis being killed on roads: increased turtle mortality is associated with rain events and is highest during the month of November, which coincides with their nesting season. Chelodina longicollis was most likely to be killed on the Hume Highway and roads around major urban centres therefore, we recommend that governing bodies focus management practices and increase awareness at these locations. The degree of road mortality that we detected in this study requires mitigation, as it may contribute to the decline of C. longicollis along the Murray River.

A review of the evolution of viviparity in lizards: structure, function and physiology of the placenta

Publisher: Springer Science and Business Media LLC

Date: 07-12-2005

DOI: 10.1007/S00360-005-0048-5

Abstract: The aim of this review is to collate data relevant to understanding the evolution of viviparity in general, and complex placentae in particular. The wide range of reproductive modes exhibited by lizards provides a solid model system for investigating the evolution of viviparity. Within the lizards are oviparous species, viviparous species that have a very simple placenta and little nutrient uptake from the mother during pregnancy (lecithotrophic viviparity), through a range of species that have intermediate placental complexities and placental nutrient provision, to species that lay microlecithal eggs and most nutrients are provided across the placenta during development (obligate placentotrophy). In its commonest form, lecithotrophic viviparity, some uptake of water, inorganic ions and oxygen occurs from the mother to the embryo during pregnancy. In contrast, the evolution of complex placentae is rare, but has evolved at least five times. Where there is still predominantly a reliance on egg yolk, the omphaloplacenta seems to be paramount in the provision of nutrition to the embryo via histotrophy, whereas the chorioallantoic placenta is more likely involved in gas exchange. Reliance on provision of substantial organic nutrient is correlated with the regional specialisation of the chorioallantoic placenta to form a placentome for nutrient uptake, particularly lipids, and the further development of the gas exchange capabilities of the other parts of the chorioallantois.

Evaluating the performance of anchored hybrid enrichment at the tips of the tree of life: A phylogenetic analysis of Australian Eugongylus group scincid lizards

Publisher: Springer Science and Business Media LLC

Date: 11-04-2015

DOI: 10.1186/S12862-015-0318-0

Placental ontogeny of the Tasmanian scincid lizard,Niveoscincus ocellatus (Reptilia: Squamata)

Publisher: Wiley

Date: 2004

DOI: 10.1002/JMOR.10179

Abstract: A prominent scenario for the evolution of reptilian placentation infers that placentotrophy arose by gradual modification of a simple vascular chorioallantoic placenta to a complex structure with a specialized region for nutrient transfer. The structure of the chorioallantoic placenta of Niveoscincus ocellatus, apparently described originally from a single embryonic stage, was interpreted as a transitional evolutionary type that provided support for the model. Recently, N. ocellatus has been found to be as placentotrophic as species with complex chorioallantoic placentae containing a specialized region called a placentome. We studied placental development in N. ocellatus and confirmed that the chorioallantoic placenta lacks specializations found in species with a placentome. We also found that this species has a specialized omphaloplacenta. The chorioallantoic placenta is confined to the region adjacent to the embryo by a membrane, similar to that found in some other viviparous skinks, that ides the egg into embryonic and abembryonic hemispheres. We term this structure the "inter-omphalopleuric" membrane. The position of this membrane in N. ocellatus is closer to the embryonic pole of the egg than to the abembryonic pole and thus the surface area of the omphaloplacenta is greater than that of the chorioallantoic placenta. In addition, the omphaloplacenta is regionally ersified and more complex histologically than the chorioallantoic placenta. An impressive and unusual feature of the omphaloplacenta of N. ocellatus is the development of extensive overlapping folds in the embryonic component of mid-gestation embryos. The histological complexity and extensive folding of the omphaloplacenta make this a likely site of placental transfer of nutrients in this species.

Epithelial cadherin disassociates from the lateral plasma membrane of uterine epithelial cells throughout pregnancy in a marsupial

Publisher: Wiley

Date: 03-07-2017

DOI: 10.1111/JOA.12648

Evolution of viviparity and uterine angiogenesis: vascular endothelial growth factor (VEGF) in oviparous and viviparous skinks

Publisher: Wiley

Date: 2009

DOI: 10.1002/JEZ.B.21317

Abstract: During pregnancy, uterine vasculature of live-bearing lizards proliferates to support embryonic growth and development. Vascular endothelial growth factor (VEGF) is the most potent of a suite of growth factors responsible for uterine vascularization in mammals. We have sequenced VEGF mRNA transcripts expressed in the uterus of oviparous and viviparous Australian skinks, and compared uterine VEGF expression in nonreproductive and late-reproductive Saiphos equalis, a fossorial viviparous skink. VEGF sequences differed between phylogenetic groups of skinks, rather than oviparous and viviparous skinks. Two transcripts were identified in the uterus of each species that had the same splice sites as human VEGF(165) and VEGF(189). A third transcript, found only in uterine and testis tissue from S. equalis, had the same splice sites as human VEGF(111). This is the first natural expression of VEGF(111), previously found only in human cultured cells subjected to environmental stress. All the three VEGF transcripts identified showed higher expression in uterus from late-reproductive S. equalis than nonreproductive females. The different angiogenic properties of VEGF transcripts provide a mechanism that may produce the variety of placental complexities observed in viviparous skinks. The presence of VEGF(111) in S. equalis may be an opportunity to investigate the function of this unique transcript in a whole animal system.

COUNTERINTUITIVE DENSITY-DEPENDENT GROWTH IN A LONG-LIVED VERTEBRATE AFTER REMOVAL OF NEST PREDATORS

Publisher: Wiley

Date: 12-2006

DOI: 10.1890/0012-9658(2006)87[3109:CDGIAL]2.0.CO;2

Abstract: Examining the phenotypic and genetic underpinnings of life-history variation in long-lived organisms is central to the study of life-history evolution. Juvenile growth and survival are often density dependent in reptiles, and theory predicts the evolution of slow growth in response to low resources (resource-limiting hypothesis), such as under densely populated conditions. However, rapid growth is predicted when exceeding some critical body size reduces the risk of mortality (mortality hypothesis). Here we present results of paired, large-scale, five-year field experiments to identify causes of variation in in idual growth and survival rates of an Australian turtle (Emydura macquarii) prior to maturity. To distinguish between these competing hypotheses, we reduced nest predators in two populations and retained a control population to create variation in juvenile density by altering recruitment levels. We also conducted a complementary split-clutch field-transplant experiment to explore the impact of incubation temperature (25 degrees or 30 degrees C), nest predator level (low or high), and clutch size on juvenile growth and survival. Juveniles in high-recruitment (predator removal) populations were not resource limited, growing more rapidly than young turtles in the control populations. Our experiments also revealed a remarkably long-term impact of the thermal conditions experienced during embryonic development on growth of turtles prior to maturity. Moreover, this thermal effect was manifested in turtles approaching maturity, rather than in turtles closer to hatching, and was dependent on population density in the post-hatching rearing environment. This apparent phenotypic plasticity in growth complements our observation of a strong, positive genetic correlation between in idual body size in the experimental and control populations over the first five years of life (rG - +0.77). Thus, these Australian pleurodiran turtles have the impressive capacity to acclimate plastically to major demographic perturbations and enjoy the longer-term potential to evolve adaptively to maintain viability.

Desmosomes in the Uterine Epithelium of Noninvasive Skink Placentae

Publisher: Wiley

Date: 18-02-2010

DOI: 10.1002/AR.21093

Abstract: Australian species of viviparous skinks have noninvasive epitheliochorial placentation where there is no breeching or interruption of the uterine epithelial cell barrier. This is contrary to some African and South American species of skinks which exhibit invading chorionic cells and a localized endotheliochorial placenta. The desmosomes, which maintain the adhesive properties of the junctional complex between uterine epithelial cells, were found to decrease as gestation progressed in the uterus of two highly placentotrophic Australian skinks, but no changes in desmosomal numbers were present in the uterus of two Australian oviparous skinks or viviparous skinks with a simple placenta. In mammals, desmosomes decrease in the uterine epithelium of species with invasive hemochorial placentation, where less chemical and mechanical adhesion between cells assists the invading trophoblast at the time of implantation. However, Australian viviparous skinks do not have an invasive trophoblast yet, similarities in decreasing lateral cellular adhesion exist in the uterus of both invasive and noninvasive placental types. This similarity in cellular mechanisms suggests a conservation of plasma membrane changes across placentation irrespective of reptilian or mammalian origin.

A matter of time: Temporal variation in the introduction history and population genetic structuring of an invasive lizard

Publisher: Oxford University Press (OUP)

Date: 06-2015

DOI: 10.1093/CZOOLO/61.3.456

Abstract: Invasive species are considered one of the greatest threats to native ecosystems, second only to habitat loss and fragmentation. Despite this, the temporal dynamics of invasions are poorly understood, with most studies focusing on a single time point, providing us with only a snapshot of the biology and genetics of the invader. We investigated the invasion of Lord Howe Island by the delicate skink L ropholis delicata and assessed the introduction history and genetic structure of this species over a 5-year period. Using genetic data taken from 2007, and again in 2011/12, we examined changes in the population genetic structure (whether new haplotypes had been introduced to the island, and shifts in haplotype frequencies) of the species on the island between these two time points. No new haplotypes were introduced to the island between 2007 and 2011/12 however, significant shifts in haplotype frequencies across the island were detected. We conclude that the delicate skink is expanding its range into the southern regions of the island and that the haplotype frequencies on Lord Howe Island are still in a state of highly dynamic flux. Our study highlights the importance of considering invasions as dynamic and studying them in such a way that enable us to better manage their impacts.

No implantation in an extra-uterine pregnancy of a placentotrophic reptile

Publisher: Elsevier BV

Date: 06-2013

DOI: 10.1016/J.PLACENTA.2013.03.002

Abstract: Placentation is a common feature of live-bearing reptiles and mammals. Placentae are variable between species and can be classified by the extent that embryonic tissue breaches (invades) the uterus. Non-invasive placentation in eutherians is maternally imposed as extra-uterine embryos of species with epitheliochorial placentation will readily invade non-uterine tissues. This study documents the first observation of an extra-uterine pregnancy in a reptile Pseudemoia entrecasteauxii, which in-utero exhibits non-invasive epitheliochorial placentation. The extra-uterine embryo did not invade maternal tissue suggesting fundamental differences between the nature and evolution of placentation in P. entrecasteauxii and eutherian mammals.

Intragonadal incubation of progeny in three viviparous asterinid sea stars that differ in offspring provisioning, lecithotrophy vs matrotrophy

Publisher: Springer Science and Business Media LLC

Date: 22-05-2019

DOI: 10.1007/S00227-019-3507-3

Patterns of niche filling and expansion across the invaded ranges of an Australian lizard

Publisher: Wiley

Date: 21-05-2016

DOI: 10.1111/ECOG.01576

VEGF111: New insights in tissue invasion

Publisher: Frontiers Media SA

Date: 22-01-2015

DOI: 10.3389/FPHYS.2015.00002

Viviparous lizard, Eulamprus tympanum, shows changes in the uterine surface epithelium during early pregnancy that are similar to the plasma membrane transformation of mammals

Publisher: Wiley

Date: 23-10-2003

DOI: 10.1002/JMOR.10163

Abstract: The "plasma membrane transformation" describes a series of ultrastructural, biochemical, and morphological changes that occur in the uterus of many mammals at the time of blastocyst attachment. These changes, regardless of placental type or length of gestation, include alterations to microvillar length and density and the presence or absence of pinopods or uterodomes. Scanning electron microscopy (SEM) was used to 1) document the topographical ultrastructure of the uterus of Eul rus tympanum, an eastern Australian viviparous skink with a simple chorioallantoic placenta, for the first time and 2) determine whether changes identified as "plasma membrane transformation" in mammals occur in E. tympanum. Tissues collected over three seasons from nonreproductive subadult females, preovulatory, postovulatory, and early to mid-gestational females were examined. At low magnification the uterine epithelium of subadults displays a distinctive pattern of tissue folding that includes rectangular areas of tissue delineated by deep lateral and transverse folds. At higher magnification, the uterine epithelium surface is composed of two dominant cell types, i.e., those covered by microvilli and ciliated cells. The folding pattern observed in subadults is less evident in vitellogenic females and the cell surfaces appear highly secretory, with bulging cell apices. Tissue from postovulatory lizards has no distinctive folding pattern and cell surfaces are frequently smooth and lack microvilli. Uterine egg chambers lack ciliated cells at the embryonic pole, but display abundant secretory droplets. Thus, the uterus of E. tympanum undergoes a plasma membrane transformation. The scope of this transformation is not fully understood but may be related to the complexity of placental structure and the development of the embryo/fetus at parturition.

Egg mass determines hatchling size, and incubation temperature influences post‐hatching growth, of tuatara Sphenodon punctatus

Publisher: Wiley

Date: 05-2004

DOI: 10.1017/S095283690400490X

Induction of oviposition produces smaller eggs in tuatara(Sphenodon punctatus)

Publisher: Informa UK Limited

Date: 2004

DOI: 10.1080/03014223.2004.9518381

Effects of Warm Temperatures on Metabolic Rate and Evaporative Water Loss in Tuatara, a Cool-Climate Rhynchocephalian Survivor

Publisher: University of Chicago Press

Date: 07-2018

DOI: 10.1086/698495

Abstract: The thermal sensitivity of physiological rates is a key characteristic of organisms. For tuatara (Sphenodon punctatus), the last surviving member of the reptilian order Rhynchocephalia and an unusually cold-tolerant reptile, we aimed to clarify responses in indices of metabolic rate (oxygen consumption [[Formula: see text]] and carbon dioxide production [[Formula: see text]]) as well as rates of total evaporative water loss (TEWL) to temperatures at the warmer end of the known tolerated range currently, patterns for metabolic rate are unclear above 25°C, and TEWL has not been measured above 25°C. We first established that metabolic rate was lowest during the photophase and then measured [Formula: see text], [Formula: see text], and TEWL at six temperatures (12°, 20°, 24°, 27°, 29°, and 30°C) during this phase. Consistent with our predictions, we found that mass-adjusted [Formula: see text], [Formula: see text], and TEWL increased at least 3.5-fold between 12° and 30°C (at 30°C, rates were 2.509 mL g

Reptile Pregnancy Is Underpinned by Complex Changes in Uterine Gene Expression: A Comparative Analysis of the Uterine Transcriptome in Viviparous and Oviparous Lizards

Publisher: Oxford University Press (OUP)

Date: 15-09-2016

DOI: 10.1093/GBE/EVW229

Population parameters and life-table analysis of two coexisting freshwater turtles: are the Bellinger River turtle populations threatened?

