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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Ethology and Sociobiology | Ecology | Behavioural Ecology | Zoology | Animal Behaviour | Animal Neurobiology |
Expanding Knowledge in the Biological Sciences | Flora, Fauna and Biodiversity at Regional or Larger Scales | Expanding Knowledge in the Environmental Sciences | Expanding Knowledge in Psychology and Cognitive Sciences
Publisher: Wiley
Date: 19-05-2007
Publisher: Springer Science and Business Media LLC
Date: 27-10-2010
DOI: 10.1038/NATURE09512
Abstract: Sex determination is a fundamental biological process, yet its mechanisms are remarkably erse. In vertebrates, sex can be determined by inherited genetic factors or by the temperature experienced during embryonic development. However, the evolutionary causes of this ersity remain unknown. Here we show that live-bearing lizards at different climatic extremes of the species' distribution differ in their sex-determining mechanisms, with temperature-dependent sex determination in lowlands and genotypic sex determination in highlands. A theoretical model parameterized with field data accurately predicts this ergence in sex-determining systems and the consequence thereof for variation in cohort sex ratios among years. Furthermore, we show that ergent natural selection on sex determination across altitudes is caused by climatic effects on lizard life history and variation in the magnitude of between-year temperature fluctuations. Our results establish an adaptive explanation for intra-specific ergence in sex-determining systems driven by phenotypic plasticity and ecological selection, thereby providing a unifying framework for integrating the developmental, ecological and evolutionary basis for variation in vertebrate sex determination.
Publisher: Oxford University Press (OUP)
Date: 25-04-2019
Publisher: Springer Science and Business Media LLC
Date: 08-05-2018
DOI: 10.1007/S00442-018-4153-Z
Abstract: Social learning is thought to be advantageous as it allows an animal to gather information quickly without engaging in costly trial-and-error learning. However, animals should be selective about when and whom they learn from. Familiarity is predicted to positively influence an animal's reliance on social learning yet, few studies have empirically tested this theory. We used a lizard (Liopholis whitii) that forms long-term monogamous pair bonds to examine the effects of partner familiarity on social learning in two novel foraging tasks, an association and a reversal task. We allowed female lizards to observe trained conspecifics that were either familiar (social mate) or unfamiliar execute these tasks and compared these two groups with control females that did not receive social information. Lizards preferentially relied on trial-and-error learning in the association task. In the reversal task, lizards that were demonstrated by familiar partners learnt in fewer trials compared to control lizards and made more correct choices. Our results provide some evidence for context-dependent learning with lizards differentiating between when they utilize social learning, and, to a limited degree, whom they learnt from. Understanding the role of the social context in which learning occurs provides important insights into the benefits of social learning and sociality more generally.
Publisher: The Royal Society
Date: 26-05-2021
Abstract: Emerging patterns suggest telomere dynamics and life history are fundamentally linked in endotherms through life-history traits that mediate the processes underlying telomere attrition. Unlike endotherms, ectotherms maintain the ability to lengthen somatic telomeres throughout life and the link between life-history strategies and ectotherm telomere dynamics is unknown. In a well-characterized model system ( Niveoscincus ocellatus ), we used long-term longitudinal data to study telomere dynamics across climatically ergent populations. We found longer telomeres in in iduals from the cool highlands than those from the warm lowlands at birth and as adults. The key determinant of adult telomere length across populations was telomere length at birth, with population-specific effects of age and growth on adult telomere length. The reproductive effort had no proximate effect on telomere length in either population. Maternal factors influenced telomere length at birth in the warm lowlands but not the cool highlands. Our results demonstrate that life-history traits can have pervasive and context-dependent effects on telomere dynamics in ectotherms both within and between populations. We argue that these telomere dynamics may reflect the populations' different life histories, with the slow-growing cool highland population investing more into telomere lengthening compared to the earlier-maturing warm lowland population.
Publisher: Springer Science and Business Media LLC
Date: 12-01-2021
Publisher: Wiley
Date: 23-06-2019
DOI: 10.1111/ACV.12519
Publisher: CSIRO Publishing
Date: 03-02-2022
DOI: 10.1071/ZO21023
Abstract: Sex is a pervasive factor that underpins functional phenotypic variation across a range of traits. Although sex can usually be distinguished morphologically, in some species this is not possible. The development of genetic markers for sex identification is, thus, key if we are to incorporate sex into an understanding of ecological or evolutionary process. Here we develop genetic markers for the identification of sex within an iconic Australian lizard group, the Egernia group, which is notable for its complex social behaviour. We used restriction-site associated DNA sequencing to characterise sex-specific genetic sequences for a key member of the group, Liopholis whitii, and designed primers for four of these putative sex-specific sequences. These primers lified across some, but not all, species of the group. Our results provided several important insights. They suggest conservatism of a XX/XY sex determination system within the group as well as sex-specific genomic regions that appear independent of the conserved genomic regions identified in other skink species. More broadly, the development of sex markers for the Egernia group opens up a range of potential research questions related to the role that sex plays in the mediation of social behaviour and, through this, the emergence and stability of social life.
