ORCID Profile
0000-0002-2924-9040
Current Organisations
University of Guelph
,
Macquarie University
,
Carleton University
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Research Topics
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.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Evolutionary Impacts of Climate Change | Microbial Ecology | Terrestrial Ecology | Host-Parasite Interactions | Ecology | Ecological Physiology | Evolutionary Biology | Biological Adaptation
ANZSRC Socio-Economic Objective (SEO)
Ecosystem Adaptation to Climate Change | Flora, Fauna and Biodiversity of environments not elsewhere classified | Ecosystem Assessment and Management at Regional or Larger Scales | Expanding Knowledge in the Biological Sciences |
Related Links
Publications
Curvilinear telomere length dynamics in a squamate reptile
Publisher: Wiley
Date: 17-10-2016
Behavioural divergence during biological invasions: a study of cane toads (Rhinella marina) from contrasting environments in Hawai'i
Publisher: The Royal Society
Date: 04-2018
DOI: 10.1098/RSOS.180197
Abstract: Invasive species must deal with novel challenges, both from the alien environment and from pressures arising from range expansion per se (e.g. spatial sorting). Those conditions can create geographical variation in behaviour across the invaded range, as has been documented across regions of Australia invaded by cane toads range-edge toads are more exploratory and willing to take risks than are conspecifics from the range-core. That behavioural ergence might be a response to range expansion and invasion per se , or to the different environments encountered. Climate differs across the cane toads' invasion range from the wet tropics of Queensland to the seasonally dry climates of northwestern Western Australia. The different thermal and hydric regimes may affect behavioural traits via phenotypic plasticity or through natural selection. We cannot tease apart the effects of range expansion versus climate in an expanding population but can do so in a site where the colonizing species was simultaneously released in all suitable areas, thus removing any subsequent phase of range expansion. Cane toads were introduced to Hawai'i in 1932 and thence to Australia in 1935. Toads were released in all major sugarcane-growing areas in Hawai'i within a 12-month period. Hence, Hawai'ian cane toads provide an opportunity to examine geographical ergence in behavioural traits in a climatically erse region (each island has both wet and dry sides) in the absence of range expansion subsequent to release. We conducted laboratory-based behavioural trials testing exploration, risk-taking and response to novelty using field-caught toads from the wet and dry sides of two Hawai'ian islands (Oahu and Hawai'i). Toads from the dry side of Oahu had a higher propensity to take risks than did toads from the dry side of Hawai'i. Toads from Oahu were also more exploratory than were conspecifics from the island of Hawai'i. However, toads from wet versus dry climates were similar in all behaviours that we scored, suggesting that founder effects, genetic drift, or developmentally plastic responses to ecological factors other than climate may have driven behavioural ergence between islands.
Host-parasite interactions during a biological invasion: The fate of lungworms (Rhabdias spp.) inside native and novel anuran hosts
Publisher: Elsevier BV
Date: 08-2015
Proximate mechanisms underlying the rapid modification of phenotypic traits in cane toads (Rhinella marina) across their invasive range within Australia
Publisher: Oxford University Press (OUP)
Date: 19-11-2019
Smoking prevalence and attributable disease burden in 195 countries and territories, 1990–2015: a systematic analysis from the Global Burden of Disease Study 2015
Publisher: Elsevier BV
Date: 05-2017
Dehydration enhances innate immunity in a semiaquatic snake from the wet-dry tropics
Publisher: Wiley
Date: 14-03-2019
DOI: 10.1002/JEZ.2260
Abstract: Dehydration is considered a physiological challenge, and many organisms live in environments that undergo periods of reduced water availability that can lead to dehydration. Recent studies have found a positive relationship between dehydration and innate immune function in animals adapted to xeric or semixeric environments. To explore the generality of this relationship, we examined the impact of dehydration on innate immune performance in water pythons (Liasis fuscus), a semiaquatic snake from the wet-dry tropics of Australia. We collected blood s les from male and female water pythons held in the laboratory without food and water for 4 weeks. We also collected blood from free-ranging snakes throughout the Austral dry-season. We evaluated plasma osmolality and innate immune function (agglutination, lysis, and bacterial-killing ability) and found that increased osmolality, whether manipulated in the laboratory or as a result of natural water limitation, resulted in enhanced aspects of innate immune performance. Counter-intuitively, snakes in the wild became more hydrated as the dry season progressed, suggesting the dehydrated snakes move to water sources periodically to rehydrate. Comparing our data with those from previous studies, we suspect species ergence in the level of dehydration (i.e., hyperosmolality) that triggers enhanced immune capabilities.