Publisher: CSIRO Publishing

Date: 2005

DOI: 10.1071/WR04083

Abstract: Two species of freshwater turtle coexist in the Bellinger River: Elseya georgesi is common but limited to the Bellinger River, whereas Emydura macquarii is widespread but rare in the Bellinger River. The Bellinger River population of E. macquarii has been proposed as a distinct subspecies, so it may be endangered. Survivorship, fecundity, growth, size and age were determined for El. georgesi and the finite rate of increase (λ) was estimated by a life-table analysis using mark–recapture data from surveys between 1988 and 2004. These parameters were compared with those of well studied populations of E. macquarii to assess whether modelling the demographic parameters of El. georgesi could serve as a surrogate for estimating the influences of these demographic parameters on λ in the Bellinger River population of E. macquarii. We estimated that ~4500 El. georgesi inhabit the study area and, despite a size distribution strongly biased towards large in iduals, the population is increasing (λ = 1.15) in the best-case scenario, or slightly decreasing (λ = 0.96) in the worst-case scenario. Comparing El. georgesi with E. macquarii from the Bellinger River and elsewhere suggests that E. macquarii grows faster, attains greater maximum size, has a greater clutch size and a higher fecundity than El. georgesi. Hence, El. georgesi does not serve as a good surrogate to determine demographic influences on λ in E. macquarii.

Dynamic changes to claudins in the uterine epithelial cells of the marsupial Sminthopsis crassicaudata (Dasyuridae) during pregnancy

Publisher: Wiley

Date: 04-04-2019

DOI: 10.1002/MRD.23140

Abstract: The fluid that surrounds the embryo in the uterus contains important nourishing factors and secretions. To maintain the distinct microenvironment in the uterine lumen, the tight junctions between uterine epithelial cells are remodeled to decrease paracellular movement of molecules and solutes. Modifications to tight junctions between uterine epithelial cells is a common feature of pregnancy in eutherian mammals, regardless of placental type. Here we used immunofluorescence microscopy and western blot analysis to describe distributional changes to tight junctional proteins, claudin-1, -3, -4, and -5, in the uterine epithelial cells of a marsupial species, Sminthopsis crassicaudata. Immunofluorescence microscopy revealed claudin-1, -3, and -5 in the tight junctions of the uterine epithelium of S. crassicaudata during pregnancy. These specific claudins are associated with restricting passive movement of fluid between epithelial cells in eutherians. Hence, their function during pregnancy in S. crassicaudata may be to maintain the uterine luminal content surrounding developing embryos. Claudin-4 disappears from all uterine regions of S. crassicaudata at the time of implantation, in contrast with the distribution of this claudin in some eutherian mammals. We conclude that like eutherian mammals, distributional changes to claudins in the uterine epithelial cells of S. crassicaudata are necessary to support pregnancy. However, the combination of in idual claudin isoforms in the tight junctions of the uterine epithelium of S. crassicaudata differs from that of eutherian mammals. Our findings suggest that the precise permeability of the paracellular pathway of the uterine epithelium is species-specific.

Oxygen levels in mound nests ofCrocodylus porosusandAlligator mississippiensisare high, and gas exchange occurs primarily by diffusion, not convection

Publisher: Royal Zoological Society of New South Wales

Date: 2010

DOI: 10.7882/AZ.2010.012

Behavioral Responses to Immune-System Activation in an Anuran (the Cane Toad, Bufo marinus): Field and Laboratory Studies

Publisher: University of Chicago Press

Date: 2011

DOI: 10.1086/657609

Abstract: The challenges posed by parasites and pathogens evoke behavioral as well as physiological responses. Such behavioral responses are poorly understood for most ectothermic species, including anuran hibians. We quantified effects of simulated infection (via injection of bacterial lipopolysaccharide [LPS]) on feeding, activity, and thermoregulation of cane toads Bufo marinus within their invasive range in tropical Australia. LPS injection reduced feeding rates in laboratory trials. For toads in outdoor enclosures, LPS injection reduced activity and shifted body temperature profiles. Although previous research has attributed such thermal shifts to behavioral fever (elevated body temperatures may help fight infection), our laboratory studies suggest instead that LPS-injected toads stopped moving. In a thermal gradient, LPS-injected toads thus stayed close to whichever end of the gradient (hot or cold) they were first introduced the introduction site (rather than behavioral thermoregulation) thus determined body temperature regimes. Shifts in thermal profiles of LPS-injected toads in outdoor enclosures also were a secondary consequence of inactivity. Thus, the primary behavioral effects of an immune response in cane toads are reduced rates of activity and feeding. Thermoregulatory modifications also occur but only as a secondary consequence of inactivity.

Placental lipoprotein lipase (LPL) gene expression in a placentotrophic lizard,Pseudemoia entrecasteauxii

Publisher: Wiley

Date: 08-2013

DOI: 10.1002/JEZ.B.22526

Abstract: Viviparity (live birth) relies on a functional placenta, which is formed by cooperating maternal and embryonic tissues. In some viviparous lineages, mothers use this placenta to transport nutrients to feed developing embryos through pregnancy (placentotrophy). The Australian lizard, Pseudemoia entrecasteauxii, provides approximately 60% of the lipid for embryonic growth and metabolism to embryos across the placenta. Lipoprotein lipase (LPL) is an important enzyme in lipid transport in vertebrates. We examined patterns of LPL gene expression to identify its role in the uterus of pregnant P. entrecasteauxii. We used reverse transcription quantitative real time PCR to measure the expression of the LPL gene in the uterine tissue throughout reproduction and compared uterine LPL expression in chorioallantoic and yolk-sac placentae. Expression of the LPL gene is significantly higher in the uterus of late pregnant compared to non-pregnant and early pregnant P. entrecasteauxii, indicating a greater capacity for lipid transport towards the end of pregnancy. The period of high LPL gene expression correlates with the time that developing embryos are undergoing the greatest growth and have the highest metabolic rate. LPL gene expression is significantly higher in the uterine tissue of the yolk-sac placenta than the chorioallantoic placenta, providing the first molecular evidence that the yolk-sac placenta is the major site of lipid transport in pregnant P. entrecasteauxii.

Why cross the web: decoration spectral properties and prey capture in an orb spider (Argiope keyserlingi) web

Publisher: Oxford University Press (OUP)

Date: 30-05-2008

DOI: 10.1111/J.1095-8312.2008.00999.X

Transition from ectothermy to endothermy: the development of metabolic capacity in a bird (Gallus gallus)

Publisher: The Royal Society

Date: 07-12-2005

DOI: 10.1098/RSPB.2005.3333

Abstract: The evolution of endothermy is one of the most significant events in vertebrate evolution. Adult mammals and birds are delineated from their early ontogenetic stages, as well as from other vertebrates, by high resting metabolic rates and consequent internal heat production. We used the embryonic development of a bird ( Gallus gallus ) as a model to investigate the metabolic transition between ectothermy and endothermy. Increases in aerobic capacity occur at two functional levels that are regulated independently from each other: (i) upregulation of gene expression and (ii) significant increases in the catalytic activity of the main oxidative control enzymes. Anaerobic capacity, measured as lactate dehydrogenase activity, is extremely high during early development, but diminishes at the same time as aerobic capacity increases. Changes in lactate dehydrogenase activity are independent from its gene expression. The regulatory mechanisms that lead to endothermic metabolic capacity are similar to those of ectotherms in their response to environmental change. We suggest that the phylogenetic occurrence of endothermy is restricted by its limited selective advantages rather than by evolutionary innovation.

Uterine and eggshell modifications associated with the evolution of viviparity in South American water snakes (Helicops spp.)

Publisher: Wiley

Date: 14-04-2018

DOI: 10.1002/JEZ.B.22800

Uterine epithelial morphology and progesterone receptors in a mifepristone-treated viviparous lizard pseudemoia entrecasteauxii (Squamata: Scincidae) during gestation

Publisher: Wiley

Date: 03-2012

DOI: 10.1002/JEZ.B.22003

Abstract: Structural and functional changes to the uterus associated with maintenance of pregnancy are controlled primarily by steroid hormones such as progesterone. We tested the hypothesis that progesterone regulates uterine structural changes during pregnancy in the viviparous skink, Pseudemoia entrecasteauxii, by treating pregnant females with the progesterone receptor antagonist mifepristone at different stages of pregnancy. Expression and distribution of progesterone receptor was determined using Western blot and immunohistochemistry. During early pregnancy, mifepristone treatment resulted in altered uterine epithelial cell surface morphology and high embryo mortality, but did not affect females at mid and late stages of pregnancy. Females treated with mifepristone in early pregnancy exhibited abnormal uterine epithelial cell morphology such as lateral blebbing and presence of wide gaps between cells indicating loss of intercellular attachment. Chorioallantoic membranes of the embryo were not affected by mifepristone treatment. Two isoforms (55 kDa and 100 kDa) of progesterone receptor were identified using immunoblots and both isoforms were localized to the nucleus of uterine epithelial cells. The 55 kDa isoform was expressed throughout pregnancy, whereas the 100 kDa isoform was expressed during mid and especially late pregnancy. In P. entrecasteauxii, mifepristone may prevent successful embryo attachment in early pregnancy through its effects on uterine epithelial cells but may have little effect on pregnancy once the maternal-embryo structural relationship is established.

Do TSD, sex ratios, and nest characteristics influence the vulnerability of tuatara to global warming?

Publisher: Elsevier BV

Date: 12-2004

DOI: 10.1016/J.ICS.2004.08.093

The first pterosaur 3-D egg: Implications for Pterodaustro guinazui nesting strategies, an Albian filter feeder pterosaur from central Argentina

Publisher: Elsevier BV

Date: 11-2014

DOI: 10.1016/J.GSF.2014.05.002

Micro-CT scan reveals an unexpected high-volume and interconnected pore network in a Cretaceous Sanagasta dinosaur eggshell

Publisher: The Royal Society

Date: 03-2016

DOI: 10.1098/RSIF.2016.0008

Abstract: The Cretaceous Sanagasta neosauropod nesting site (La Rioja, Argentina) was the first confirmed instance of extinct dinosaurs using geothermal-generated heat to incubate their eggs. The nesting strategy and hydrothermal activities at this site led to the conclusion that the surprisingly 7 mm thick-shelled eggs were adapted to harsh hydrothermal microenvironments. We used micro-CT scans in this study to obtain the first three-dimensional microcharacterization of these eggshells. Micro-CT-based analyses provide a robust assessment of gas conductance in fossil dinosaur eggshells with complex pore canal systems, allowing calculation, for the first time, of the shell conductance through its thickness. This novel approach suggests that the shell conductance could have risen during incubation to seven times more than previously estimated as the eggshell erodes. In addition, micro-CT observations reveal that the constant widening and branching of pore canals form a complex funnel-like pore canal system. Furthermore, the high density of pore canals and the presence of a lateral canal network in the shell reduce the risks of pore obstruction during the extended incubation of these eggs in a relatively highly humid and muddy nesting environment.

Isolation and characterization of microsatellite loci from the invasive delicate skink (Lampropholis delicata), with cross-amplification in other Australian Eugongylus group species

Publisher: Springer Science and Business Media LLC

Date: 19-05-2009

DOI: 10.1007/S12686-009-9013-Z

Selective consumption by predators of different body regions of prey: is rate of energy intake important?

Publisher: Wiley

Date: 10-2004

DOI: 10.1017/S0952836904005692

Seahorse Brood Pouch Transcriptome Reveals Common Genes Associated with Vertebrate Pregnancy

Publisher: Oxford University Press (OUP)

Date: 09-2015

DOI: 10.1093/MOLBEV/MSV177

Abstract: Viviparity (live birth) has evolved more than 150 times in vertebrates, and represents an excellent model system for studying the evolution of complex traits. There are at least 23 independent origins of viviparity in fishes, with syngnathid fishes (seahorses and pipefish) unique in exhibiting male pregnancy. Male seahorses and pipefish have evolved specialized brooding pouches that provide protection, gas exchange, osmoregulation, and limited nutrient provisioning to developing embryos. Pouch structures differ widely across the Syngnathidae, offering an ideal opportunity to study the evolution of reproductive complexity. However, the physiological and genetic changes facilitating male pregnancy are largely unknown. We used transcriptome profiling to examine pouch gene expression at successive gestational stages in a syngnathid with the most complex brood pouch morphology, the seahorse Hippoc us abdominalis. Using a unique time-calibrated RNA-seq data set including brood pouch at key stages of embryonic development, we identified transcriptional changes associated with brood pouch remodeling, nutrient and waste transport, gas exchange, osmoregulation, and immunological protection of developing embryos at conception, development and parturition. Key seahorse transcripts share homology with genes of reproductive function in pregnant mammals, reptiles, and other live-bearing fish, suggesting a common toolkit of genes regulating pregnancy in ergent evolutionary lineages.

Experimental Analysis of the Impact of Foxes on Freshwater Turtle Populations

Publisher: Wiley

Date: 06-2005

DOI: 10.1111/J.1523-1739.2005.00487.X

Effects of Urbanization on Behavior, Performance, and Morphology of the Garden Skink, Lampropholis guichenoti

Publisher: Society for the Study of Amphibians and Reptiles

Date: 06-2006

DOI: 10.1670/38-05A.1

Partitioning of temporal activity among desert lizards in relation to prey availability and temperature

Publisher: Wiley

Date: 21-01-2010

DOI: 10.1111/J.1442-9993.2009.02010.X

Maternal provision and embryonic uptake of calcium in an oviparous and a placentotrophic viviparous Australian lizard (Lacertilia: Scincidae)

Publisher: Elsevier BV

Date: 06-2009

DOI: 10.1016/J.CBPA.2009.02.014

Abstract: Embryos of oviparous lizards have two sources of calcium for embryonic development: 1) calcium that accumulates in yolk during vitellogenesis, and 2) calcium carbonate deposited in the eggshell from oviductal secretions. Eggs of viviparous lizards lack a calcified eggshell and calcium secreted by the uterus is delivered to the embryo across a placenta. Whereas oviparous lizard embryos recover calcium from the eggshell during late developmental growth stages, viviparous embryos have a lengthy intimate association with the uterus and the potential for an extended interval of placental calcium transfer. We compared the pattern of calcium mobilization of embryos of the viviparous, placentotrophic scincid lizard, Pseudemoia pagenstecheri, to that of a closely related oviparous species, Saproscincus mustelinus, to determine if the timing of uterine calcium secretion was influenced by reproductive mode. Embryos of both species receive a substantial amount of calcium from either the eggshell or placenta (54% and 85% respectively). The ontogeny of calcium uptake by embryos of P. pagenstecheri reveals that the onset of embryonic acquisition of calcium occurs earlier relative to embryonic stage but the timing of peak uterine secretion of calcium is delayed, compared to S. mustelinus.