Publisher: Wiley
Date: 04-2018
DOI: 10.1002/JEZ.2181
Abstract: Early life environments shape phenotypic development in important ways that can lead to long-lasting effects on phenotype and fitness. In reptiles, one aspect of the early environment that impacts development is temperature (termed 'thermal developmental plasticity'). Indeed, the thermal environment during incubation is known to influence morphological, physiological, and behavioral traits, some of which have important consequences for many ecological and evolutionary processes. Despite this, few studies have attempted to synthesize and collate data from this expansive and important body of research. Here, we systematically review research into thermal developmental plasticity across reptiles, structured around the key papers and findings that have shaped the field over the past 50 years. From these papers, we introduce a large database (the 'Reptile Development Database') consisting of 9,773 trait means across 300 studies examining thermal developmental plasticity. This dataset encompasses data on a range of phenotypes, including morphological, physiological, behavioral, and performance traits along with growth rate, incubation duration, sex ratio, and survival (e.g., hatching success) across all major reptile clades. Finally, from our literature synthesis and data exploration, we identify key research themes associated with thermal developmental plasticity, important gaps in empirical research, and demonstrate how future progress can be made through targeted empirical, meta-analytic, and comparative work.
Publisher: Elsevier BV
Date: 07-2020
Publisher: Springer Science and Business Media LLC
Date: 06-10-2016
Publisher: Elsevier BV
Date: 10-2017
Publisher: Wiley
Date: 26-07-2021
DOI: 10.1111/BRV.12784
Abstract: Animal sociality plays a crucial organisational role in evolution. As a result, understanding the factors that promote the emergence, maintenance, and ersification of animal societies is of great interest to biologists. Climate is among the foremost ecological factors implicated in evolutionary transitions in social organisation, but we are only beginning to unravel the possible mechanisms and specific climatic variables that underlie these associations. Ambient temperature is a key abiotic factor shaping the spatio‐temporal distribution of in iduals and has a particularly strong influence on behaviour. Whether such effects play a broader role in social evolution remains to be seen. In this review, we develop a conceptual framework for understanding how thermal effects integrate into pathways that mediate the opportunities, nature, and context of social interactions. We then implement this framework to discuss the capacity for temperature to initiate organisational changes across three broad categories of social evolution: group formation, group maintenance, and group elaboration. For each category, we focus on pivotal traits likely to have underpinned key social transitions and explore the potential for temperature to affect changes in these traits by leveraging empirical ex les from the literature on thermal and behavioural ecology. Finally, we discuss research directions that should be prioritised to understand the potentially constructive and/or destructive effects of future warming on the origins, maintenance, and ersification of animal societies.
Publisher: The Royal Society
Date: 05-2017
Abstract: The extent to which key biological processes, such as sex determination, respond to environmental fluctuations is fundamental for assessing species' susceptibility to ongoing climate change. Few studies, however, address how climate affects offspring sex in the wild. We monitored two climatically distinct populations of the viviparous skink Niveoscincus ocellatus for 16 years, recording environmental temperatures, offspring sex and date of birth. We found strong population-specific effects of temperature on offspring sex, with female offspring more common in warm years at the lowland site but no effect at the highland site. In contrast, date of birth advanced similarly in response to temperature at both sites. These results suggest strong population-specific effects of temperature on offspring sex that are independent of climatic effects on other physiological processes. These results have significant implications for our understanding of the ecological and evolutionary consequences of variation in sex ratios under climate change.
Publisher: Public Library of Science (PLoS)
Date: 23-04-2015
Publisher: The Royal Society
Date: 06-2022
Abstract: Evolutionary transitions in sex-determining systems have occurred frequently yet understanding how they occur remains a major challenge. In reptiles, transitions from genetic to temperature-dependent sex determination can occur if the gene products that determine sex evolve thermal sensitivity, resulting in sex-reversed in iduals. However, evidence of sex reversal is limited to oviparous reptiles. Here we used thermal experiments to test whether sex reversal is responsible for differences in sex determination in a viviparous reptile, Carinascincus ocellatus, a species with XY sex chromosomes and population-specific sex ratio response to temperature. We show that sex reversal is occurring and that its frequency is related to temperature. Sex reversal was unidirectional (phenotypic males with XX genotype) and observed in both high- and low-elevation populations. We propose that XX-biased genotypic sex ratios could produce either male- or female-biased phenotypic sex ratios as observed in low-elevation C. ocellatus under variable rates of XX sex reversal. We discuss reasons why sex reversal may not influence sex ratios at high elevation. Our results suggest that the mechanism responsible for evolutionary transitions from genotypic to temperature-dependent sex determination is more complex than can be explained by a single process such as sex reversal.