Global, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990–2017: a systematic analysis for the Global B
Publisher: Elsevier BV
Date: 11-2018
Global, regional, and national burden of traumatic brain injury and spinal cord injury, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016
Publisher: Elsevier BV
Date: 2019
Using phytohaemagglutinin to determine immune responsiveness in saltwater crocodiles (Crocodylus porosus)
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/ZO13041
Abstract: Immune responsiveness, the ability of an organism to effectively respond immunologically following antigenic exposure, is an essential component of life history, as organisms require effective immune functionality in order to grow, survive and reproduce. However, immune status is also associated with concomitant trade-offs in these physiological functions. Herein we demonstrate the validation of phytohaemagglutinin (PHA) injection in saltwater crocodiles, Crocodylus porosus, to assess cellular immune responsiveness. Following injection of 2 mg mL–1 PHA into the hind toe webbing, we observed a peak swelling response 12 h after injection, with PHA inducing increased thickness compared with webs injected with phosphate-buffered saline (PBS) (F5,518 = 145.13, P 0.001). Subsequent injections increased responsiveness relative to the primary injection response (F5,290 = 2.92, P = 0.029), suggesting that PHA exposure induced immunological memory, a tenet of acquired immunity. Histological examination revealed that PHA-injected toe webs displayed increased numbers of leukocytes (granulocytes, macrophages, and lymphocytes) relative to PBS-injected webs, with peak leukocytic infiltrate observed 12 h after injection. We suggest the use of PHA injection in crocodilians as a measure of cellular immune responsiveness in agricultural (production and animal welfare), ecological, and toxicological contexts.
Pest control by the public
Publisher: Elsevier BV
Date: 09-2020
Activity patterns and movements of free-ranging bluetongue lizards (Tiliqua scincoides intermedia and Tiliqua multifasciata) in the Australian wet-dry tropics
Publisher: Society for the Study of Amphibians and Reptiles
Date: 09-2014
DOI: 10.1670/12-256
An invasive tree facilitates the persistence of native rodents on an over-grazed floodplain in tropical Australia
Publisher: Wiley
Date: 22-09-2017
DOI: 10.1111/AEC.12454
Size and sex matter: infection dynamics of an invading parasite (the pentastome Raillietiella frenatus) in an invading host (the cane toad Rhinella marina)
Publisher: Cambridge University Press (CUP)
Date: 20-07-2012
Sexual communication in cane toads, Chaunus marinus: what cues influence the duration of amplexus?
Publisher: Elsevier BV
Date: 04-2008
Adaptation or preadaptation: Why are keelback snakes (Tropidonophis mairii) less vulnerable to invasive cane toads (Bufo marinus) than are other Australian snakes?
Publisher: Springer Science and Business Media LLC
Date: 19-03-2011
The life aquatic: an association between habitat type and skin thickness in snakes
Publisher: Oxford University Press (OUP)
Date: 15-10-2019
DOI: 10.1093/BIOLINNEAN/BLZ136
Abstract: An aquatic animal faces challenges not encountered by its terrestrial counterparts, promoting adaptive responses in multiple traits. For ex le, a thicker dermis might protect snakes when they are pushed against sharp objects by water currents, and might enable a snake to shed fouling organisms attached to its skin. We thus predicted that marine snakes should have thicker skin than terrestrial species, and that smaller sea snakes should have relatively thicker skin (because absolute, not relative, thickness determines vulnerability to fouling). Measurements of 192 snakes of 44 species supported those predictions. Many (but not all) sea snakes have skins 50% thicker than those of terrestrial and hibious snake species, representing multiple independent evolutionary origins of thicker skin (in acrochordids, Laticauda sea kraits and both main clades of hydrophiine sea snakes). Marine snakes showed different allometries of skin thickness compared with their terrestrial counterparts larger snakes had thicker skin within and among species of hibious and terrestrial snakes, but larger aquatic snake species had thinner skin compared with smaller taxa. Interspecific variation in skin thickness was primarily due to increased collagen in the deep dermis, a physical barrier well suited to protecting against physical injury and to resisting penetration by epibionts.