Temporal pattern of offspring release and degree of parental investment in two viviparous asterinid sea stars with an overview of matrotrophy and offspring size variation in echinoderms that care for

Publisher: Informa UK Limited

Date: 16-03-2014

DOI: 10.1080/07924259.2020.1764117

Evidence for placental transfer of lipids during gestation in the viviparous lizard, Pseudemoia entrecasteauxii

Publisher: Elsevier BV

Date: 10-2004

DOI: 10.1016/J.CBPB.2004.09.004

Abstract: During gestation in the viviparous lizard Pseudemoia entrecasteauxii, the fetus obtains nutrients from two sources: uptake of yolk components from the retained egg (lecithotrophy) and transfer of nutrients from the maternal circulation via the placenta (placentotrophy). Although net placentotrophy in this species is indicated by the observation that the neonate contains 1.7 times more dry matter than the egg, the placental transfer of lipid has not been previously demonstrated. Lipid analysis was performed on newly ovulated eggs and on neonates. The weight of total lipid per neonate (8.2+/-0.5 mg) is significantly (P=0.049) greater than that in the egg (6.8+/-0.4 mg), indicating that the placenta must contribute some lipid to the fetus. On the assumption that 50% of the lipid delivered to the fetus from either source is oxidized for energy, it is calculated that the placenta accounts for 58.5% of the fetal lipid requirements, with the remaining 41.5% being derived from the egg. The fatty acid compositions of the triacylglycerol and phospholipid recovered in the neonatal tissue differ substantially from those of the egg. In particular, the proportions of 18:2n-6 and 18:3n-3 are far lower in the neonatal lipids compared with the egg lipids. On the other hand, the proportion of 22:6n-3 in the phospholipid of the neonate is six times higher than in the phospholipid of the egg. The absolute amount (mg) of 22:6n-3 recovered in the total lipid of the neonate is 3.8 times greater than the amount initially present in the egg. By comparison, the amount of total fatty acid in neonatal lipid is 1.2 times greater than the amount in the egg. Thus, there is a preferential use of 22:6n-3 for tissue phospholipid synthesis during development. We conclude that there is net transfer of fatty acids across the placenta to the fetus of P. entrecasteauxii and a high degree of selectivity in the use of the various fatty acids for fetal tissue lipid synthesis.

Divergent introduction histories among invasive populations of the delicate skink (Lampropholis delicata): Has the importance of genetic admixture in the success of biological invasions been overemphasized?

Publisher: Wiley

Date: 19-05-2013

DOI: 10.1111/J.1472-4642.2012.00919.X

Energy density and its seasonal variation in desert beetles

Publisher: Elsevier BV

Date: 02-2004

DOI: 10.1016/S0140-1963(03)00079-X

Daily Patterns of Metabolic Rate among New Zealand Lizards (Reptilia: Lacertilia: Diplodactylidae and Scincidae)

Publisher: University of Chicago Press

Date: 07-2006

DOI: 10.1086/504618

Abstract: In addition to the effects of temperature fluctuations on metabolic rate, entrained endogenous rhythms in metabolism, which are independent of temperature fluctuations, may be important in overall energy metabolism in ectotherms. Daily entrained endogenous rhythms may serve as energy-conserving mechanisms during an animal's active or inactive phase. However, because nocturnal lizards often take advantage of thermal opportunities during the photophase (light), their daily metabolic rhythms may be less pronounced than those of diurnal species. We measured the rate of oxygen consumption (VO(2)) as an index of metabolic rate of eight temperate lizard species (four nocturnal, three diurnal, and one crepuscular/diurnal n = 7-14) over 24 h at 13 degrees C and in constant darkness to test whether daily patterns (including litude, magnitude, and time of peak VO(2)) of metabolic rate in lizards differ with activity period. We also tested for phylogenetic differences in metabolic rate between skinks and geckos. Three daily patterns were evident: 24-h cycle, 12-h cycle, or no daily cycle. The skink Cyclodina aenea has a 12-h crepuscular pattern of oxygen consumption. In four other species, VO(2) increased with, or in anticipation of, the active part of the day, but three species had rhythms offset from their active phase. Although not correlated with activity period or phylogeny, litude of VO(2) may be correlated with whether a species is temperate or tropical. In conclusion, the metabolic rate of many species does not always correlate with the recorded activity period. The dichotomy of ecology and physiology may be clarified by more in-depth studies of species behaviors and activity periods.

Uterine focal adhesion dynamics during pregnancy in a marsupial (Sminthopsis crassicaudata; Dasyuridae)

Publisher: Wiley

Date: 07-02-2017

DOI: 10.1002/AR.23535

Abstract: Alterations to the basal attachment points between the epithelium of the uterus and the underlying tissue in early pregnancy affect how easily the epithelium can be invaded by the implanting embryo. Attachment points- focal adhesions- disassemble to facilitate highly invasive implantation in rats, but species with less invasive implantation, including marsupials, may require different basal alterations for successful pregnancy. Here we used immunofluorescence microscopy and Western blotting to conduct the first study of basal plasma membrane dynamics in the uterus during marsupial pregnancy. We describe localisation patterns of two key anchoring molecules, talin and paxillin, throughout pregnancy in the fat-tailed dunnart (Sminthopsis crassicaudata Dasyuridae). Basal staining of both molecules occurs in early pregnancy, as it does in the rat. However, unlike rats, there is strong basal localisation of talin and paxillin just before implantation in S. crassicaudata, indicating that focal adhesions do not disassemble during pregnancy in this species, and that molecular reinforcement of the epithelium may be a maternal strategy to regulate invasion. Additionally, talin and paxillin do not co-localise at all stages of pregnancy as they do in the rat. Different localisation patterns among mammalian species demonstrate that not all early pregnancy changes are ubiquitous in mammalian pregnancy, as changes to the basal plasma membrane of the epithelium, in particular, may instead be dependent on mode of implantation. Anat Rec, 300:1150-1159, 2017. © 2016 Wiley Periodicals, Inc.

Utilisation of lipids, protein, ions and energy during embryonic development of Australian oviparous skinks in the genus Lampropholis

Publisher: Elsevier BV

Date: 06-2001

DOI: 10.1016/S1095-6433(00)00349-4

Abstract: The contents of eggs and neonates of the Australian skinks, L ropholis guichenoti and L. delicata, are described and compared to allow interpretation of nutrient utilisation by the developing embryo. Even though the females are the same size, L. guichenoti lay smaller clutches of larger eggs (egg contents=41.6+/-1.2 mg dry mass) than L. delicata (26.6+/-2.8 mg). The energy density is the same for eggs (30.5+/-0.9 J/g ash-free dry mass for L. guichenoti and 29.9+/-1.1 J/mg for L. delicata) and neonates (22.5+/-1.3 J/mg for L. guichenoti and 23.5+/-0.4 J/mg for L. delicata) between species. The amount of nitrogen (protein) in neonates is only slightly lower than that in eggs, whereas there is a large and significant decline in total lipids. Thus, like some other skinks, protein is a source of metabolic energy during embryogenesis, although not as important as lipid. Triacylglycerol is the major lipid component of the eggs (80% of total lipid), with phospholipid forming only approximately 10% of the total lipid. The fatty acid profile of the phospholipid is distinguished by a high proportion of arachidonic acid (8%), a significant proportion of eicosapentaenoic acid (2-4%) and a relatively low proportion of docosahexaenoic acid (2-3%) compared to chickens. Eggs of both species have remarkably low concentrations of free cholesterol compared to other amniote eggs (0.7% for L. guichenoti and 1.3% for L. delicata). The loss of lipid during embryonic development is almost entirely due to the selective utilisation of yolk triacylglycerol, presumably for energy. By contrast, the amount of phospholipid recovered from the neonates was the same as that originally in the eggs. Moreover, significantly more total cholesterol was present in the neonates than in the eggs, suggesting that biosynthesis of additional cholesterol occurred during development. The phospholipids of the neonates contain higher proportions of arachidonic (11-12%) and docosahexaenoic (8%) acids than the phospholipids of the eggs. Eicosapentaenoic acid is less prevalent in phospholipids in neonates than in eggs. Neonates of both species contain significantly more calcium than the fresh egg contents (L. guichenoti, eggs 0.303+/-0.051 mg, neonates 0.641+/-0.047 mg L. delicata, eggs 0.187+/-0.013 mg, neonates 0.435+/-0.033 mg), presumably as a result of resorption of calcium from the eggshell. Interestingly, there is also significantly more sodium in neonates than in the contents of fresh eggs (L. guichenoti, eggs 0.094+/-0.010 mg, neonates 0.184+/-0.011 mg L. delicata, eggs 0.084+/-0.011 mg, neonates 0.151+/-0.010 mg). There is no significant difference in the content of potassium and magnesium in eggs and neonates of either species. Although the fresh eggs of L. delicata have a significantly higher sodium concentration than L. guichenoti, there is no difference in the concentrations of calcium, magnesium, potassium or sodium in the neonates of the two species.

Thermal biology of a viviparous lizard with temperature-dependant sex determination

Publisher: Elsevier BV

Date: 05-2006

DOI: 10.1016/J.JTHERBIO.2005.11.031

Epidermal differentiation during ontogeny and after hatching in the snakeLiasis fuscus (Pythonidae, Serpentes, Reptilia), with emphasis on the formation of the shedding complex

Publisher: Wiley

Date: 04-02-2003

DOI: 10.1002/JMOR.10071

Abstract: Differentiation and localization of keratin in the epidermis during embryonic development and up to 3 months posthatching in the Australian water python, Liasis fuscus, was studied by ultrastructural and immunocytochemical methods. Scales arise from dome-like folds in the skin that produce tightly imbricating scales. The dermis of these scales is completely differentiated before any epidermal differentiation begins, with a loose dermis made of mesenchymal cells beneath the differentiating outer scale surface. At this stage (33) the embryo is still unpigmented and two layers of suprabasal cells contain abundant glycogen. At Stage 34 (beginning of pigmentation) the first layers of cells beneath the bilayered periderm (presumptive clear and oberhautchen layers) have not yet formed a shedding complex, within which prehatching shedding takes place. At Stage 35 the shedding complex, consisting of the clear and oberhautchen layers, is discernible. The clear layer contains a fine fibrous network that faces the underlying oberhautchen, where the spinulae initially contain a core of fibrous material and small beta-keratin packets. Differentiation continues at Stage 36 when the beta-layer forms and beta-keratin packets are deposited both on the fibrous core of the oberhautchen and within beta-cells. Mesos cells are produced from the germinal layer but remain undifferentiated. At Stage 37, before hatching, the beta-layer is compact, the mesos layer contains mesos granules, and cells of the alpha-layer are present but are not yet keratinized. They are still only partially differentiated a few hours after hatching, when a new shedding complex is forming underneath. Using antibodies against chick scale beta-keratin resolved at high magnification with immunofluorescent or immunogold conjugates, we offer the first molecular confirmation that in snakes only the oberhautchen component of the shedding complex and the underlying beta cells contain beta-keratin. Initially, there is little immunoreactivity in the small beta-packets of the oberhautchen, but it increases after fusion with the underlying cells to produce the syncytial beta layer. The beta-keratin packets coalesce with the tonofilaments, including those attached to desmosomes, which rapidly disappear in both oberhautchen and beta-cells as differentiation progresses. The labeling is low to absent in forming mesos-cells beneath the beta-layer. This study further supports the hypothesis that the shedding complex in lepidosaurian reptiles evolved after there was a segregation between alpha-keratogenic cells from beta-keratogenic cells during epidermal renewal.

Changes to the uterine epithelium during the reproductive cycle of two viviparous lizard species (Niveoscincus spp.)

Publisher: Wiley

Date: 04-09-2014

DOI: 10.1111/AZO.12096

Uterine Receptivity in Merriam's Kangaroo Rat (Dipodomys merriami).

Publisher: Wiley

Date: 05-10-2018

DOI: 10.1002/AR.23891

Abstract: The uterine surface undergoes significant remodeling, termed the "plasma membrane transformation," during pregnancy to allow for implantation of the blastocyst and formation of the placenta in viviparous amniote vertebrates. Unlike other species within the superorder Euarchontoglires, which have a hemochorial (highly invasive) placenta, kangaroo rats (Dipodomys spp.) exhibit a less invasive endotheliochorial placenta. We characterized the changes that occur to membrane molecules and the cellular ultrastructure of the uterine epithelium during early pregnancy in Merriam's kangaroo rat, Dipodomys merriami using electron microscopy and immunofluorescence microscopy. Epithelial cadherin (E-cadherin) is an adhesion protein that forms the adherens junction and is localized to the lateral plasma membrane of uterine epithelium during the nonreproductive state but localizes nonspecifically in the uterine epithelium immediately preceding implantation. Desmosomes are a type of cadherin that form junctional complexes along the lateral plasma membrane of epithelium. Dsg-2, a marker for desmosomes, is localized along the lateral plasma membrane in non-pregnant animals but redistributes to the apical region of the lateral plasma membrane during early pregnancy. The shift in desmosome and cadherin distribution before implantation suggests that there is a reduction in lateral adhesion between epithelial cells to allow for invasion by the blastocyst. Surprisingly, although Kangaroo rats form a less invasive placenta, these same changes occur during pregnancy in species with highly invasive placentation, such as the laboratory rat and human. These commonalities suggest that it is not through the retention of lateral adhesion that the blastocyst is prevented from further invasion in this rodent species. Anat Rec, 301:1928-1935, 2018. © 2018 Wiley Periodicals, Inc.

Uptake of dextran-FITC by epithelial cells of the chorioallantoic placentome and the omphalopleure of the placentotrophic lizard, Pseudemoia entrecasteauxii

Publisher: Wiley

Date: 10-2006

DOI: 10.1002/JEZ.A.328

Abstract: Placental nutrient provision has evolved in multiple lineages of squamate reptiles and although possible structural specializations for placentotrophy have been described in a variety of species, neither the pathways nor the mechanisms of placental transfer are known. Lizards of the Australian genus Pseudemoia are placentotrophic and have elaborate placental structures that are thought to enhance nutrient transfer. The chorioallantoic placenta, which occupies the embryonic hemisphere of the egg, is regionally ersified into a large area with low epithelial height and a smaller placentome with cuboidal or columnar epithelia. Both regions are underlain by an extensive vascular bed. The abembryonic hemisphere of the egg is covered by an omphaloplacenta, which is similar to the placentome in having cuboidal or columnar epithelia but with a different embryonic vascular supply. We tested the hypothesis that embryonic epithelial cells of the placentome and the omphaloplacenta of Pseudemoia entrecasteauxii are each capable of endocytosis. Embryos (stages 33-39) with intact extraembryonic membranes were surgically removed from the uterus and incubated in a solution containing fluorescein isothiocyanate-dextran (77,000 MW). The fluorescent label was detected in the cytoplasm of scattered populations of epithelial cells in both placental regions of all embryonic stages. We conclude that both the placentome and the omphaloplacenta of P. entrecasteauxii are sites of histotrophic nutrient transport. However, there are histological and cytological differences in the embryonic epithelia of these two placental regions. The histological differences reflect differences in the evolutionary precursors of each tissue. The cytological differences likely portray different functional specializations.

Uterine Epithelial Cells Undergo a Plasma Membrane Transformation During Early Pregnancy in the Domestic Cat (Felis catus).

Publisher: Wiley

Date: 09-2018

DOI: 10.1002/AR.23895

Abstract: Mammals exhibit similar changes in uterine epithelial morphology during early pregnancy despite having a erse range of placental types. The uterine epithelium undergoes rapid morphological and molecular change ("plasma membrane transformation") during the early stages of pregnancy to allow attachment of the blastocyst. The domestic cat, Felis catus is in the order Carnivora all species within the Carnivora studied so far develop an endotheliochorial placenta during pregnancy. The endotheliochorial placental type is a common form of placental invasion in mammals. The molecular changes that allow remodeling of the uterine epithelium in preparation for implantation are unknown in most mammals but would provide us with an understanding of what molecules underpin successful implantation and pregnancy among Carnivora. We used immunofluorescence microscopy to localize the key adherens junction proteins desmoglein-2 and E-cadherin in the lateral plasma membrane of the uterine epithelium of F. catus during pregnancy. We show that redistribution of desmoglein-2 and E-cadherin likely facilitates reduction of cell-to-cell adhesion allowing for implantation of the blastocyst and formation of the placenta. The ultrastructural and molecular changes to the uterine epithelium during early pregnancy in F. catus are similar to that in species with other levels of placental invasiveness, suggesting that key molecules such as desmoglein-2 and E-cadherin are crucial to successful pregnancy across all mammals. Anat Rec, 301:1497-1505, 2018. © 2018 Wiley Periodicals, Inc.