Publisher: Brill
Date: 2009
Publisher: Oxford University Press (OUP)
Date: 19-09-2016
Publisher: Oxford University Press (OUP)
Date: 2009
Publisher: Wiley
Date: 13-09-2017
DOI: 10.1111/EVO.13317
Abstract: Divergence in communication systems should influence the likelihood that in iduals from different lineages interbreed, and consequently shape the direction and rate of hybridization. Here, we studied the role of chemical communication in hybridization, and its contribution to asymmetric and sexually selected introgression between two lineages of the common wall lizard (Podarcis muralis). Males of the two lineages differed in the chemical composition of their femoral secretions. Chemical profiles provided information regarding male secondary sexual characters, but the associations were variable and inconsistent between lineages. In experimental contact zones, chemical composition was weakly associated with male reproductive success, and did not predict the likelihood of hybridization. Consistent with these results, introgression of chemical profiles in a natural hybrid zone resembled that of neutral nuclear genetic markers overall, but one compound in particular (tocopherol methyl ether) matched closely the introgression of visual sexual characters. These results imply that associations among male chemical profiles, sexual characters, and reproductive success largely reflect transient and environmentally driven effects, and that genetic ergence in chemical composition is largely neutral. We therefore suggest that femoral secretions in wall lizards primarily provide information about residency and in idual identity rather than function as sexual signals.
Publisher: The Royal Society
Date: 07-2019
Abstract: Large-scale tissue regeneration has potential consequences for telomere length through increases in cell ision and changes in metabolism which increase the potential for oxidative stress damage to telomeres. The effects of regeneration on telomere dynamics have been studied in fish and marine invertebrates, but the literature is scarce for terrestrial species. We experimentally induced tail autotomy in a lizard ( Niveoscincus ocellatus ) and assessed relative telomere length (RTL) in blood s les before and after partial tail regeneration while concurrently measuring reactive oxygen species (ROS) levels. The change in ROS levels was a significant explanatory variable for the change in RTL over the 60-day experiment. At the average value of ROS change, the mean RTL increased significantly in the control group (intact tails), but there was no such evidence in the regenerating group. By contrast, ROS levels decreased significantly in the regenerating group, but there was no such evidence in the control group. Combined, these results suggest that tail regeneration following autotomy involves a response to oxidative stress and this potentially comes at a cost to telomere repair. This change in telomere maintenance demonstrates a potential long-term cost of tail regeneration beyond the regrowth of tissue itself.
Publisher: Springer Science and Business Media LLC
Date: 14-06-2017
DOI: 10.1038/S41598-017-03531-0
Abstract: The evolution of family living is underpinned by conflict and cooperation between family members. While family groups can be maintained by reducing conflict between parents and offspring, interactions between siblings may play an equally important role. Here, we compared the level of aggressive interactions between siblings to that between parents and their offspring in the family living skink Liopholis whitii . Aggressive interactions occurred much more frequently between siblings and between fathers and offspring than between mothers and their offspring. These results suggest that ecological and social conditions that reduce conflict between siblings and between males and offspring will be fundamental in the evolutionary maintenance and ersification of family living in these lizards.
Publisher: Wiley
Date: 25-01-2010
DOI: 10.1111/J.1420-9101.2009.01924.X
Abstract: The timing of birth is often correlated with offspring fitness in animals, but experimental studies that disentangle direct effects of parturition date and indirect effects mediated via variation in female traits are rare. In viviparous ectotherms, parturition date is largely driven by female thermal conditions, particularly maternal basking strategies. Our field and laboratory studies of a viviparous lizard (Niveoscincus ocellatus) show that earlier-born offspring are more likely to survive through their first winter and are larger following that winter, than are later-born conspecifics. Thus, the association between parturition date and offspring fitness is causal, rather than reflecting an underlying correlation between parturition date and maternal attributes. Survival selection on offspring confers a significant advantage for increased maternal basking in this species, mediated through fitness advantages of earlier parturition. We discuss the roles of environmentally imposed constraints and parent-offspring conflict in the evolution of maternal effects on parturition date.
Publisher: Springer Science and Business Media LLC
Date: 11-11-2010
Publisher: Wiley
Date: 10-09-2018
Abstract: Phenotypic variation provides the framework for natural selection to work upon, enabling adaptive evolution. One of the most discernible manifestations of phenotypic variability is colour variation. When this variation is discrete, genetically based colour pattern morphs occur simultaneously within a population. Why and how colour polymorphisms are maintained is an evolutionary puzzle. Several evolutionary drivers have been hypothesized as influencing clinal patterns of morph frequency, with spatial variation in climate and predation being considered especially important. Despite this, no study has examined both of their roles simultaneously. The aims of this study were to: (a) examine the covariation of physiology, environmental variables and colouration at a local scale and (b) determine if these factors and their interplay explain broad clinal variation in morph frequency. We used the lizard Liopholis whitii as a model system, as this species displays a discrete, heritable polymorphism for colour pattern (plain-backed, patterned morphs) whose morph frequency varies latitudinally. We measured reflectance, field activity temperatures and microhabitat structure to test for differences in crypsis, thermal biology and microhabitat selection of patterned and plain-backed morphs within a single population where colour morphs occur sympatrically. We then used data from the literature to perform a broad-scale analysis to identify whether these factors also explained the latitudinal variation of morph frequency in this species. At the local scale, plain-backed morphs were found to be less cryptic than patterned morphs while no other differences were detected in terms of thermal biology, dorsal reflectance and microhabitat use. At a broader scale, predation was the most influential factor mediating morph frequency across latitudes. However, the observed pattern of morph frequency is opposite to what the modelling results suggest in that the incidence of the least cryptic morph is highest where predation pressure is most severe. Clinal variation in the level of background matching between morphs or the potential reproductive advantage by the plain-backed morph may, instead, be driving the observed morph frequency. Together, these results provide key insights into the evolution of local adaptation as well as the ecological forces involved in driving the dynamics of colour polymorphism.