Corticosterone-immune interactions during captive stress in invading Australian cane toads (Rhinella marina)
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.YHBEH.2012.06.001
Abstract: Vertebrates cope with physiological challenges using two major mechanisms: the immune system and the hypothalamic pituitary-adrenal axis (e.g., the glucocorticoid stress response). Because the two systems are tightly integrated, we need simultaneous studies of both systems, in a range of species, to understand how vertebrates respond to novel challenges. To clarify how glucocorticoids modulate the hibian immune system, we measured three immune parameters and plasma corticosterone (CORT), before and after inflicting a stressor (capture and captive confinement) on introduced cane toads (Rhinella marina) near their invasion front in Australia. Stress increased CORT levels, decreased complement lysis capacity, increased leukocyte oxidative burst, and did not change heterologous erythrocyte agglutination. The strength of the CORT response was positively correlated with leukocyte oxidative burst, and morphological features associated with invasiveness in cane toads (relative leg length) were correlated with stress responsiveness. No immune parameter that we measured was affected by a toad's infection by a parasitic nematode (Rhabdias pseudosphaerocephala), but the CORT response was muted in infected versus uninfected toads. These results illustrate the complex immune-stress interactions in wild populations of a non-traditional model vertebrate species, and describe immune adaptations of an important invasive species.
Comparisons through time and space suggest rapid evolution of dispersal behaviour in an invasive species
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/WR08021
Abstract: During a biological invasion, we expect that the expanding front will increasingly become dominated by in iduals with better dispersal abilities. Over many generations, selection at the invasion front thus will favour traits that increase dispersal rates. As a result of this process, cane toads (Bufo marinus) are now spreading through tropical Australia about 5-fold faster than in the early years of toad invasion but how have toads changed to make this happen? Here we present data from radio-tracking of free-ranging cane toads from three populations (spanning a 15-year period of the toads’ Australian invasion, and across 1800 km). Our data reveal dramatic shifts in behavioural traits (proportion of nights when toads move from their existing retreat-site to a new one, and distance between those successive retreat-sites) associated with the rapid acceleration of toad invasion. Over a maximum period of 70 years (~50 generations), cane toads at the invasion front in Australia apparently have evolved such that populations include a higher proportion of in iduals that make long, straight moves.
Sexual and geographical divergence in head widths of invasive cane toads, Rhinella marina (Anura: Bufonidae), is driven by both rapid evolution and plasticity
Publisher: Oxford University Press (OUP)
Date: 03-05-2018
The costs of parasite infection: Effects of removing lungworms on performance, growth and survival of free‐ranging cane toads
Publisher: Wiley
Date: 05-10-2017
Spatial ecology of hatchling water pythons (Liasis fuscus) in tropical Australia
Publisher: Cambridge University Press (CUP)
Date: 03-2009
DOI: 10.1017/S0266467408005774
Abstract: Young snakes are rarely seen in the field and little is known about their habits, mostly because they are too small for radio-telemetry (the primary method for studying snake spatial ecology). However, the offspring of some larger species can be fitted with transmitters and we investigated the spatial ecology and habitat use of ten hatchling water pythons ( Liasis fuscus : Pythonidae) in the floodplain of the Adelaide River, tropical Australia. Patterns of habitat use in the late wet season and during the dry season were similar to those of adults tracked in the same vicinity in an earlier study. Soon after release the young snakes moved to the floodplain, avoiding pasture areas. Diurnal refuge sites were typically in the base of grass clumps or below the soil surface, especially in sites with thick vegetation and deep, wide soil cracks. Adult snakes are more sedentary but move longer absolute distances (mean ± SE = 252 ± 50 m wk −1 ) than hatchlings (66.3 ± 41 m wk −1 ). However, hatchling snakes moved longer distances relative to body size (84.4 ± 1.1 body lengths wk −1 ) than did the previously studied adults (66.0 ± 1.1 body lengths wk −1 ). Mean and minimum body temperatures of the hatchlings were correlated with mean and minimum air temperatures, respectively.