Evolution of placentotrophy: using viviparous sharks as a model to understand vertebrate placental evolution

Publisher: CSIRO Publishing

Date: 2019

DOI: 10.1071/MF18076

Abstract: Reproducing sharks must provide their offspring with an adequate supply of nutrients to complete embryonic development. In oviparous (egg-laying) sharks, offspring develop outside the mother, and all the nutrients required for embryonic growth are contained in the egg yolk. Conversely, in viviparous (live-bearing) sharks, embryonic development is completed inside the mother, providing offspring with the opportunity to receive supplementary embryonic nourishment, known as matrotrophy. Viviparous sharks exhibit nearly all forms of matrotrophy known in vertebrates, including a yolk-sac placenta, which involves several significant ontogenetic modifications to fetal and maternal tissues. The selective pressures that have driven the evolution of complex placentas in some shark species, but not in others, are unresolved. Herein we review the mechanisms of reproductive allocation and placental ersity in sharks, and consider the application of both adaptive and conflict hypotheses for the evolution of placental nutrient provisioning. Both have likely played roles in placental evolution in sharks, perhaps at different times in evolutionary history. Finally, we recommend sharks as an outstanding model system to investigate the evolution of placentas and mechanisms for fetal nutrition during pregnancy in vertebrates.

Low Cost of Locomotion in Lizards That Are Active at Low Temperatures

Publisher: University of Chicago Press

Date: 2007

DOI: 10.1086/509237

Abstract: The nocturnality hypothesis of K. Autumn and coworkers states that nocturnal geckos have evolved a low energetic cost of locomotion (C(min)). A low C(min) increases maximum aerobic speed and partially offsets the decrease in maximum oxygen consumption caused by activity at low nocturnal temperatures. We tested whether a low C(min) is unique to nocturnal geckos or represents a more general pattern of convergent evolution among lizards that enables nocturnality and/or cold-temperature activity. We measured C(min) in four carefully selected lizard species from New Zealand (two nocturnal and two diurnal n=5-9 in iduals per species), including a nocturnal and diurnal gecko (a low C(min) is a gecko trait and is not related to nocturnality), a nocturnal skink (a low C(min) is related to being nocturnal), and a diurnal skink active at low temperatures (a low C(min) is related to being active at low body temperatures). The C(min) values of the four species measured in this study (range=0.21-2.00 mL O(2) g(-1) km(-1)) are lower than those of diurnal lizards from elsewhere, and the values are within or below the 95% confidence limits previously published for nocturnal geckos. A low C(min) increases the range of locomotor speeds possible at low temperatures and provides an advantage for lizards active at these temperatures. We accepted the hypothesis that nocturnal lizards in general have a low C(min) and provide evidence for a low C(min) in lizards from cool-temperate environments. The low C(min) in lizards living at high latitudes may enable extension of their latitudinal range into otherwise thermally suboptimal habitats.

Changes in participant behaviour and attitudes are associated with knowledge and skills gained by using a turtle conservation citizen science app

Publisher: Wiley

Date: 25-01-2021

DOI: 10.1002/PAN3.10184

Uterine and eggshell structure and histochemistry in a lizard with prolonged uterine egg retention (Lacertilia, Scincidae, Saiphos)

Publisher: Wiley

Date: 16-08-2010

DOI: 10.1002/JMOR.10877

Abstract: The eggshell of lizards is a complex structure composed of organic and inorganic molecules secreted by the oviduct, which protects the embryo by providing a barrier to the external environment and also allows the exchange of respiratory gases and water for life support. Calcium deposited on the surface of the eggshell provides an important nutrient source for the embryo. Variation in physical conditions encountered by eggs results in a tradeoff among these functions and influences eggshell structure. Evolution of prolonged uterine egg retention results in a significant change in the incubation environment, notably reduction in efficiency of gas exchange, and selection should favor a concomitant reduction in eggshell thickness. This model is supported by studies that demonstrate an inverse correlation between eggshell thickness and length of uterine egg retention. One mechanism leading to thinning of the eggshell is reduction in size of uterine shell glands. Saiphos equalis is an Australian scincid lizard with an unusual pattern of geographic variation in reproductive mode. All populations retain eggs in the uterus beyond the embryonic stage at oviposition typical for lizards, and some are viviparous. We compared structure and histochemistry of the uterus and eggshell of two populations of S. equalis, prolonged egg retention, and viviparous to test the hypotheses: 1) eggshell thickness is inversely correlated with length of egg retention and 2) eggshell thickness is positively correlated with size of shell glands. We found support for the first hypothesis but also found that eggshells of both populations are surprisingly thick compared with other lizards. Our histochemical data support prior conclusions that uterine shell glands are the source of protein fiber matrix of the eggshell, but we did not find a correlation between size of shell glands and eggshell thickness. Eggshell thickness is likely determined by density of uterine shell glands in this species.

Changing distribution of cadherins during gestation in the uterine epithelium of lizards

Publisher: Wiley

Date: 24-05-2011

DOI: 10.1002/JEZ.B.21419

Abstract: The uterine epithelium provides the interface between an embryo and its mother during pregnancy. Calcium-dependent cadherins are adherens junction proteins that undergo major shifts in the uterine epithelium to facilitate the communication between maternal cells and the embryonic milieu during implantation in mammals. They are, therefore, important in trophoblast invasion and the maintenance of pregnancy. We investigated spatiotemporal changes of cadherins throughout pregnancy in the uterine epithelium of two viviparous skinks and one oviparous population, which all exhibit a noninvasive (epitheliochorial) placenta. Cadherins were identified for the first time in squamate reptiles. In all species, cadherins are reduced in the uterine epithelium as gestation progresses, which would lessen the attachment between uterine epithelial cells and allow them to stretch to accommodate embryonic growth. Interestingly, cadherins were reduced sooner after ovulation in the oviparous species than in the viviparous species. In viviparous species, the different expression of cadherins between barren and pregnant uteri from the same mother indicates that expression of cadherins may not be driven solely by maternal hormones, but also by the presence of an embryo. The redistribution of cadherins in squamates is comparable to that of mammals, reflecting establishment of feto-maternal communication during the peri-implantation period. As there is no breaching of maternal tissue in lizards, the change in adherens junctional properties are thus not exclusive to mammals with invasive placentae, which suggests that similar molecular mechanisms regulate changes to uterine epithelia during pregnancy across placental types.

Evolutionary transformations of the fetal membranes of viviparous reptiles: A case study of two lineages

Publisher: Wiley

Date: 25-08-2003

DOI: 10.1002/JEZ.A.10288

Abstract: The reptilian placenta is a composite structure formed by a functional interaction between extraembryonic membranes and the maternal uterus. Study of placental structure of squamate reptiles over the past century has established that each of the multiple independent origins of placentation, which characterize the reproductive ersity of squamates, has resulted from the evolutionary transformation of these homologous structures. Because each evolutionary transformation is an independent novel relationship between maternal and embryonic tissues, the resulting placentae are not homologous, even though the in idual components may be. The evolution of reptilian placentation should reveal much about evolutionary patterns and mechanisms because similar structural-functional systems have been transformed along parallel trajectories on multiple occasions. We compared extraembryonic membrane and placental development and pattern of embryonic nutrition in thamnophiine snakes and Pseudemoia lizards in the context of recent hypotheses of phylogenetic relationships. Two primary types of placentation, chorioallantoic and yolk sac, evolved in each lineage. Smooth, highly vascular regions of chorioallantoic placentation are indistinguishable homoplasies that evolved in parallel, likely to facilitate respiratory exchange. The yolk sac placenta of each lineage is specialized for histotrophic nutrient transfer, yet composition of these structures differs because of variation in the ancestral snakes and lizards. In addition, the omphalopleure that contributes to yolk sac placentation persists to later embryonic stages compared to oviparous outgroups, but the two lineages have evolved different structures that prevent replacement of the omphalopleure by the allantois. Each lineage has also evolved unique structural specializations of the chorioallantoic placenta.

Placental calcium provision in a lizard with prolonged oviductal egg retention

Publisher: Springer Science and Business Media LLC

Date: 09-2009

DOI: 10.1007/S00360-009-0400-2

Abstract: A prominent scenario for the evolution of viviparity and placentation in reptiles predicts a step-wise pattern with an initial phase of prolonged oviductal egg retention accompanied by progressive reduction in eggshell thickness culminating in viviparity calcium placentotrophy evolves secondarily to viviparity. Saiphos equalis is an Australian scincid lizard with a reproductive mode that is uncommon for squamates because eggs are retained in the oviduct until late developmental stages, and the embryonic stage at oviposition varies geographically. We studied calcium mobilization by embryos in two populations with different oviductal egg retention patterns to test the hypothesis that the pattern of nutritional provision of calcium is independent of the embryonic stage at oviposition. Females from one population are viviparous and oviposit eggs containing fully formed embryos, whereas embryos in oviposited eggs of the second population are morphologically less mature, and these eggs hatch several days later. The reproductive mode of this population is denoted as prolonged oviductal egg retention. Yolk provided the highest proportion of calcium to hatchlings in both populations. Eggs of both populations were enclosed in calcified eggshells, but shells of the population with prolonged egg retention had twice the calcium content of the viviparous population and embryos recovered calcium from these eggshells. Placental transfer accounted for a substantial amount of calcium in hatchlings in both populations. Hatchling calcium concentration was higher in the population with prolonged egg retention because these embryos mobilized calcium from yolk, the eggshell and the placenta. This pattern of embryonic calcium provision in which both a calcified eggshell and placentotrophy contribute to embryonic nutrition is novel. The reproductive pattern of S. equalis illustrates that calcified eggshells are compatible with prolonged oviductal egg retention and that viviparity is not requisite to calcium placentotrophy.

Facultative oviparity in a viviparous skink ( Saiphos equalis )

Publisher: The Royal Society

Date: 04-2019

DOI: 10.1098/RSBL.2018.0827

Abstract: Facultative changes in parity mode (oviparity to viviparity and vice versa) are rare in vertebrates, yet offer fascinating opportunities to investigate the role of reproductive lability in parity mode evolution. Here, we report apparent facultative oviparity by a viviparous female of the bimodally reproductive skink Saiphos equalis —the first report of different parity modes within a vertebrate clutch. Eggs oviposited facultatively possess shell characteristics of both viviparous and oviparous S. equalis , demonstrating that egg coverings for viviparous embryos are produced by the same machinery as those for oviparous in iduals. Since selection may act in either direction when viviparity has evolved recently, squamate reproductive lability may confer a selective advantage. We suggest that facultative oviparity is a viable reproductive strategy for S. equalis and that squamate reproductive lability is more evolutionarily significant than previously acknowledged.

The biomechanical, chemical and physiological adaptations of the eggs of two Australian megapodes to their nesting strategies and their implications for extinct titanosaur dinosaurs

Publisher: Wiley

Date: 30-05-2017

DOI: 10.1111/JMI.12572

Abstract: Megapodes are galliform birds endemic to Australasia and unusual among modern birds in that they bury their eggs for incubation in erse substrates and using various strategies. Alectura lathami and Leipoa ocellata are Australian megapodes that build and nest in mounds of soil and organic matter. Such unusual nesting behaviours have resulted in particular evolutionary adaptations of their eggs and eggshells. We used a combination of scanning electron microscopy, including electron backscatter diffraction and energy-dispersive X-ray spectroscopy, to determine the fine structure of the eggshells and micro-CT scanning to map the structure of pores. We discovered that the surface of the eggshell of A. lathami displays nodes similar to those of extinct titanosaur dinosaurs from Transylvania and Auca Mahuevo egg layer #4. We propose that this pronounced nodular ornamentation is an adaptation to an environment rich in organic acids from their nest mound, protecting the egg surface from chemical etching and leaving the eggshell thickness intact. By contrast, L. ocellata nests in mounds of sand with less organic matter in semiarid environments and has eggshells with weakly defined nodes, like those of extinct titanosaurs from AM L#3 that also lived in a semiarid environment. We suggest the internode spaces in both megapode and titanosaur species act as funnels, which concentrate the condensed water vapour between the nodes. This water funnelling in megapodes through the layer of calcium phosphate reduces the likelihood of bacterial infection by creating a barrier to microbial invasion. In addition, the accessory layer of both species possesses sulphur, which reinforces the calcium phosphate barrier to bacterial and fungal contamination. Like titanosaurs, pores through the eggshell are Y-shaped in both species, but A. lathami displays unique mid-shell connections tangential to the eggshell surface and that connect some adjacent pores, like the eggshells of titanosaur of AM L#4 and Transylvania. The function of these interconnections is not known, but likely helps the diffusion of gases in eggs buried in environments where occlusion of pores is possible.

Placental development and expression of calcium transporting proteins in the extraembryonic membranes of a placentotrophic lizard

Publisher: Wiley

Date: 24-10-2011

DOI: 10.1002/JMOR.11030

Abstract: Pseudemoia pagenstecheri is a viviparous Australian scincid lizard in which the maternal-embryonic placental interface is differentiated into structurally distinct regions. The chorioallantoic placenta contains an elliptical-shaped region, the placentome, characterized by hypertrophied uterine and embryonic epithelial cells supported by dense vascular networks. The remainder of the chorioallantoic placenta, the paraplacentome, is also highly vascularized but uterine and chorionic epithelia are thin. An omphaloplacenta with hypertrophied epithelia is located in the abembryonic hemisphere of the egg. There is extensive placental transport of organic and inorganic nutrients, e.g., 85-90% of neonatal calcium is received via placental transfer. Calcium uptake by extraembryonic membranes of squamates correlates with expression of the intracellular calcium binding protein, calbindin-D(28K) , and plasma membrane calcium ATPase (PMCA) is a marker for active calcium transport. We estimated expression of calbindin-D(28K) and PMCA in the chorioallantoic membrane in a developmental series of embryos using immunoblotting and used immunohistochemistry to define the cellular localization of calbindin-D(28K) to test the hypotheses that 1) expression of calcium transporting proteins is coincident with placental transport of calcium and 2) the placenta is functionally specialized for calcium transport in regions of structural differentiation. Calbindin-D(28K) and PMCA were detected at low levels in early stages of development and increased significantly prior to birth, when embryonic calcium uptake peaks. These data support the hypothesis that placental calcium secretion occurs over an extended interval of gestation, with increasing activity as embryonic demand escalates in late development. In addition, calbindin-D(28K) expression is localized in chorionic epithelial cells of the placentome and in the epithelium of the omphalopleure of the omphaloplacenta, which supports the hypothesis that regional structural differentiation in the placenta reflects functional specializations for calcium transport.