Publisher: Wiley
Date: 11-10-2023
Publisher: Cold Spring Harbor Laboratory
Date: 08-02-2021
DOI: 10.1101/2021.02.07.430163
Abstract: Live birth is a key innovation that has evolved from egg laying ancestors over 100 times in reptiles. However, egg-laying lizards and snakes often possess preferred body temperatures that are lethal to developing embryos, which should select against egg retention. Here, we demonstrate that thermal mismatches between mothers and offspring are widespread across the squamate phylogeny. This mismatch is resolved by gravid females adjusting their body temperature towards the thermal optimum of embryos. Importantly, phylogenetic reconstructions suggest this thermoregulatory behaviour evolved in egg-laying species prior to the evolution of live birth. Maternal thermoregulatory behaviour therefore bypasses the constraints imposed by a slowly evolving thermal physiology and has likely been a key facilitator in the repeated transitions to live birth.
Publisher: Elsevier BV
Date: 09-2019
DOI: 10.1016/J.CUB.2019.07.080
Abstract: Many ectotherms behaviourally thermoregulate to maintain their body temperatures within an optimal range. A new study suggests that turtle embryos developing inside eggs also have this capacity, and that this can have significant implications for sex determination.
Publisher: Wiley
Date: 19-08-2020
DOI: 10.1002/ECY.3136
Publisher: Springer Science and Business Media LLC
Date: 10-10-2012
Publisher: Wiley
Date: 04-2018
DOI: 10.1002/JEZ.2167
Abstract: Populations at the climatic margins of a species' distribution can be exposed to conditions that cause developmental stress, resulting in developmental abnormalities. Even within the thermal range of normal development, phenotypes often vary with developmental temperature (i.e., thermal phenotypic plasticity). These effects can have significant consequences for organismal fitness and, thus, population persistence. Reptiles, as ectotherms, are particularly vulnerable to thermal effects on development and are, therefore, considered to be at comparatively high risk from changing climates. Understanding the extent and direction of thermal effects on phenotypes and their fitness consequences is crucial if we are to make meaningful predictions of how populations and species will respond as climates warm. Here, we experimentally manipulated the thermal conditions experienced by females from a high-altitude, cold-adapted population of the viviparous skink, Niveoscincus ocellatus, to examine the consequences of thermal conditions at the margins of this population's normal temperature range. We found strong effects of thermal conditions on the development of key phenotypic traits that have implications for fitness. Specifically, we found that offspring born earlier as a result of high temperatures during gestation had increased growth over the first winter of life, but there was no effect on offspring survival, nor was there an effect of developmental temperature on the incidence of developmental abnormalities. Combined, our results suggest that advancing birth dates that result from warming climates may have positive effects in this population via increased growth.
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.JTHERBIO.2015.05.002
Abstract: Climatic changes are predicted to be greater in higher latitude and mountainous regions but species specific impacts are difficult to predict. This is partly due to inter-specific variance in the physiological traits which mediate environmental temperature effects at the organismal level. We examined variation in the critical thermal minimum (CTmin), critical thermal maximum (CTmax) and evaporative water loss rates (EWL) of a widespread lowland (Niveoscincus ocellatus) and two range restricted highland (N. microlepidotus and N. greeni) members of a cool temperate Tasmanian lizard genus. The widespread lowland species had significantly higher CTmin and CTmax and significantly lower EWL than both highland species. Implications of inter-specific variation in thermal tolerance for activity were examined under contemporary and future climate change scenarios. Instances of air temperatures below CTmin were predicted to decline in frequency for the widespread lowland and both highland species. Air temperatures of high altitude sites were not predicted to exceed the CTmax of either highland species throughout the 21st century. In contrast, the widespread lowland species is predicted to experience air temperatures in excess of CTmax on 1 or 2 days by three of six global circulation models from 2068-2096. To estimate climate change effects on activity we reran the thermal tolerance models using minimum and maximum temperatures selected for activity. A net gain in available activity time was predicted under climate change for all three species while air temperatures were predicted to exceed maximum temperatures selected for activity with increasing frequency, the change was not as great as the predicted decline in air temperatures below minimum temperatures selected for activity. We hypothesise that the major effect of rising air temperatures under climate change is an increase in available activity period for both the widespread lowland and highland species. The consequences of a greater available activity period will depend on the extent to which changes in climate alters other related factors, such as the nature and level of competition between the respective species.