Population dynamics of the sea snake Emydocephalus annulatus (Elapidae, Hydrophiinae)
Publisher: Springer Science and Business Media LLC
Date: 19-10-2021
DOI: 10.1038/S41598-021-00245-2
Abstract: For sea snakes as for many types of animals, long-term studies on population biology are rare and hence, we do not understand the degree to which annual variation in population sizes is driven by density-dependent regulation versus by stochastic abiotic factors. We monitored three populations of turtle-headed sea snakes ( Emydocephalus annulatus ) in New Caledonia over an 18-year period. Annual recruitment (% change in numbers) showed negative density-dependence: that is, recruitment increased when population densities were low, and decreased when densities were high. Windy weather during winter increased survival of neonates, perhaps by shielding them from predation but those same weather conditions reduced body condition and the reproductive output of adult snakes. The role for density-dependence in annual dynamics of these populations is consistent with the slow, K-selected life-history attributes of the species and the influence of weather conditions on reproductive output suggests that females adjust their allocation to reproduction based on food availability during vitellogenesis.
Influence of lung parasites on the growth rates of free-ranging and captive adult cane toads
Publisher: Springer Science and Business Media LLC
Date: 14-11-2011
DOI: 10.1007/S00442-010-1836-5
Abstract: Many parasites affect the viability of their hosts, but detailed studies combining empirical data from both the field and the laboratory are limited. Consequently, the nature and magnitude of such effects are poorly known for many important host-parasite systems, including macroparasites of hibians. We examined the effects of lungworm (Rhabdias pseudosphaerocephala) infections in cane toads (Bufo marinus) within their invasive Australian range. The host-specificity of this parasite suggests that it might serve as a biological control agent for toads in Australia, if infection proves to reduce toad viability. Mark-recapture studies in the field (near Darwin, Northern Territory) revealed lowered growth rates in infected adult toads when compared to uninfected toads, and a laboratory experiment confirmed causality: experimental infection with R. pseudosphaerocephala reduce toad growth rates. In combination with previous work on the current host-parasite system, it is now evident that nematode lungworms reduce the viability of both newly metamorphosed and adult cane toads, and do so in the field as well as in the laboratory. Rhabdias pseudosphaerocephala may be a valuable component of a biological control strategy for cane toads in Australia.
Influence of weather conditions on activity of tropical snakes
Publisher: Wiley
Date: 21-11-2002
Global, regional, and national burden of Parkinson's disease, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016
Publisher: Elsevier BV
Date: 11-2018
Spatial ecology of slatey-grey snakes (Stegonotus cucullatus, Colubridae) on a tropical Australian floodplain
Publisher: Cambridge University Press (CUP)
Date: 19-10-2005
DOI: 10.1017/S0266467405002671
Abstract: The extent, sequence, synchrony and correlates of diel displacements by animals can provide powerful insights into the ecological and social factors that shape an organism's day-to-day activities, but detailed data on spatial ecology are available for very few tropical taxa. Radiotelemetric monitoring of 25 slatey-grey snakes ( Stegonotus cucullatus ) on a floodplain in the Australian wet-dry tropics for periods of 40 to 355 d (mean=195 d, 136 locations per snake) provided extensive information on habitat use, movement patterns and home range size of these large slender-bodied colubrids. All radio-tracked animals were nocturnal, sheltering by day in soil cracks and beneath tree roots and debris. Snakes did not appear to move between 61% of successive locations and timing of movements was not synchronized among snakes. Most displacements were small ( m), with males moving further and more often than did females. However, nesting females made occasional long-distance movements, travelling 100–400m to forested areas to oviposit but then returning to their usual home ranges. Snakes of both sexes moved further and more often during the wet-season than the dry-season. Snakes typically moved on a few successive nights then remained sedentary for the next few days, apparently reflecting cessation of activity as soon as a meal was obtained. Home ranges were small (2.9–7.4 ha) and most snakes remained in the same area throughout the year, providing a strong contrast in this respect to the large and seasonally dynamic home ranges of sympatric acrochordid and pythonid snakes.