Comparison of the respiratory transition at birth or hatching in viviparous and oviparous amniote vertebrates

Publisher: Elsevier BV

Date: 12-2007

DOI: 10.1016/J.CBPA.2007.01.006

Abstract: Regardless of the mode of reproduction, three things must occur at birth or hatching in amniote vertebrates: initiation of breathing, pulmonary fluid elimination and reabsorption, and adequate perfusion of pulmonary circulation. Although data on these events are few, there appears to be no fundamental difference in them that can be associated with the oviparity to viviparity transition. There are, however, differences in the timing of these events in oviparous and viviparous amniotes. The transition to neonatal respiration tends to be very quick in viviparous species because the vascular support for oxygen uptake provided by the mother is rapidly disassociated from the mechanism for uptake by the embryo. By contrast, hatching often is a slow process, taking 24 h or more in some species, as chorioallantoic blood flow slowly gives way to clearing of the lungs and pulmonary gas exchange. Little is known of the mechanisms of pulmonary fluid elimination and reabsorption or lung inflation in reptiles, but the cellular structures and surfactant systems are similar in all amniote vertebrates. Nevertheless, there are differences, particularly of timing and maturation of various systems, but there has been no exploration of the functional (or phylogenetic) bases of these differences. Perfusion of the neonatal pulmonary system to support respiration in reptiles remains to be investigated. In mammals and birds, closure of the ductus arteriosus is important, but the role played by the ductus arterioisus in reptilian hatching or birth is not known.

Claudin-5 is restricted to the tight junction region of uterine epithelial cells in the uterus of pregnant/gravid squamate reptiles

Publisher: Wiley

Date: 02-04-2008

DOI: 10.1002/AR.20677

Abstract: Claudin-5, a tight junctional protein associated with ion and size selectivity, has been found in the uterus of skinks. This study has generated critical information about the molecular assembly of the tight junction at various stages of the reproductive cycle in the skink uterus. Recent studies looking at tight junctional proteins found occludin expression in the tight junction region of uterine epithelial cells in the skink uterus however, occludin did not disclose any further information about the ions and size of ions permeating across the paracellular pathway. A approximately 22-kDa claudin-5 band was detected in the uterus of the skinks present in this study and immunohistochemistry revealed that claudin-5 redistributes to the tight junction region of the lateral plasma membrane of uterine epithelial cells in late stage pregnancy/gravidity. This finding indicates that the tight junction becomes more assembled to precisely regulate ion and solute permeation in late stage pregnancy/gravidity. Claudin-5 with its functional role as a molecular sieve due to the formation of ion and size selective pores suggests that permeation of ions smaller than 0.8 kDa are restricted when claudin-5 is redistributed to the tight junction region of the later plasma membrane. This report is the first description of the molecular mechanisms that may be involved in regulating nutrient provision in the reptilian uterus.

When hot rocks get hotter: behavior and acclimatization mitigate exposure to extreme temperatures in a spider

Publisher: Wiley

Date: 05-2015

DOI: 10.1890/ES14-00436.1

Habitat selection and web plasticity by the orb spider Argiope keyserlingi (Argiopidae): Do they compromise foraging success for predator avoidance?

Publisher: Wiley

Date: 20-06-2007

DOI: 10.1111/J.1442-9993.2007.01727.X

Energetic cost of a meal in a frequent feeding lizard

Publisher: Elsevier BV

Date: 07-2003

DOI: 10.1016/S1095-6433(03)00076-X

Abstract: Specific dynamic action (SDA) describes the rise in metabolism following feeding in animals and represents the energetic cost of digesting and assimilating a meal. The overall energetic cost of feeding may depend on whether or not an animal is post-absorptive at the time of feeding. The aim of this study was to compare the energetic cost of SDA due to feeding frequently compared with infrequently in the eastern water skink, Eul rus quoyii. For similar quantities of food, repeated feeding incurred an energetic cost equal to 8.8% of the metabolizable energy of the meal (25,220 J), while single feeding incurred an energetic cost of 9.4% of the metabolizable energy of the meal (26,072 J). Experimental lizards maintained a rise in (VO2) that was on average 1.8 times greater than the (VO2) of the unfed controls over a 50-h interval as a result of feeding frequently. This prolonged rise in metabolism resulting from frequent feeding does not result in a higher energetic cost of SDA compared with that resulting from infrequent single feeding.

Carbonic anhydrase II is found in the placenta of a viviparous, matrotrophic lizard and likely facilitates embryo-maternal CO2 transport

Publisher: Wiley

Date: 07-06-2015

DOI: 10.1002/JEZ.B.22621

Abstract: The evolution of viviparity requires the development of mechanisms that facilitate transport of respiratory gases between mother and developing embryo. Of particular importance is maternal excretion of embryonic carbon dioxide (CO2 ), which increases as the embryo grows in size during development. The carbonic anhydrases are a family of enzymes that convert CO2 to bicarbonate for transport throughout the cardiovascular system and which may also be important for CO2 transport from embryo to mother. We used immunohistochemistry to localize carbonic anhydrase II in the placental tissues of a viviparous and highly placentotrophic lizard, Pseudemoia entrecasteauxii. Carbonic anhydrase II is localized in the uterine component of the paraplacentome, presumably to facilitate transport of embryonic CO2 to the mother. Carbonic anhydrase II is also localized in both the uterine and embryonic components of the placentome, a region heavily involved in placental nutrient transport rather than respiratory gas exchange. In contrast, carbonic anhydrase II is not present in the uterine or embryonic components of the omphaloplacenta, another region responsible for nutrient transport. While carbonic anhydrase II in the paraplacentomal uterus is likely to be responsible for embryo-maternal CO2 transport, the distribution of carbonic anhydrase II throughout the placentome indicates a different function. Instead of transporting embryonic CO2 , placentomal carbonic anhydrase II appears to be responsible for transporting CO2 produced by energetically expensive nutrient transport mechanisms in both the uterus and the embryo, which implies that the mechanisms of nutrient transport in the omphaloplacenta may not be as energetically expensive.

Transcriptomic changes in the pre-implantation uterus highlight histotrophic nutrition of the developing marsupial embryo

Publisher: Springer Science and Business Media LLC

Date: 05-02-2018

DOI: 10.1038/S41598-018-20744-Z

Abstract: Early pregnancy is a critical time for successful reproduction up to half of human pregnancies fail before the development of the definitive chorioallantoic placenta. Unlike the situation in eutherian mammals, marsupial pregnancy is characterised by a long pre-implantation period prior to the development of the short-lived placenta, making them ideal models for study of the uterine environment promoting embryonic survival pre-implantation. Here we present a transcriptomic study of pre-implantation marsupial pregnancy, and identify differentially expressed genes in the Sminthopsis crassicaudata uterus involved in metabolism and biosynthesis, transport, immunity, tissue remodelling, and uterine receptivity. Interestingly, almost one quarter of the top 50 genes that are differentially upregulated in early pregnancy are putatively involved in histotrophy, highlighting the importance of nutrient transport to the conceptus prior to the development of the placenta. This work furthers our understanding of the mechanisms underlying survival of pre-implantation embryos in the earliest live bearing ancestors of mammals.

Unusual angiogenic factor plays a role in lizard pregnancy but is not unique to viviparity

Publisher: Wiley

Date: 03-2015

DOI: 10.1002/JEZ.B.22615

Abstract: Angiogenesis (blood vessel growth), a key process of mammalian pregnancy, facilitates gas exchange and nutrient transport between the mother and the embryo and is regulated by a suite of growth factors. Vascular endothelial growth factor (VEGF) is crucial to this process in pregnant mammals and potentially pregnant squamates (lizards and snakes), as we investigate here. VEGF111 , an unusual and potent angiogenic splice variant of VEGF, increases its expression during pregnancy in the uterus of a viviparous lizard, in parallel with similar increases in uterine angiogenesis during gestation. However, we also find that VEGF111 is expressed in oviparous skinks, and is not ubiquitous among viviparous skinks. Thus, different mechanisms of uterine angiogenesis during pregnancy may evolve concurrent with viviparity in different lizard lineages.

Hatchling short-necked turtles (Emydura macquarii) select aquatic vegetation habitats, but not after one month in captivity

Publisher: Springer Science and Business Media LLC

Date: 02-01-2021

DOI: 10.1007/S10452-020-09813-6

The influence of urbanization on the behaviour of an Australian lizard and the presence of an activity–exploratory behavioural syndrome

Publisher: Wiley

Date: 24-08-2015

DOI: 10.1111/JZO.12288

Biosecurity interceptions of an invasive lizard: origin of stowaways and human-assisted spread within New Zealand

Publisher: Wiley

Date: 03-09-2013

DOI: 10.1111/EVA.12002

Does decoration building influence antipredator responses in an orb-web spider (Argiope keyserlingi) in its natural habitat?

Publisher: CSIRO Publishing

Date: 2007

DOI: 10.1071/ZO06098

Abstract: Antipredator strategies adopted by animals need to compensate for temporal changes. Many orb-web spiders add silk decorations to their webs, which principally attract prey but may attract some predators. To identify their influence on antipredator behaviour in adult female St Andrew’s cross spiders (Argiope keyserlingi) we measured: spider body condition, web characteristics (area, spiral length and decoration building), environmental variables (air temperature, humidity, wind speed, relative prey abundance) and antipredator responses (remaining at the hub, dropping, shifting to the web periphery, or pumping the web) at three distinct periods (July–August, September–October and January–February) in the field. We developed path models from multiple regression analyses to distinguish between factors having direct and indirect effects. We found that even though both antipredator responses and decoration building change over time, antipredator responses and decoration investment are independent. Body condition and wind speed are directly positively associated with pumping frequency, and decoration building is negatively associated with the frequency of remaining at the hub because the likelihood that an object approaching the web is a predator increases if decorations are added. Wind speed is positively associated with antipredator behaviour and decoration building, due to an increased rate of feeding affecting body condition.

Environmentally induced phenotypic plasticity explains hatching synchrony in the freshwater turtle Chrysemys picta

Publisher: Wiley

Date: 07-2018

DOI: 10.1002/JEZ.2217

Abstract: Environmentally cued hatching allows embryos to alter the time of hatching in relation to environment through phenotypic plasticity. Spatially variable temperatures within shallow nests of many freshwater turtles cause asynchronous development of embryos within clutches, yet neonates still hatch synchronously either by hatching early or via metabolic compensation. Metabolic compensation and changes in circadian rhythms presumably enable embryos to adjust their developmental rates to catch up to more advanced embryos within the nest. Hatchlings of the North American freshwater turtle Chrysemys picta usually overwinter within the nest and emerge the following spring, but still hatch synchronously via hatching early. Here, we used rates of oxygen consumption and heart rate profiles to investigate the metabolic rates of clutches of C. picta developing in conditions that result in asynchronous development to determine if compensatory changes in metabolism occur during incubation. Embryos hatched synchronously and displayed circadian rhythms throughout incubation, but exhibited no evidence of metabolic compensation. Phenotypic traits of hatchlings, including body size and righting performance, were also not affected by asynchronous development. We conclude that less developed embryos of C. picta hatch synchronously with their clutch-mates by hatching early, which does not appear to inflict a fitness cost to in iduals. The ultimate mechanism for synchronous hatching in C. picta could be for hatchlings to ensure an optimal overwintering position within the center of the nest. Consequently, immediate fitness costs will not hinder hatchling survival. The geographic location, as well as environmental and genetic factors unique to populations, can all influence hatching behavior in turtles through phenotypic plasticity. Hence, synchronous hatching is an adaptive bet-hedging strategy in turtles, but the mechanisms to achieve it are erse.

Reduced investment in immune function in invasion-front populations of the cane toad (Rhinella marina) in Australia

Publisher: Springer Science and Business Media LLC

Date: 27-11-2012

DOI: 10.1007/S10530-011-0135-3

Non‐invasive placentation in the marsupials Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae) involves redistribution of uterine Desmoglein‐2

Publisher: Wiley

Date: 2018

DOI: 10.1002/MRD.22940

Abstract: In mammalian pregnancy, the uterus is remodeled to become receptive to embryonic implantation. Since non-invasive placentation in marsupials is likely derived from invasive placentation, and is underpinned by intra-uterine conflict between mother and embryo, species with non-invasive placentation may employ a variety of molecular mechanisms to maintain an intact uterine epithelium and to prevent embryonic invasion. Identifying such modifications to the uterine epithelium of marsupial species with non-invasive placentation is key to understanding how conflict is mediated during pregnancy in different mammalian groups. Desmoglein-2, involved in maintaining lateral cell-cell adhesion of the uterine epithelium, is redistributed before implantation to facilitate embryo invasion in mammals with invasive placentation. We identified localization patterns of this cell adhesion molecule throughout pregnancy in two marsupial species with non-invasive placentation, the tammar wallaby (Macropus eugenii Macropodidae), and the brushtail possum (Trichosurus vulpecula Phalangeridae). Interestingly, Desmoglein-2 redistribution also occurs in both M. eugenii and T. vulpecula, suggesting that cell adhesion, and thus integrity of the uterine epithelium, is reduced during implantation regardless of placental type, and may be an important component of uterine remodeling. Desmoglein-2 also localizes to the mesenchymal stromal cells of M. eugenii and to epithelial cell nuclei in T. vulpecula, suggesting its involvement in cellular processes that are independent of adhesion and may compensate for reduced lateral adhesion in the uterine epithelium. We conclude that non-invasive placentation in marsupials involves erse and complementary strategies to maintain an intact epithelial barrier.

Hatching behavior of eastern long-necked turtles ( Chelodina longicollis ): The influence of asynchronous environments on embryonic heart rate and phenotype

Publisher: Elsevier BV

Date: 10-2015

DOI: 10.1016/J.CBPA.2015.06.018

Abstract: Variable temperatures within a nest cause asynchronous development within clutches of freshwater turtle embryos, yet synchronous hatching occurs and is thought to be an important survival strategy for hatchlings. Metabolic compensation and circadian rhythms in heart rates of embryonic turtles indicate the potential of communication between embryos in a nest. Heart rates were used to identify metabolic circadian rhythms in clutches of an Australian freshwater turtle (Chelodina longicollis) and determine whether embryos metabolically compensate and hatch synchronously when incubated in asynchronous environments. The effects of a group environment during incubation on egg development and incubation period were also investigated during the final 3 weeks of development. Chelodina longicollis hatch synchronously and metabolically compensate so that less advanced embryos catch up to more advanced clutch-mates. Heart rates of embryos remained stable from week 4-7 in asynchronous (M=89 bpm) and synchronous (M=92 bpm) groups and declined in the final 2 weeks of incubation (M=72 and 77 bpm). Circadian rhythms were present throughout development and diel heart rates of embryos in asynchronous groups showed less deviation from the mean (M=-0.5 bpm) than synchronous groups (M=-4 bpm). Eggs incubated in groups had a significantly shorter incubation period than eggs incubated in idually. Phenotypic traits including size, performance, and growth of all hatchlings were not affected. Egg position within a turtle nest is important for coordinating development throughout incubation and facilitating synchronous hatching.