Publisher: Springer Science and Business Media LLC
Date: 25-10-2021
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/WR05063
Abstract: Artificial food patches were used to examine whether red bellied-pademelons (Thylogale billiardierii) and Bennett’s wallabies (Macropus rufogriseus rufogriseus) altered their foraging behaviour in an open habitat (a young plantation) in response to distance from cover, used as a surrogate for predation risk. Analyses using the full dataset showed no significant relationship between the amount of food eaten at a station and any of the cover variables. In contrast, regression analyses of the upper bounds dataset indicated that both increased distance from windrow (2.5-m-high stacks of burnt wood) and from nearest cover (windrow or forest at plantation edge) significantly reduced the amount of food consumed at a station. This indicates that distance from cover acts as a constraint on the amount of food eaten. When the feeding-station data were overlayed onto a map of scat densities across the study site, the amount of food eaten was positively related to the density of scats of both red-bellied pademelons and Bennett’s wallabies. Our results demonstrate that these macropods trade-off increased foraging benefits in order to forage closer to protective cover. Furthermore, they represent the first time that artificial food patches, with progressively decreasing reward per search effort, have been used to assess foraging behaviour in macropods. This opens up a wide range of research opportunities aimed at examining macropod foraging, with both ecological and practical applications.
Publisher: Wiley
Date: 29-06-2009
Publisher: Elsevier BV
Date: 06-2009
Publisher: Wiley
Date: 06-2011
DOI: 10.1111/J.1749-4877.2011.00237.X
Abstract: Recent research suggests that oxidative stress, via its links to metabolism and senescence, is a key mechanism linking life history traits such as fecundity and growth with survival however, this has rarely been put under empirical scrutiny within free-living populations. Using a wild population of live-bearing skinks, we explored how plasma antioxidant activity (OXY), reactive oxidative metabolites (ROM), and the estimated oxidative stress index are associated with female and male life history. We found that male skinks have a significantly higher ROM and estimated oxidative stress index than female skinks, but this was not accompanied by a sex difference in mortality. Both sexes showed a non-linear association between OXY and age, indicating that the oldest and youngest in iduals had the lowest OXY. Interestingly, female skinks with high OXY showed a decreased probability of survival to the following season. However, we found no significant associations between female reproductive investment (litter size or litter mass) or parturition date (i.e. metabolism) and oxidative status. Combined, our results offer mixed support for a role of oxidative stress in mediating life history traits and suggest that future studies need to explore oxidative stress during vitellogenesis in addition to using an intra-in idual approach to understand the cost of reproduction and patterns of aging.
Publisher: The Royal Society
Date: 04-03-2009
Abstract: In idual differences in behaviour are ubiquitous in nature. Despite the likely role of selection in maintaining these differences, there are few demonstrations of their fitness consequences in wild populations and, consequently, the mechanisms that link behavioural variation to variation in fitness are poorly understood. Specifically, the consequences of consistent in idual differences in behaviour for the evolution of social and mating strategies have rarely been considered. We examined the functional links between variation in female aggression and her social and mating strategies in a wild population of the social lizard Egernia whitii . We show that female Egernia exhibit temporally consistent aggressive phenotypes, which are unrelated to body size, territory size or social density. A female's aggressive phenotype, however, has strong links to her mode of paternity acquisition (within- versus extra-pair paternity), with more aggressive females having more offspring sired by extra-pair males than less aggressive females. We discuss the potential mechanisms by which female aggression could underpin mating strategies, such as the pursuit/acceptance of extra-pair copulations. We propose that a deeper understanding of the evolution and maintenance of social and mating systems may result from an explicit focus on in idual-level female behavioural phenotypes and their relationship with key reproductive strategies.
Publisher: Elsevier BV
Date: 07-2015
DOI: 10.1016/J.CUB.2015.02.070
Abstract: While et al's quick guide to Egernia lizards, a group of social lizards from Austalasia.
Publisher: The Royal Society
Date: 04-2018
Abstract: Stressful conditions experienced during early development can have deleterious effects on offspring morphology, physiology and behaviour. However, few studies have examined how developmental stress influences an in idual's cognitive phenotype. Using a viviparous lizard, we show that the availability of food resources to a mother during gestation influences a key component of her offspring's cognitive phenotype: their decision-making. Offspring from females who experienced low resource availability during gestation did better in an anti-predatory task that relied on spatial associations to guide their decisions, whereas offspring from females who experienced high resource availability during gestation did better in a foraging task that relied on colour associations to inform their decisions. This shows that the prenatal environment can influence decision-making in animals, a cognitive trait with functional implications later in life.