Resource availability and sexual size dimorphism: differential effects of prey abundance on the growth rates of tropical snakes
Publisher: Wiley
Date: 24-04-2017
Virgins in the vanguard: Low reproductive frequency in invasion-front cane toads
Publisher: Oxford University Press (OUP)
Date: 14-07-2015
DOI: 10.1111/BIJ.12618
RADIOTELEMETRY OF BODY TEMPERATURES OF FREE-RANGING SNAPPING TURTLES (CHELYDRA-SERPENTINA) DURING SUMMER
Publisher: Canadian Science Publishing
Date: 08-1990
DOI: 10.1139/Z90-246
Abstract: We wished to determine whether free-ranging snapping turtles (Chelydra serpentina) would use aquatic and atmospheric basking to maintain body temperature at the mean temperature (28–30 °C) selected by snapping turtles placed in a controlled aquatic thermal gradient. Body temperatures from eight adult snapping turtles in three different lakes in Algonquin Provincial Park were monitored by radiotelemetry during July and August 1987. Mean body temperature of all eight turtles over the study period was 22.7 °C, and mean temperature of every in idual was well below the reported mean selected temperature for this species. The turtles did not maintain body temperatures near the available maximum environmental temperature. The mean body temperatures of the turtles were not significantly different among the three study lakes although these lakes had different physical characteristics. Similarly, there were no significant differences, among in idual turtles, between air temperatures or operative environmental temperatures recorded concurrently with their body temperatures Nevertheless, mean body temperatures differed significantly among in iduals foraging tactics, metabolic rates, and home range structure may account for these differences.
Do microbiota in the soil affect embryonic development and immunocompetence in hatchling reptiles?
Publisher: Frontiers Media SA
Date: 05-01-2022
Abstract: Reptile eggs develop in intimate association with microbiota in the soil, raising the possibility that embryogenesis may be affected by shifts in soil microbiota caused by anthropogenic disturbance, translocation of eggs for conservation purposes, or laboratory incubation in sterile media. To test this idea we incubated eggs of keelback snakes ( Tropidonophis mairii , Colubridae) in untreated versus autoclaved soil, and injected lipopolysaccharide (LPS) into the egg to induce an immune response in the embryo. Neither treatment modified hatching success, water uptake, incubation period, or white-blood-cell profiles, but both treatments affected hatchling size. Eggs incubated on autoclaved soil produced smaller hatchlings than did eggs on untreated soil, suggesting that heat and/or pressure treatment decrease the soil’s suitability for incubation. Injection of LPS reduced hatchling size, suggesting that the presence of pathogen cues disrupts embryogenesis, possibly by initiating immune reactions unassociated with white-blood-cell profiles. Smaller neonates had higher ratios of heterophils to leucocytes, consistent with higher stress in smaller snakes, or body-size effects on investment into different types of immune cells. Microbiota in the incubation medium thus can affect viability-relevant phenotypic traits of hatchling reptiles. We need further studies to explore the complex mechanisms and impacts of environmental conditions on reptilian embryogenesis.
The accelerating invasion: dispersal rates of cane toads at an invasion front compared to an already-colonized location
Publisher: Springer Science and Business Media LLC
Date: 11-04-2017
Reid's paradox revisited: The evolution of dispersal kernels during range expansion
Publisher: University of Chicago Press
Date: 07-2008
DOI: 10.1086/588255
Abstract: Current approaches to modeling range advance assume that the distribution describing dispersal distances in the population (the "dispersal kernel") is a static entity. We argue here that dispersal kernels are in fact highly dynamic during periods of range advance because density effects and spatial assortment by dispersal ability ("spatial selection") drive the evolution of increased dispersal on the expanding front. Using a spatially explicit in idual-based model, we demonstrate this effect under a wide variety of population growth rates and dispersal costs. We then test the possibility of an evolved shift in dispersal kernels by measuring dispersal rates in in idual cane toads (Bufo marinus) from invasive populations in Australia (historically, toads advanced their range at 10 km/year, but now they achieve >55 km/year in the northern part of their range). Under a common-garden design, we found a steady increase in dispersal tendency with distance from the invasion origin. Dispersal kernels on the invading front were less kurtotic and less skewed than those from origin populations. Thus, toads have increased their rate of range expansion partly through increased dispersal on the expanding front. For accurate long-range forecasts of range advance, we need to take into account the potential for dispersal kernels to be evolutionarily dynamic.