Beneficial acclimation: sex specific thermal acclimation of metabolic capacity in the striped marsh frog (Limnodynastes peronii)

Publisher: The Company of Biologists

Date: 15-08-2007

DOI: 10.1242/JEB.008391

Abstract: Reproductive success in thermally varying environments will depend on maintaining metabolic capacity of tissues that are important in mating behaviours. Here we test the hypothesis that cold acclimation will occur in those tissues that are important for reproduction, and that acclimation will be sex specific, reflecting behavioural differences between the sexes. We used the frog Limnodynastes peronii as a model because anurans engage in energetically demanding reproductive behaviour, and many species, including L. peronii, are reproductively active across seasons. Additionally,reproductive behaviours such as calling and lexus are sex specific. We acclimated animals to naturally occurring autumn (15°C, N=10) and summer (25°C, N=10) temperatures. Whole-animal resting oxygen consumption decreased with lowered temperature, but there was no difference in oxygen consumption between acclimation treatments or sexes. However, the respiratory control ratio (RCR) of mitochondria from the liver and external oblique calling muscle increased with cold acclimation. The increase in RCR with thermal acclimation was due to upregulation of state 3 respiration, and not to a decrease in state 4 respiration. Males had higher activity of citrate synthase, β-hydroxyacyl CoA dehydrogenase and cytochrome coxidase than females in the calling (external oblique) muscle, and males also showed thermal acclimation of these enzymes while females did not. Additionally, males had greater activity of metabolic enzymes in the principal muscle (extensor carpi radialis) used during lexus. However, there were no differences in metabolic capacity between sexes in the gastrocnemius muscle and in liver, and both sexes showed significant acclimation of lactate dehydrogenase and cytochrome c oxidase in the former and latter,respectively. In L. peronii, thermal acclimation of metabolic capacities is linked to reproductive success, and reversible phenotypic plasticity therefore confers a selective advantage by extending the temporal and spatial extent of the animals' fundamental niche.

Facultative cardiac responses to regional hypoxia in lizard embryos

Publisher: Elsevier BV

Date: 08-2010

DOI: 10.1016/J.CBPA.2010.04.005

Abstract: In natural nests, the eggs of squamate reptiles (lizards and snakes) sometimes experience unpredictable shifts in oxygen availability as a function of nest flooding, or the details of egg location within a nest. We experimentally investigated whether embryos can facultatively adjust cardiac function to cope with such challenges by imposing regional hypoxia on developing eggs of the scincid lizard Bassiana duperreyi. To do so, we sealed half of the eggshell surface with tissue adhesive. The embryos rapidly responded by increasing heart rates, which they maintained for long periods. The elevated heart rates enabled the embryos not only to survive, but to maintain "normal" metabolic rates, and to hatch at the usual time with unmodified phenotypic traits (e.g., hatchling size, relative heart mass, locomotor speed, post-hatchling survival and growth rates). Turtles and birds with rigid (highly calcified) eggshells show more dramatic ill-effects from hypoxic incubation, suggesting that the thin (and thus, highly gas-permeable) parchment-shelled eggs of most squamates allow more effective embryonic adjustment of oxygen exchange rates in response to externally-imposed hypoxia.

Do pregnant lizards resorb or abort inviable eggs and embryos? Morphological evidence from an Australian skink,Pseudemoia pagenstecheri

Publisher: Wiley

Date: 07-03-2003

DOI: 10.1002/JMOR.10094

Abstract: Although pregnant viviparous squamates are sometimes claimed to be able to resorb inviable eggs and embryos from the uterus, definitive evidence for such resorption is not available. After placing pregnant female Pseudemoia pagenstecheri into conditions under which embryonic development is terminated, we periodically harvested the gravid oviducts and examined them histologically. Females contained abnormal and degenerating eggs and embryos that had died in various stages of development. Dead embryos had undergone extensive cytolysis, dissolution, and aseptic necrosis and vitelline masses showed signs of deterioration and passage down the oviduct. The uterine mucosa lay in direct contact with the vitelline material, with no intact shell membrane intervening between them. Yolk was sometimes displaced into the exocoelom and allantoic cavity due to rupture of the extraembryonic membranes. Histological examination revealed no evidence of the uptake of yolk by the uterine epithelium or its accumulation in the subepithelial connective tissue. In many specimens, the uterine epithelium showed minuscule, apical granules. The position, appearance, and staining properties of the granules suggests them to be secretory, a manifestation of placentotrophy. Our observations indicate that P. pagenstecheri females retain dead eggs and embryos for several weeks or longer, yet do not resorb them during that period. This lizard is the second placentotrophic skink species in which resorption has been suspected, but in which abortive eggs appear to be retained or extruded instead of being resorbed by the oviducts. Researchers should not assume that squamates can digest and resorb oviductal eggs without definitive morphological evidence.

Thermal physiology

Publisher: Wiley

Date: 17-07-2017

DOI: 10.1111/1365-2656.12718

Abstract: Current syndrome research focuses primarily on behaviour with few incorporating components of physiology. One such syndrome is the pace-of-life syndrome (POLS) which describes covariation between behaviour, metabolism, immunity, hormonal response, and life-history traits. Despite the strong effect temperature has on behaviour, thermal physiology has yet to be considered within this syndrome framework. We proposed the POLS to be extended to include a new dimension, the cold-hot axis. Under this premise, it is predicted that thermal physiology and behaviour would covary, whereby in idual positioning along the thermal continuum would coincide with that of the behavioural continuum. This hypothesis was tested by measuring thermal traits of delicate skinks (L ropholis delicata) and linking it to their behaviour. Principal components analysis and structural equation modelling were used to determine if traits were structured within the POLS and to characterize the direction of their interactions. Model results supported the inclusion of the cold-hot axis into the POLS and indicated that thermal physiology was the driver of this relationship, in that thermal traits either constrained or promoted activity, exploration, boldness and social behaviour. This study highlights the need to integrate thermal physiology within a syndrome framework.

The evolution of viviparity: molecular and genomic data from squamate reptiles advance understanding of live birth in amniotes

Publisher: Bioscientifica

Date: 2014

DOI: 10.1530/REP-13-0309

Abstract: Squamate reptiles (lizards and snakes) are an ideal model system for testing hypotheses regarding the evolution of viviparity (live birth) in amniote vertebrates. Viviparity has evolved over 100 times in squamates, resulting in major changes in reproductive physiology. At a minimum, all viviparous squamates exhibit placentae formed by the appositions of maternal and embryonic tissues, which are homologous in origin with the tissues that form the placenta in therian mammals. These placentae facilitate adhesion of the conceptus to the uterus as well as exchange of oxygen, carbon dioxide, water, sodium, and calcium. However, most viviparous squamates continue to rely on yolk for nearly all of their organic nutrition. In contrast, some species, which rely on the placenta for at least a portion of organic nutrition, exhibit complex placental specializations associated with the transport of amino acids and fatty acids. Some viviparous squamates also exhibit reduced immunocompetence during pregnancy, which could be the result of immunosuppression to protect developing embryos. Recent molecular studies using both candidate-gene and next-generation sequencing approaches have suggested that at least some of the genes and gene families underlying these phenomena play similar roles in the uterus and placenta of viviparous mammals and squamates. Therefore, studies of the evolution of viviparity in squamates should inform hypotheses of the evolution of viviparity in all amniotes, including mammals.

Uterine and Placental Angiogenesis in the Australian Skinks, Ctenotus taeniolatus, and Saiphos equalis

Publisher: Wiley

Date: 23-04-2010

DOI: 10.1002/AR.21052

Abstract: The evolution of viviparity requires modifications to multiple integrated physiological features to support embryonic development during pregnancy. Embryonic growth during pregnancy is dependent upon the capacity of the uterine vascular system to satisfy increasing embryonic oxygen demand throughout gestation. We tested the hypothesis that total surface area of uterine blood vessels increases in concert with embryonic growth, and hence its oxygen demand, during gestation. We used immunofluorescence and laser-scanning confocal microscopy to quantify uterine microvascular density and morphology during gestation in the oviparous skink Ctenotus taeniolatus and in Saiphos equalis, a skink species with prolonged egg retention. For C. taeniolatus, vessel density (Nv) and vessel length-density (Lv) in the embryonic hemisphere of the uterus is 23% and 17% less, respectively, than that of S. equalis and vascular surface-area does not differ as a function of embryo stage. For S. equalis, overall Nv, Lv, and vessel diameter (Dv), does not change during the first half of gestation but increases by 36% (Nv), 44% (Lv), and 60% (Dv) by near-term embryo stages late in gestation. The chorioallantoic membrane of S. equalis increases in absolute size but vascular density does not differ as a function of embryo stage. The marked increase in uterine vascular density during late gestation coincides with the phase of rapid growth in embryo mass and concomitant increase in metabolic rate. Expansion of the uterine vascular bed in concert with embryo size and metabolism is likely to be an important transitional step in the evolution of viviparity.

The Regulation of Uterine Proinflammatory Gene Expression during Pregnancy in the Live‐Bearing Lizard, Pseudemoia entrecasteauxii

Publisher: Wiley

Date: 10-03-2017

DOI: 10.1002/JEZ.B.22733

Abstract: The evolutionary transition from egg-laying to live-bearing in amniote vertebrates (reptiles and mammals) requires the development of a closer association between the maternal and embryonic tissue to facilitate gas and nutrient exchange with the embryo. Because the embryo is an allograft to the father and mother, it could be considered foreign by the maternal immune system and thus be immunologically rejected during pregnancy. In eutherian ("placental") mammals, the proinflammatory genes interleukin 1B (IL1B), tumor necrosis factor (TNF) and tumor necrosis factor receptor superfamily 1A (TNFRSF1A) are tightly regulated in the pregnant uterus to prevent embryonic rejection. We tested whether inflammation is similarly regulated in pregnant viviparous reptiles by comparing the expression of IL1B, TNF, and TNFRSF1A in the pregnant and nonpregnant uterus of the viviparous lizard, Pseudemoia entrecasteauxii. We found statistically significant support for the downregulation of pregnant uterine TNF mRNA expression in P. entrecasteauxii, but no statistically significant changes in mRNA expression of TNFRSF1A or IL1B between pregnant and nonpregnant uteri. Although these genes are apparently not regulated at the transcriptional level, our immunofluorescence microscopy analyses nonetheless demonstrate that the IL1B proteins are stored intracellularly during pregnancy, possibly resulting in inhibition of inflammatory response. We therefore conclude that processes of both transcriptional (TNF) and posttranslational (IL1B) gene regulation may reduce inflammation in the pregnant uterus of this viviparous reptile. Our study is important because it demonstrates that regulating the maternal immune system to prevent embryonic rejection may be important in reptilian pregnancy as it is in mammalian pregnancy.

Ancestral state reconstructions require biological evidence to test evolutionary hypotheses: A case study examining the evolution of reproductive mode in squamate reptiles

Publisher: Wiley

Date: 02-03-2015

DOI: 10.1002/JEZ.B.22614

Abstract: To understand evolutionary transformations it is necessary to identify the character states of extinct ancestors. Ancestral character state reconstruction is inherently difficult because it requires an accurate phylogeny, character state data, and a statistical model of transition rates and is fundamentally constrained by missing data such as extinct taxa. We argue that model based ancestral character state reconstruction should be used to generate hypotheses but should not be considered an analytical endpoint. Using the evolution of viviparity and reversals to oviparity in squamates as a case study, we show how anatomical, physiological, and ecological data can be used to evaluate hypotheses about evolutionary transitions. The evolution of squamate viviparity requires changes to the timing of reproductive events and the successive loss of features responsible for building an eggshell. A reversal to oviparity requires that those lost traits re-evolve. We argue that the re-evolution of oviparity is inherently more difficult than the reverse. We outline how the inviability of intermediate phenotypes might present physiological barriers to reversals from viviparity to oviparity. Finally, we show that ecological data supports an oviparous ancestral state for squamates and multiple transitions to viviparity. In summary, we conclude that the first squamates were oviparous, that frequent transitions to viviparity have occurred, and that reversals to oviparity in viviparous lineages either have not occurred or are exceedingly rare. As this evidence supports conclusions that differ from previous ancestral state reconstructions, our paper highlights the importance of incorporating biological evidence to evaluate model-generated hypotheses.

Chemical Composition and Structure of the Eggshell of Three Oviparous Lizards

Publisher: American Society of Ichthyologists and Herpetologists (ASIH)

Date: 08-2005

DOI: 10.1643/CH-04-280R1

Parallel evolution of placentation in Australian scincid lizards

Publisher: Wiley

Date: 14-11-2008

DOI: 10.1002/JEZ.B.21245

Abstract: Viviparity and placental nutrient provision have evolved on numerous occasions in squamate reptiles. Five lineages are substantially placentotrophic and two of these, the genera Pseudemoia and Niveoscincus, are closely related scincid lizards that have independently evolved viviparity and placentation. Histological comparison of placental ontogeny of placentotrophic species of these genera with development of the extraembryonic membranes of oviparous outgroups indicates a high level of homoplasy. The terminal placental stage of each lineage consists of an omphaloplacenta (yolk sac placenta) and a chorioallantoic placenta and each type of placentation consists of both identical and distinguishable characters. We infer three derived placental functions based on morphology and suggest that the level of structural similarity between lineages results from different evolutionary patterns. Functional characteristics include (1) respiratory exchange regions of chorioallantoic placentation, (2) nutritive exchange regions of the omphaloplacenta, and (3) localized sites of nutritive exchange in the chorioallantoic placenta. Structural similarity in the chorioallantoic placentae for respiration likely resulted from parallel evolutionary trajectories driven by selection to maintain functions characteristic of the eggs of oviparous ancestors. Structural similarity in omphaloplacentation is explainable by selection for nutritional transport developmentally constrained by formation of the isolated yolk mass complex, whereas nutritive sites in the chorioallantoic placentae evolved in the absence of genetic or developmental constraints and differ structurally.

Emergence of an evolutionary innovation: Gene expression differences associated with the transition between oviparity and viviparity

Publisher: Wiley

Date: 04-2020

DOI: 10.1111/MEC.15409

Field metabolic rate and water turnover of red kangaroos and sheep in an arid rangeland: an empirically derived dry-sheep-equivalent for kangaroos

Publisher: CSIRO Publishing

Date: 2009

DOI: 10.1071/ZO08063

Abstract: Sustainable management of pastures requires detailed knowledge of total grazing pressure, but this information is critically lacking in Australia’s rangelands where livestock co-occur with large herbivorous marsupials. We present the first comparative measure of the field metabolic rate (an index of food requirement) of Australia’s largest marsupial, the red kangaroo (Macropus rufus), with that of domestic sheep (Ovis aries merino breed). We tested the assumption that the grazing pressure of red kangaroos is equivalent to 0.7 sheep, and show this to be a two-fold overestimation of their contribution to total grazing. Moreover, kangaroos had extraordinarily lower rates of water turnover, being only 13% that of sheep. Consequently, our data support arguments that the removal of kangaroos may not markedly improve rangeland capacity for domestic stock. Furthermore, given the low resource requirements of kangaroos, their use in consumptive and non-consumptive enterprises can provide additional benefits for Australia’s rangelands than may occur under traditional rangeland practices.

Thermodynamic constraints and the evolution of parental provisioning in vertebrates

Publisher: Oxford University Press (OUP)

Date: 27-03-2019

DOI: 10.1093/BEHECO/ARZ025

MORPHOLOGICAL AND FUNCTIONAL CHANGES TO THE UTERUS OF LIZARDS WITH DIFFERENT PLACENTAL COMPLEXITIES

Publisher: Herpetologists League

Date: 2006

DOI: 10.1655/0733-1347(2007)20[178:MAFCTT]2.0.CO;2

Placental Function In Lizards.