Publisher: Wiley
Date: 29-01-2015
DOI: 10.1111/JZO.12217
Publisher: Wiley
Date: 21-06-2023
Abstract: The thermal sensitivity of early life stages can play a fundamental role in constraining species distributions. For egg‐laying ectotherms, cool temperatures often extend development time and exacerbate developmental energy cost. Despite these costs, egg laying is still observed at high latitudes and altitudes. How embryos overcome the developmental constraints posed by cool climates is crucial knowledge for explaining the persistence of oviparous species in such environments and for understanding thermal adaptation more broadly. Here, we studied maternal investment and embryo energy use and allocation in wall lizards spanning altitudinal regions, as potential mechanisms that enable successful development to hatching in cool climates. Specifically, we compared population‐level differences in (1) investment from mothers (egg mass, embryo retention and thyroid yolk hormone concentration), (2) embryo energy expenditure during development, and (3) embryo energy allocation from yolk towards tissue. We found evidence that energy expenditure was greater under cool compared with warm incubation temperatures. Females from relatively cool regions did not compensate for this energetic cost of development by producing larger eggs or increasing thyroid hormone concentration in yolk. Instead, embryos from the high‐altitude region used less energy to complete development, that is, they developed faster without a concomitant increase in metabolic rate, compared with those from the low‐altitude region. Embryos from high altitudes also allocated relatively more energy towards tissue production, hatching with lower residual yolk: tissue ratios than low‐altitude region embryos. These results are consistent with local adaptation to cool climate and suggest that this is underpinned by mechanisms that regulate embryonic utilisation of yolk reserves and its allocation towards tissue, rather than shifts in maternal investment of yolk content or composition.
Publisher: Frontiers Media SA
Date: 10-12-2021
Abstract: There is great ersity in social behavior across the animal kingdom. Understanding the factors responsible for this ersity can help inform theory about how sociality evolves and is maintained. The Australian Tree Skink ( Egernia striolata ) exhibits inter- and intra-population variability in sociality and is therefore a good system for informing models of social evolution. Here, we conducted a multi-year study of a Tree Skink population to describe intra-population variation in the social organization and mating system of this species. Skinks aggregated in small groups of 2–5 in iduals, and these aggregations were typically associated with shared shelter sites (crevices and hollows within rocks and trees). Aggregations were typically made up of one or more adult females and, often, one male and/or juvenile(s). Social network and spatial overlap analyses showed that social associations were strongly biased toward kin. Tree skinks also exhibited high site fidelity regardless of age or sex. There were high levels of genetic monogamy observed with most females (87%) and males (68%) only breeding with a single partner. Our results indicate that Tree Skinks reside in small family groups and are monogamous, which corresponds with existing research across populations. Similar to previous work, our study area consisted of discrete habitat patches (i.e., rock outcrops, trees, or both), which likely limits offspring dispersal and promotes social tolerance between parents and their offspring. Our study clearly demonstrates that there is intra-population variability in Tree Skink social behavior, but it also provides evidence that there is a high degree of inter-population consistency in sociality across their geographic range. We also highlight promising possible avenues for future research, specifically discussing the importance of studying the nature and extent of Tree Skink parental care and quantifying the fitness outcomes of kin-based sociality in this species, which are topics that will further our understanding of the mechanisms underlying variation in vertebrate social behavior.
Publisher: The Company of Biologists
Date: 08-03-2022
DOI: 10.1242/JEB.243369
Abstract: During the vulnerable stages of early life, most ectothermic animals experience hourly and diel fluctuations in temperature as air temperatures change. While we know a great deal about how different constant temperatures impact the phenotypes of developing ectotherms, we know remarkably little about the impacts of temperature fluctuations on the development of ectotherms. In this study, we used a meta-analytic approach to compare the mean and variance of phenotypic outcomes from constant and fluctuating incubation temperatures across reptile species. We found that fluctuating temperatures provided a small benefit (higher hatching success and shorter incubation durations) at cool mean temperatures compared with constant temperatures, but had a negative effect at warm mean temperatures. In addition, more extreme temperature fluctuations led to greater reductions in embryonic survival compared with moderate temperature fluctuations. Within the limited data available from species with temperature-dependent sex determination, embryos had a higher chance of developing as female when developing in fluctuating temperatures compared with those developing in constant temperatures. With our meta-analytic approach, we identified average mean nest temperatures across all taxa where reptiles switch from receiving benefits to incurring costs when incubation temperatures fluctuate. More broadly, our study indicates that the impact of fluctuating developmental temperature on some phenotypes in ectothermic taxa are likely to be predictable via integration of developmental temperature profiles with thermal performance curves.
Publisher: Wiley
Date: 19-11-2009
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.YHBEH.2010.03.016
Abstract: In idual hormone profiles can be important generators of phenotypic variation. Despite this, work on the consequences of hormone profiles has traditionally ignored the large inter-in idual variation within natural populations. However, recent research has advocated the need to explicitly consider this variation and address its consequences for selection. One of the key steps in this process is examining repeatability in hormone profiles and their links to behavioral traits under selection. In this study we show that in iduals within a free-ranging population of the Australian lizard Egernia whitii exhibit temporal repeatability in their circulating baseline testosterone concentrations as well as their aggressive response towards conspecific intruders. Furthermore, we show significant, sex-specific links between testosterone and aggression. Specifically, testosterone and aggression is negatively linked in males, while there is no relationship in females. As conspecific aggression has significant consequences for fitness-related traits (parental care, mating strategies) in this species, inter-in idual variation in testosterone concentrations, through their effects on aggression, could have important implications for in idual fitness. We discuss the potential causes and consequences of hormonal repeatability as well as provide explanations for its sex-specific links with aggression. Specifically, we suggest that these patterns are the result of alternative hormonal pathways governing aggression within Egernia and may indicate a decoupling of aggression and testosterone across the sexes.
Publisher: The Company of Biologists
Date: 15-05-2023
DOI: 10.1242/BIO.059967
Abstract: Developmental conditions can profoundly impact key life history traits of the in idual. In cases where offspring sex is driven by developmental reaction norms, permanent changes to the phenotype can fundamentally alter life history trajectories. Sex determination mechanisms in reptiles are remarkably erse, including well-characterised genetic and temperature-dependent sex determination. In rarer, but increasingly more commonly documented cases, sex can also be determined by a combination of the two, with temperature overriding the genetically determined sex. Thus, sex-by-temperature interactions is a mechanism that can be contextually labile, where reaction norms of sex against developmental environment might only be observable under certain conditions. We examine the effects of incubation temperature on hatchling sex in an oviparous lizard with clearly defined heteromorphic sex chromosomes presumed to determine sex solely on a genetic basis. We also test the repeatability of our results by replicating incubation experiments across 3 years. We show that warmer temperatures may override chromosomal sex and cause an overproduction of daughters. However, this effect was inconsistent among years, with high temperature only resulting in a daughter-significant bias in one year. Warm-incubated daughters were more efficient at converting yolk into tissue, which would allow for greater resource allocation to other fitness-related processes, such as growth. This suggests that thermolabile sex determination could be a trait under selection. More energy-efficient embryos also produced faster-growing offspring, suggesting that energy utilization patterns of the embryo were maintained into the juvenile stage, which could have important implications for the ontogenetic development and evolution of life histories.
Publisher: Springer Science and Business Media LLC
Date: 16-10-2019
DOI: 10.1007/S00442-019-04530-W
Abstract: Telomere dynamics vary fundamentally between endothermic populations and species as a result of differences in life history, yet we know little about these patterns in ectotherms. In ectotherms, the relationships between climate, metabolism and life history suggest that telomere attrition should be higher at relatively high environmental temperatures compared to relatively low environmental temperatures, but these effects may vary between populations due to local adaptation. To address this hypothesis, we s led reactive oxygen species (ROS) and telomere length of lizards from warm lowland and cool highland populations of a climatically widespread lizard species that we exposed to hot or cold basking treatments. The hot treatment increased relative telomere length compared to the cold treatment independent of climatic origin or ROS levels. Lizards from the cool highland region had lower ROS levels than those from the warm lowland region. Within the highland lizards, ROS increased more in the cold basking treatment than the hot basking treatment. These results are in the opposite direction to those predicted, suggesting that the relationships between temperature, metabolism, ROS and telomere dynamics are not straightforward. Future work incorporating detailed understanding of the thermal reaction norms of these and other linked traits is needed to fully understand these processes.
Publisher: Wiley
Date: 22-01-2014
DOI: 10.1111/MEC.12618
Abstract: Population viscosity can have major consequences for adaptive evolution, in particular for phenotypes involved in social interactions. For ex le, population viscosity increases the probability of mating with close kin, resulting in selection for mechanisms that circumvent the potential negative consequences of inbreeding. Female promiscuity is often suggested to be one such mechanism. However, whether avoidance of genetically similar partners is a major selective force shaping patterns of promiscuity remains poorly supported by empirical data. Here, we show (i) that fine-scale genetic structure constrains social mate choice in a pair-bonding lizard, resulting in in iduals pairing with genetically similar in iduals, (ii) that these constraints are circumvented by multiple mating with less related in iduals and (iii) that this results in increased heterozygosity of offspring. Despite this, we did not detect any significant effects of heterozygosity on offspring or adult fitness or a strong relationship between pair relatedness and female multiple mating. We discuss these results within the context of incorporating the genetic context dependence of mating strategies into a holistic understanding of mating system evolution.
Publisher: Springer Science and Business Media LLC
Date: 11-12-2017
DOI: 10.1038/S41467-017-02220-W
Abstract: Identifying factors responsible for the emergence and evolution of social complexity is an outstanding challenge in evolutionary biology. Here we report results from a phylogenetic comparative analysis of over 1000 species of squamate reptile, nearly 100 of which exhibit facultative forms of group living, including prolonged parent–offspring associations. We show that the evolution of social groupings among adults and juveniles is overwhelmingly preceded by the evolution of live birth across multiple independent origins of both traits. Furthermore, the results suggest that live bearing has facilitated the emergence of social groups that remain stable across years, similar to forms of sociality observed in other vertebrates. These results suggest that live bearing has been a fundamentally important precursor in the evolutionary origins of group living in the squamates.