Publisher: Elsevier BV

Date: 12-2004

DOI: 10.1016/J.ICS.2004.08.055

Development of yolk sac and chorioallantoic membranes in the Lord Howe Island skink, Oligosoma lichenigerum

Publisher: Wiley

Date: 22-06-2012

DOI: 10.1002/JMOR.20052

Abstract: Development of the yolk sac of squamate reptiles (lizards and snakes) differs from other amniote lineages in the pattern of growth of extraembryonic mesoderm, which produces a cavity, the yolk cleft, within the yolk. The structure of the yolk cleft and the accompanying isolated yolk mass influence development of the allantois and chorioallantoic membrane. The yolk cleft of viviparous species of the Eugongylus group of scincid lizards is the foundation for an elaborate yolk sac placenta development of the yolk cleft of oviparous species has not been studied. We used light microscopy to describe the yolk sac and chorioallantoic membrane in a developmental series of an oviparous member of this species group, Oligosoma lichenigerum. Topology of the extraembryonic membranes of late stage embryos differs from viviparous species as a result of differences in development of the yolk sac. The chorioallantoic membrane encircles the egg of O. lichenigerum but is confined to the embryonic hemisphere of the egg in viviparous species. Early development of the yolk cleft is similar for both modes of parity, but in contrast to viviparous species, the yolk cleft of O. lichenigerum is transformed into a tube-like structure, which fills with cells. The yolk cleft originates as extraembryonic mesoderm is erted from the periphery of the egg into the yolk sac cavity. As a result, a bilaminar omphalopleure persists over the abembryonic surface of the yolk. The bilaminar omphalopleure is ultimately displaced by intrusion of allantoic mesoderm between ectodermal and endodermal layers. The resulting chorioallantoic membrane has a similar structure but different developmental history to the chorioallantoic membrane of the embryonic hemisphere of the egg.

Phylogeographic divergence in the widespread delicate skink (Lampropholis delicata) corresponds to dry habitat barriers in eastern Australia

Publisher: Springer Science and Business Media LLC

Date: 04-07-2011

DOI: 10.1186/1471-2148-11-191

HoxA10-like proteins in the reproductive tract of the viviparous lizard Eulamprus tympanum and the oviparous lizard Lampropholis guichenoti

Publisher: Elsevier BV

Date: 09-2005

DOI: 10.1016/J.CBPC.2005.07.001

Abstract: The gene HoxA10 and its protein product are essential for the formation of the extensions of the plasma membrane called uterodomes or pinopods in mammalian uterine epithelia. In mice, the presence of the HoxA10 protein and uterodomes is needed for uterine receptivity to blastocyst implantation. The viviparous lizard Eul rus tympanum displays uterodomes whereas the oviparous lizard L ropholis guichenoti does not. To explore the theory that HoxA10 is involved in the formation of uterodomes we investigated whether HoxA10 immunoreactive proteins were present in both species during their reproductive cycles. Oviduct proteins from vitellogenic, gravid or non-reproductive L. guichenoti (n=19) and E. tympanum (n=28) were separated by electrophoresis and analysed by Western blot and specific antibodies to HoxA10. E. tympanum displayed HoxA10 immunoreactive bands at 59 and 63 kDa in 20 out of the 28 s les. All of the L. guichenoti s les displayed HoxA10 immunoreactive bands, 18 had bands at 59 and 64 kDa and 1 animal had a single band at 59 kDa. There were no significant differences in the level of HoxA10 immunoreactivity between the different stages of reproductive cycle in either species. The different molecular mass of the larger band in L. guichenoti (64 kDa) compared to E. tympanum (63 kDa) indicates that the two lizards express different isoforms of the HoxA10-like proteins and it will be interesting in future studies to determine whether there are differences in the biological activity of the proteins that regulate different physiological functions in the uterus of viviparous and oviparous lizards.

Allelic expression of mammalian imprinted genes in a matrotrophic lizard, Pseudemoia entrecasteauxii

Publisher: Springer Science and Business Media LLC

Date: 03-2016

DOI: 10.1007/S00427-016-0531-X

Abstract: Genomic imprinting is a process that results in the differential expression of genes depending on their parent of origin. It occurs in both plants and live-bearing mammals, with imprinted genes typically regulating the ability of an embryo to manipulate the maternal provision of nutrients. Genomic imprinting increases the potential for selection to act separately on paternally and maternally expressed genes, which increases the number of opportunities that selection can facilitate embryonic control over maternal nutrient provision. By looking for imprinting in an independent matrotrophic lineage, the viviparous lizard Pseudemoia entrecasteauxii (Scincidae), we test the hypothesis that genomic imprinting facilitates the evolution of substantial placental nutrient transport to embryos (matrotrophy). We sequenced transcriptomes from the embryonic component of lizard placentae to determine whether there are parent-of-origin differences in expression of genes that are imprinted in mammals. Of these genes, 19 had sufficiently high expression in the lizard to identify polymorphisms in transcribed sequences. We identified bi-allelic expression in 17 genes (including insulin-like growth factor 2), indicating that neither allele was imprinted. These data suggest that either genomic imprinting has not evolved in this matrotrophic skink or, if it has, it has evolved in different genes to mammals. We outline how these hypotheses can be tested. This study highlights important differences between mammalian and reptile pregnancy and the absence of any shared imprinting genes reflects fundamental differences in the way that pregnancy has evolved in these two lineages.

Angiogenesis of the uterus and chorioallantois in the eastern water skink Eulamprus quoyii

Publisher: The Company of Biologists

Date: 10-2010

DOI: 10.1242/JEB.046862

Abstract: We have discovered a modification of the uterus that appears to facilitate maternal-fetal communication during pregnancy in the scincid lizard Eul rus quoyii. A vessel-dense elliptical area (VDE) on the mesometrial side of the uterus expands as the embryo grows, providing a large vascular area for physiological exchange between mother and embryo. The VDE is already developed in females with newly ovulated eggs, and is situated directly adjacent to the chorioallantois of the embryo when it develops. It is likely that signals from the early developing embryo determine the position of the VDE, as the VDE is off-centre in cases where the embryo sits obliquely in the uterus. The VDE is not a modification of the uterus over the entire chorioallantoic placenta, as the VDE is smaller than the chorioallantois after embryonic stage 33, but expansion of the VDE and growth of the chorioallantois during pregnancy are strongly correlated. The expansion of the VDE is also strongly correlated with embryonic growth and increasing embryonic oxygen demand (). We propose that angiogenic stimuli are exchanged between the VDE and the chorioallantois in E. quoyii, allowing the simultaneous growth of both tissues.

Is basking opportunity in the viviparous lizard, Eulamprus tympanum, compromised by the presence of a predator scent?

Publisher: Society for the Study of Amphibians and Reptiles

Date: 06-2007

DOI: 10.1670/0022-1511(2007)41[287:IBOITV]2.0.CO;2

The ecology and evolution of temperature‐dependent reaction norms for sex determination in reptiles: a mechanistic conceptual model

Publisher: Wiley

Date: 14-06-2016

DOI: 10.1111/BRV.12285

Abstract: Sex-determining mechanisms are broadly categorised as being based on either genetic or environmental factors. Vertebrate sex determination exhibits remarkable ersity but displays distinct phylogenetic patterns. While all eutherian mammals possess XY male heterogamety and female heterogamety (ZW) is ubiquitous in birds, poikilothermic vertebrates (fish, hibians and reptiles) exhibit multiple genetic sex-determination (GSD) systems as well as environmental sex determination (ESD). Temperature is the factor controlling ESD in reptiles and temperature-dependent sex determination (TSD) in reptiles has become a focal point in the study of this phenomenon. Current patterns of climate change may cause detrimental skews in the population sex ratios of reptiles exhibiting TSD. Understanding the patterns of variation, both within and among populations and linking such patterns with the selection processes they are associated with, is the central challenge of research aimed at predicting the capacity of populations to adapt to novel conditions. Here we present a conceptual model that innovates by defining an in idual reaction norm for sex determination as a range of incubation temperatures. By deconstructing in idual reaction norms for TSD and revealing their underlying interacting elements, we offer a conceptual solution that explains how variation among in idual reaction norms can be inferred from the pattern of population reaction norms. The model also links environmental variation with the different patterns of TSD and describes the processes from which they may arise. Specific climate scenarios are singled out as eco-evolutionary traps that may lead to demographic extinction or a transition to either male or female heterogametic GSD. We describe how the conceptual principles can be applied to interpret TSD data and to explain the adaptive capacity of TSD to climate change as well as its limits and the potential applications for conservation and management programs.

High Food Abundance Permits the Evolution of Placentotrophy: Evidence from a Placental Lizard,Pseudemoia entrecasteauxii

Publisher: University of Chicago Press

Date: 08-2014

DOI: 10.1086/677138

Abstract: Mechanisms of reproductive allocation are major determinants of fitness because embryos cannot complete development without receiving sufficient nutrition from their parents. The nourishment of offspring via placentas (placentotrophy) has evolved repeatedly in vertebrates, including multiple times in squamate reptiles (lizards and snakes). Placentotrophy has been suggested to evolve only if food is sufficiently abundant throughout gestation to allow successful embryogenesis. If scarcity of food prevents successful embryogenesis, females should recoup nutrients allocated to embryos via abortion, reabsorption, and/or cannibalism. We tested these hypotheses in the placentotrophic southern grass skink Pseudemoia entrecasteauxii. We fed females one of four diets (high constant, high variable, low constant, and low variable) during gestation and tested the effects of both food amount and schedule of feeding on developmental success, cannibalism rate, placental nutrient transport, offspring size, and maternal growth and body condition. Low food availability reduced developmental success, placental nutrient transport, offspring size, and maternal growth and body condition. Cannibalism of offspring also increased when food was scarce. Schedule of feeding did not affect offspring or mothers. We suggest that high food abundance and ability to abort and cannibalize poor-quality offspring are permissive factors necessary for placentotrophy to be a viable strategy of reproductive allocation.

Performance of Juvenile Tuatara Depends on Age, Clutch, and Incubation Regime

Publisher: Society for the Study of Amphibians and Reptiles

Date: 09-2006

DOI: 10.1670/0022-1511(2006)40[399:POJTDO]2.0.CO;2

Expression and localization of Ca(2+)-ATPase in the uterus during the reproductive cycle of king quail (Coturnix chinensis) and zebra finch (Poephila guttata)

Publisher: Elsevier BV

Date: 2008

DOI: 10.1016/J.CBPA.2007.09.014

Abstract: Calcium ATPase (Ca2+-ATPase) is a key enzyme that participates in the translocation of calcium in the uterus of oviparous amniotes during eggshell formation. We used Western blot and indirect immunofluorescence microscopy to determine expression and localisation of uterine Ca2+-ATPase during the reproductive cycle of king quail and zebra finch. The pattern of Ca2+-ATPase expression and localisation during the reproductive cycle was similar for both species. Immunoblots of uterine extracts from quail and finch indicated that Ca2+-ATPase expression is reduced in non-reproductive compared to reproductive females. Similarly, in non-reproductive females, weak apical immunofluorescent staining of Ca2+-ATPase is localised to epithelial cells in a small number of uterine tubular glands. A large increase in apical immunofluorescent staining of tubular gland epithelia occurs in both vitellogenic and reproductive females. The presence of Ca2+-ATPase on the apical surface of tubular gland epithelial cells suggests that the enzyme is involved in the translocation of calcium out of the tubular gland epithelia and into the concentrated fluid of the uterine lumen. Presence of Ca2+-ATPase in vitellogenic females indicates that the enzyme is expressed prior to the time of ovulation and eggshell calcification.

What factors allow opportunistic nocturnal activity in a primarily diurnal desert lizard (Ctenotus pantherinus)?

Publisher: Elsevier BV

Date: 06-2010

DOI: 10.1016/J.CBPA.2010.02.007

Abstract: Most animals show strong 24-h patterns of activity, usually being diurnal or nocturnal. An Australian desert skink, Ctenotus pantherinus, is unusual in being active day and night when all other Ctenotus species are diurnal, making it an excellent model to explore factors that promote night-time activity. We tested whether C. pantherinus 1) selects cooler temperatures than diurnal skinks, 2) shows no difference in mean selected temperature between day and night, 3) has the same metabolic rate during the day and night, 4) selects termites over other prey types, 5) can detect prey using only auditory or olfactory senses, and 6) experiences lower predation risk at night than during the day. C.pantherinus shows many features of diurnal skink species, with a high mean selected temperature (36.1+/-1.6 degrees C) that is the same night and day, and a 32% lower metabolic rate at night than during the day. C.pantherinus selects termite prey over other insects and can detect prey using only auditory and olfactory senses models of C. pantherinus experienced less predation at night than during the day. Preference for termites and reduced predation risk at night favour opportunistic nocturnal activity in this predominantly diurnal lizard and may contribute to its wide geographic distribution in arid Australia.

Keratinization and ultrastructure of the epidermis of late embryonic stages in the alligator (Alligator mississippiensis)

Publisher: Wiley

Date: 07-2002

DOI: 10.1046/J.1469-7580.2002.00075.X

Abstract: Using specific anti-beta keratin and general anti-alpha keratin antibodies, keratins were located in the epidermis of the alligator during the final developmental stages by ultrastructural and immunocytochemical methods. The maturation of the bilayered periderm (= embryonic epidermis) coincides with the disappearance of cell organelles, including the 25-35-nm-thick coarse filaments, and the coalescing of alpha-keratin filaments into a compact mass. The plasmalemma of peridermal cells forms a 15-25-nm-thick electron-dense corneous envelope. These changes start at stage 25, about 3 weeks before hatching, and continue until hatching when the embryonic epidermis is shed. Immature beta-keratogenic cells beneath the embryonic epidermis accumulate immunolabelled beta-filaments which are packed into thin, electron-pale beta-keratogenic cells in the corneous layer. Together, electron-pale and electron-dense materials form a compact 3-4-nm filament pattern of beta-keratin. Melanosomes from epidermal melanocytes, incorporated into beta-cells, give rise to the banded skin pattern of hatchlings. Beta-keratin production is much reduced in the hinge regions, where many alpha-filaments remain packed together with lipid droplets or mucous granules into thinner, more electron-dense, alpha-cells. The keratinaceous material of the alpha-cells is mostly concentrated along the cell membrane, while the lipid/mucous material remains centrally located, as in sebokeratinocytes of the apteric areas of avian skin. Some lipid and mucus is also incorporated into typical beta-cells of the outer scale surface, so that lipids are part of the fully keratinized hard keratin layer of the alligator. Lipids within beta-cells of outer scale surfaces and alpha-cells of the hinge region are probably responsible for limiting water loss and ion movements across the skin. Neither typical mammalian keratohyalin granules nor lepidosaurian keratohyalin-like granules were detected anywhere in alligator epidermis. The combination of anti-beta and anti-alpha keratin antibodies revealed different distributions of beta- and alpha-keratins. In late embryonic stages (25-26 to hatching), beta-keratin occurs only in the upper suprabasal cells, in prekeratinized and keratinized layers, whereas alpha-keratin bundles (tonofilaments) remain only in the lowest layers. The cross-reactivity of the beta-antibody, produced against a chick scale keratin, further shows that avian and crocodilian hard (beta) keratins share common antigenic sites, reflecting a phylogenetic affinity between these taxa.