Publisher: Wiley
Date: 16-12-2017
DOI: 10.1111/JEB.13219
Abstract: Females are predicted to alter sex allocation when ecological, physiological and behavioural variables have different consequences on the fitness of male and female offspring. Traditionally, tests of sex allocation have examined single causative factors, often ignoring possible interactions between multiple factors. Here, we used a multifactorial approach to examine sex allocation in the viviparous skink, Niveoscincus ocellatus. We integrated a 16-year observational field study with a manipulative laboratory experiment to explore whether the effects of the maternal thermal environment interact with the resources available to females for reproduction to affect sex allocation decisions. We found strong effects of temperature on sex allocation in the field, with females born in warm conditions and males in cold conditions however, this was not replicated in the laboratory. In contrast, we found no effect of female resource availability on sex allocation, either independently, or in interaction with temperature. These results corresponded with an overall lack of an effect of resource availability on any of the life history traits that we predicted would mediate the benefits of differential sex allocation in this system, suggesting that selection for sex allocation in response to resource availability may be relatively weak. Combined, these results suggest that temperature may be the predominant factor driving sex allocation in this system.
Publisher: Brill
Date: 2011
Publisher: CRC Press
Date: 06-02-2019
Publisher: Wiley
Date: 28-12-2010
Publisher: Wiley
Date: 19-04-2011
DOI: 10.1111/J.1558-5646.2011.01303.X
Abstract: Plastic responses to temperature during embryonic development are common in ectotherms, but their evolutionary relevance is poorly understood. Using a combination of field and laboratory approaches, we demonstrate altitudinal ergence in the strength of effects of maternal thermal opportunity on offspring birth date and body mass in a live-bearing lizard (Niveoscincus ocellatus). Poor thermal opportunity decreased birth weight at low altitudes where selection on body mass was negligible. In contrast, there was no effect of maternal thermal opportunity on body mass at high altitudes where natural selection favored heavy offspring. The weaker effect of poor maternal thermal opportunity on offspring development at high altitude was accompanied by a more active thermoregulation and higher body temperature in highland females. This may suggest that passive effects of temperature on embryonic development have resulted in evolution of adaptive behavioral compensation for poor thermal opportunity at high altitudes, but that direct effects of maternal thermal environment are maintained at low altitudes because they are not selected against. More generally, we suggest that phenotypic effects of maternal thermal opportunity or incubation temperature in reptiles will most commonly reflect weak selection for canalization or selection on maternal strategies rather than adaptive plasticity to match postnatal environments.
Publisher: CSIRO Publishing
Date: 28-09-2020
DOI: 10.1071/ZO21017
Abstract: Australian lizards are a erse group distributed across the continent and inhabiting a wide range of environments. Together, they exhibit a remarkable ersity of reproductive morphologies, physiologies, and behaviours that is broadly representative of vertebrates in general. Many reproductive traits exhibited by Australian lizards have evolved independently in multiple lizard lineages, including sociality, complex signalling and mating systems, viviparity, and temperature-dependent sex determination. Australian lizards are thus outstanding model organisms for testing hypotheses about how reproductive traits function and evolve, and they provide an important basis of comparison with other animals that exhibit similar traits. We review how research on Australian lizard reproduction has contributed to answering broader evolutionary and ecological questions that apply to animals in general. We focus on reproductive traits, processes, and strategies that are important areas of current research, including behaviours and signalling involved in courtship mechanisms involved in mating, egg production, and sperm competition nesting and gestation sex determination and finally, birth in viviparous species. We use our review to identify important questions that emerge from an understanding of this body of research when considered holistically. Finally, we identify additional research questions within each topic that Australian lizards are well suited for reproductive biologists to address.
Publisher: Wiley
Date: 09-12-2018
DOI: 10.1111/ELE.13195
Publisher: Elsevier BV
Date: 10-2008
Publisher: Oxford University Press (OUP)
Date: 29-09-2018
Publisher: Oxford University Press (OUP)
Date: 02-01-2017
Publisher: Wiley
Date: 06-2010
DOI: 10.1111/J.1749-4877.2010.00201.X
Abstract: Climate change is already impacting species around the world. Although most focus has been on the effect of temperature, changes in climatic variables other than temperature are also expected to drive biological change. Current models suggest that ectotherms, such as reptiles, will be strongly affected by climate change however, data from natural populations are rare. Here, we use extensive data from 2 populations of a viviparous lizard (Niveoscincus ocellatus Gray, 1845) at the climatic extreme of the species distribution. We examine the effects of climate at a local, a regional and a global scale (thus, integrating a suite of variables at different spatial and temporal scales) on 2 key life history traits: offspring date of birth and size at birth. Overall, our results show that across 9 years of study, local temperature had strong effects on the offspring date of birth but not on the size at birth. Therefore, a rapid increase in local temperature throughout the species range (as predicted under global warming scenarios) is likely to affect phenological processes with potential concomitant effects on offspring fitness and survival.
Publisher: Wiley
Date: 27-02-2020
DOI: 10.1111/AEC.12864
Publisher: Elsevier BV
Date: 05-2021
Publisher: Oxford University Press (OUP)
Date: 21-11-2007
No related organisations have been discovered for Geoffrey While.
Start Date: 12-2021
End Date: 12-2024
Amount: $340,576.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2018
End Date: 12-2023
Amount: $300,985.00
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2015
End Date: 12-2017
Amount: $334,200.00
Funder: Australian Research Council
View Funded ActivityStart Date: 02-2015
End Date: 12-2018
Amount: $369,453.00
Funder: Australian Research Council
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