Desmoglein-2 during pregnancy and its role in the evolution of viviparity in a marsupial (Sminthopsis crassicaudata; Dasyuridae)

Publisher: Wiley

Date: 20-10-2015

DOI: 10.1002/JMOR.20333

Abstract: Attachment of the blastocyst and formation of the placenta during pregnancy is dependent on structural and cellular changes occurring in the uterine epithelium and in particular to the plasma membrane of these uterine cells. Desmosome expression decreases during pregnancy in eutherians and some squamates, presumably allowing for remodeling of the uterine epithelium and invasion of the trophoblast during implantation. Marsupials are a distinct mammalian amniote lineage of viviparity, with a short implantation or attachment period and varying levels of invasive placentation. To test the generality of changes to the uterine epithelium during pregnancy across mammals, we characterized the distribution of desmosomes in the uterine epithelial cells of a marsupial, Sminthopsis crassicaudata, using electron microscopy and immunohistochemistry. The absolute number of desmosomes along the lateral plasma membrane decreases during pregnancy and desmosomes are redistributed towards the apical region of the lateral plasma membrane as pregnancy proceeds, similar to what occurs during pregnancy in eutherian mammals. Despite the lower level of maternal investment in pregnancy and the noninvasive structure of fetal membranes in marsupials there are similarities in number and redistribution of desmosomes along the plasma membrane and changes to the morphology of the uterine epithelial cells suggesting that similar plasma membrane changes occur across all lineages of amniote vertebrates.

Comparative genomics of hormonal signaling in the chorioallantoic membrane of oviparous and viviparous amniotes

Publisher: Elsevier BV

Date: 04-2017

DOI: 10.1016/J.YGCEN.2016.04.017

Abstract: In oviparous amniotes (reptiles, birds, and mammals) the chorioallantoic membrane (CAM) lines the inside of the egg and acts as the living point of contact between the embryo and the outside world. In livebearing (viviparous) amniotes, communication during embryonic development occurs across placental tissues, which form between the uterine tissue of the mother and the CAM of the embryo. In both oviparous and viviparous taxa, the CAM is at the interface of the embryo and the external environment and can transfer signals from there to the embryo proper. To understand the evolution of placental hormone production in amniotes, we examined the expression of genes involved in hormone synthesis, metabolism, and hormone receptivity in the CAM of species across the amniote phylogeny. We collected transcriptome data for the chorioallantoic membranes of the chicken (oviparous), the lizards Lerista bougainvillii (both oviparous and viviparous populations) and Pseudemoia entrecasteauxii (viviparous), and the horse Equus caballus (viviparous). The viviparous taxa differ in their mechanisms of nutrient provisioning: L. bougainvillii is lecithotrophic (embryonic nourishment is provided via the yolk only), but P. entrecasteauxii and the horse are placentotrophic (embryos are nourished via placental transport). Of the 423 hormone-related genes that we examined, 91 genes are expressed in all studied species, suggesting that the chorioallantoic membrane ancestrally had an endocrine function. Therefore, the chorioallantoic membrane appears to be a highly hormonally active organ in all amniotes. No genes are expressed only in viviparous species, suggesting that the evolution of viviparity has not required the recruitment of any specific hormone-related genes. Our data suggest that the endocrine function of the CAM as a placental tissue evolved in part through co-option of ancestral gene expression patterns.

Distribution of lipids from the yolk to the tissues during development of the water python ( Liasis fuscus )

Publisher: Springer Science and Business Media LLC

Date: 09-2003

DOI: 10.1007/S00360-003-0362-8

Abstract: Energy metabolism during embryonic development of snakes differs in several respects from the patterns displayed by other reptiles. There are, however, no previous reports describing the main energy source for development, the yolk lipids, in snake eggs. There is also no information on the distribution of yolk fatty acids to the tissues during snake development. In eggs of the water python ( Liasis fuscus), we report that triacylglycerol, phospholipid, cholesteryl ester and free cholesterol, respectively, form 70.3%, 14.1%, 5.7% and 2.1% of the total lipid. The main polyunsaturate of the yolk lipid classes is 18:2n-6. The yolk phospholipid contains 20:4n-6 and 22:6n-3 at 13.0% and 3.6% (w/w), respectively. Approximately 10% and 30% of the initial egg lipids are respectively recovered in the residual yolk and the fat body of the hatchling. A major function of yolk lipid is, therefore, to provision the neonate with large energy reserves. The proportion of 22:6n-3 in brain phospholipid of the hatchling is 11.1% (w/w): this represents only 0.24% of the amount of 22:6n-3 originally present in the egg. This also contrasts with values for free-living avian species where the proportion of DHA in neonatal brain phospholipid is 16-19%. In the liver of the newly hatched python, triacylglycerol, phospholipid and cholesteryl ester, respectively, form 68.2%, 7.7% and 14.3% of total lipid. This contrasts with embryos of birds where cholesteryl ester forms up to 80% of total liver lipid and suggests that the mechanism of lipid transfer in the water python embryo differs in some respects from the avian situation.

Evolution of viviparity: what can Australian lizards tell us?

Publisher: Elsevier BV

Date: 04-2002

DOI: 10.1016/S1096-4959(02)00013-1

Abstract: Historically, Australia has been important in the study of, and the development of hypotheses aimed at understanding, the evolution of viviparity in amniote vertebrates. Part of the importance of Australia in the field results from a rich fauna of skinks, including one of the broadest ranges of ersity of placental structures within one geographic region. During the last decade, we have focussed our studies on one lineage, the Eugongylus group of skinks of the subfamily Lygosominae because it contains oviparous species and some that exhibit complex placentae. Our specific objective has been to attempt to understand the fundamental steps required when viviparity, and ultimately complex placentae, evolve from oviparous ancestors. We have taken a three-prong approach: (1) detailed study of the morphology and ontogeny of the placentae of key species at the light microscope level (2) study of changes in the uterus associated with pregnancy, or the plasma membrane transformation and (3) measures of the net exchange of nutrients across the placenta or eggshell of key species. In turn, we have found that: (1) details of the morphology and ontogeny of placentae are more complex that originally envisaged, and that the early conclusions about a sequence in the evolution of complex placentae was naïve (2) a plasma membrane transformation occurs in viviparous, but not oviparous lizards, and thus may be a fundamental feature of the evolution of viviparity in amniotes and (3) species with more complex chorioallantoic placentae tend to transport more nutrients across the placenta during pregnancy than those with simpler chorioallantoic placentae but, because the correlation is not tight, the importance of the omphaloplacenta in transporting nutrients may have been overlooked. Also, the composition of yolk of highly matrotrophic species is broadly similar, but not identical, to the yolk of oviparous species. Some of the interpretation of our data within the context of our specific objective is not yet possible, pending the publication of a robust phylogeny of Eugongylus group skinks. Once such a phylogeny is available, we are in a position to propose specific hypotheses about the evolution of viviparity that can be tested using another lineage of amniotes, possibly Mabuya group skinks.

Fundamentals of viviparity: Comparison of seasonal changes in the uterine epithelium of oviparous and viviparous Lerista bougainvillii (Squamata : Scincidae)

Publisher: Wiley

Date: 2007

DOI: 10.1002/JMOR.10522

Abstract: Distinct differences in epithelial response between oviparous and viviparous species of skinks led us to investigate morphological differences in the uterus of a species that exhibits bi-modal reproduction and that may indicate specialities for the different requirements of viviparity and oviparity. The uteri of females from oviparous and viviparous populations of the Australian scincid lizard, Lerista bougainvillii, are described in detail to determine whether the occurrence of uterodomes and the plasma membrane transformation, found in other viviparous species but not oviparous species, are indeed features characteristic of viviparity. Oviductal tissue was dissected at three different stages of reproduction from lizards from both populations: 1) vitellogenic, 2) gravid or pregnant, and 3) non-reproductive or quiescent. Tissue was observed using both scanning and transmission electron microscopy. Lerista bougainvillii has a simple placental morphology with simple squamous epithelium. In contrast to mammals and other viviparous skinks, L. bougainvillii does not undergo a plasma membrane transformation, but early signs of placentation in viviparous in iduals are indicated by changes in the uterine surface that occur largely after embryonic stage 30. There are no obvious cellular differences between the uteri of oviparous and viviparous L. bougainvillii at the non-reproductive and vitellogenic phase of the reproductive cycle but throughout gestation/gravidity, the cellular differences that could be related to the changing functional requirements with the retention of the viviparous embryo, became apparent. A plasma membrane transformation with ensuing uterodome formation does not occur, which suggests that these more sophisticated changes are a feature of advanced placental development in reptiles.

A note on pterosaur nesting behavior

Publisher: Informa UK Limited

Date: 12-2007

DOI: 10.1080/08912960701189800

Uterine epithelial changes during placentation in the viviparous skink Eulamprus tympanum

Publisher: Wiley

Date: 2007

DOI: 10.1002/JMOR.10520

Abstract: We used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to describe the complete ontogeny of simple placentation and the development of both the yolk sac placentae and chorioallantoic placentae from nonreproductive through postparturition phases in the maternal uterine epithelium of the Australian skink, Eul rus tympanum. We chose E. tympanum, a species with a simple, noninvasive placenta, and which we know, has little net nutrient uptake during gestation to develop hypotheses about placental function and to identify any difference between the oviparous and viviparous conditions. Placental differentiation into the chorioallantoic placenta and yolk sac placenta occurs from embryonic Stage 29 both placentae are simple structures without specialized features for materno/fetal connection. The uterine epithelial cells are not squamous as previously described by Claire Weekes, but are columnar, becoming increasingly attenuated because of the pressure of the impinging underlying capillaries as gestation progresses. When the females are nonreproductive, the luminal uterine surface is flat and the microvillous cells that contain electron-dense vesicles partly obscure the ciliated cells. As vitellogenesis progresses, the microvillous cells are less hypertrophied than in nonreproductive females. After ovulation and fertilization, there is no regional differentiation of the uterine epithelium around the circumference of the egg. The first differentiation, associated with the chorioallantoic placentae and yolk sac placentae, occurs at embryonic Stage 29 and continues through to Stage 39. As gestation proceeds, the uterine chorioallantoic placenta forms ridges, the microvillous cells become less hypertrophied, ciliated cells are less abundant, the underlying blood vessels increase in size, and the gland openings at the uterine surface are more apparent. In contrast, the yolk sac placenta has no particular folding with cells having a random orientation and where the microvillous cells remain hypertrophied throughout gestation. However, the ciliated cells become less abundant as gestation proceeds, as also seen in the chorioallantoic placenta. Secretory vesicles are visible in the uterine lumen. All placental differentiation and cell detail is lost at Stage 40, and the uterine structure has returned to the nonreproductive condition within 2 weeks. Circulating progesterone concentrations begin to rise during late vitellogenesis, peak at embryonic Stages 28-30, and decline after Stage 35 in the later stages of gestation. The coincidence between the time of oviposition and placental differentiation demonstrates a similarity during gestation in the uterus between oviparous and simple placental viviparous squamates.

Does foraging mode affect metabolic responses to feeding? A study of pygopodid lizards

Publisher: Oxford University Press (OUP)

Date: 10-2013

DOI: 10.1093/CZOOLO/59.5.618

Abstract: Foraging mode (ambush vs. active) profoundly affects many aspects of organismal biology, including metabolic rates and their relationship with food intake. Previous studies on snakes suggest that ambushers tend to have lower standard metabolic rates (SMR) and higher energetic costs of digestion and assimilation of prey (specific dynamic action, or SDA) than do active foragers. However, phylogenetic considerations may be at least partly responsible for such patterns, as foraging mode is strongly conserved evolutionarily and most SDA studies have focused on species from only two lineages of ambush foragers (pythonid and viperid snakes) and one lineage of active foragers (colubrid snakes). We sought to deconfound the effects of phylogeny and foraging mode, investigating SMR and SDA in two closely related pygopodid lizards, the common scaly-foot Pygopus lepidopodus (active forager) and Burton’s legless lizard Lialis burtonis (ambush forager). Consistent with the pattern seen in snakes, L. burtonis exhibits a significantly lower SMR and a higher SDA than does P. lepidopodus. The magnitude of SDA in L. burtonis is comparable to that of some pythons and vipers, providing yet more evidence for the remarkable convergence between this species and ambush-foraging snakes.

Uterine remodelling during pregnancy and pseudopregnancy in the brushtail possum (Trichosurus vulpecula; Phalangeridae)

Publisher: Wiley

Date: 11-04-2017

DOI: 10.1111/JOA.12610

Uterine Epithelial Cell Changes During Pregnancy in a Marsupial (Sminthopsis crassicaudata; Dasyuridae)

Publisher: Wiley

Date: 16-04-2014

DOI: 10.1002/JMOR.20282

Abstract: Formation of a placenta requires intimate contact between the embryonic and maternal uterine epithelia in early pregnancy. Contact is accompanied by a characteristic suite of changes to the plasma membranes of uterine epithelial cells, termed the plasma membrane transformation. The plasma membrane transformation occurs in eutherian mammals and in viviparous (live-bearing) squamate reptiles, and may be fundamental to the evolution of viviparity in amniotes. Marsupials provide an excellent opportunity to test the generality of this phenomenon. Here, we present the first detailed study of the plasma membrane transformation in a marsupial. We combine electron microscopy and immunohistochemistry to describe morphological and molecular features of uterine epithelial cells during pregnancy in the fat-tailed dunnart (Sminthopsis crassicaudata Dasyuridae). Cell morphology changes dramatically in S. crassicaudata during pregnancy. Apical microvilli are replaced by irregular blunt projections, then by spiky projections postimplantation. Cell surfaces flatten and ciliated cells are lost. Junctional complexes between adjacent cells increase in depth, then decrease just before implantation, which is consistent with junctional protein localization in this region of the cell membrane. The uterine cellular changes in S. crassicaudata are consistent with a plasma membrane transformation, and support the idea that this phenomenon is fundamental to the evolution of viviparity in amniote vertebrates.

Repeatability and correlation of physiological traits:

Publisher: Wiley

Date: 22-12-2017

DOI: 10.1002/ECE3.2632

University Of Sydney

Location: Australia

View Organisation

Linkage Projects - Grant ID: LP0668879

Start Date: 07-2006

End Date: 08-2010

Amount: $259,340.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP140100011

Start Date: 11-2014

End Date: 12-2019

Amount: $435,280.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0349110

Start Date: 09-2003

End Date: 12-2006

Amount: $72,099.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0343428

Start Date: 2003

End Date: 12-2005

Amount: $330,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0878619

Start Date: 05-2008

End Date: 12-2011

Amount: $360,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP130101589

Start Date: 2013

End Date: 06-2016

Amount: $310,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0557526

Start Date: 05-2005

End Date: 05-2010

Amount: $520,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP120100649

Start Date: 04-2012

End Date: 08-2015

Amount: $550,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0883055

Start Date: 02-2008

End Date: 10-2008

Amount: $170,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP200200884

Start Date: 05-2022

End Date: 05-2026

Amount: $601,024.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP180103370

Start Date: 2018

End Date: 12-2022

Amount: $572,496.00

Funder: Australian Research Council