The straight and narrow path: the evolution of straight-line dispersal at a cane toad invasion front
Publisher: The Royal Society
Date: 22-11-2014
Abstract: At the edge of a biological invasion, evolutionary processes (spatial sorting, natural selection) often drive increases in dispersal. Although numerous traits influence an in idual's displacement (e.g. speed, stamina), one of the most important is path straightness. A straight (i.e. highly correlated) path strongly enhances overall dispersal rate relative to time and energetic cost. Thus, we predict that, if path straightness has a genetic basis, organisms in the invasion vanguard will exhibit straighter paths than those following behind. Our studies on invasive cane toads ( Rhinella marina ) in tropical Australia clearly support this prediction. Radio-tracking of field-collected toads at a single site showed that path straightness steadily decreased over the first 10 years post-invasion. Consistent with an evolved (genetic) basis to that behavioural shift, path straightness of toads reared under common garden conditions varied according to the location of their parents' origin. Offspring produced by toads from the invasion vanguard followed straighter paths than did those produced by parents from long-established populations. At the in idual level, offspring exhibited similar path straightness to their parents. The dramatic acceleration of the cane toad invasion through tropical Australia has been driven, in part, by the evolution of a behavioural tendency towards dispersing in a straight line.
Cane toads (Rhinella marina) rely on water access, not drought tolerance, to invade xeric Australian environments
Publisher: Springer Science and Business Media LLC
Date: 08-12-2019
DOI: 10.1007/S00442-018-4321-1
Abstract: The invasion of habitats with novel environmental challenges may require physiological tolerances not seen in conspecifics from the native range. We used a combination of field and laboratory-based experiments to assess physiological tolerance to limited water access at four sites distributed across the historical invasion path of cane toads (Rhinella marina) in Australia that, from east to west, alternated between mesic and seasonally xeric habitats. Toads from all locations were well hydrated at the time of capture. However, experimental dehydration caused greater mass loss, higher plasma osmolality, and inhibition of lytic ability in toads from xeric compared to mesic locations. These results suggest somewhat surprisingly that toads from xeric environments are physiologically more vulnerable to water loss. In contrast, bactericidal ability was not sensitive to hydric state and was greater in toads from eastern (long-colonized) areas. Similar patterns in lytic ability in hydrated toads and agglutination ability in wild toads suggest that toads along the invasion front face a tradeoff between enhanced dispersal ability and physiological responses to dehydration. The ability of this invasive species to spread into drier environments may be underpinned by a combination of phenotypic plasticity and evolved (heritable) traits.
First line of defence
Publisher: Elsevier BV
Date: 04-2021
Reproductive ecology of a tropical natricine snake, Tropidonophis mairii (Colubridae)
Publisher: Wiley
Date: 09-2002
Colonization history affects heating rates of invasive cane toads
Publisher: Springer Science and Business Media LLC
Date: 28-07-2020
DOI: 10.1038/S41598-020-69529-3
Abstract: Amphibians in hot climates may be able to avoid high temperatures by controlling their rates of heating. In northern Australia, invasive cane toads ( Rhinella marina ) experience hot dry conditions in newly-colonized (western) sites but milder conditions in longer-occupied (eastern) sites. Under standardized conditions, toads from western sites heated less rapidly than did conspecifics from an eastern site. The availability of free water slowed heating rates of eastern but not western toads. Thus, the colonization of climatically extreme sites has been accompanied by a rapid shift in the toads’ ability to remain cool under hot conditions, even when free water is not available.
It is lonely at the front: contrasting evolutionary trajectories in male and female invaders
Publisher: The Royal Society
Date: 12-2016
DOI: 10.1098/RSOS.160687
Abstract: Invasive species often exhibit rapid evolutionary changes, and can provide powerful insights into the selective forces shaping phenotypic traits that influence dispersal rates and/or sexual interactions. Invasions also may modify sexual dimorphism. We measured relative lengths of forelimbs and hindlimbs of more than 3000 field-caught adult cane toads ( Rhinella marina ) from 67 sites in Hawai'i and Australia (1–80 years post-colonization), along with 489 captive-bred in iduals from multiple Australian sites raised in a ‘common garden’ (to examine heritability and reduce environmental influences on morphology). As cane toads spread from east to west across Australia, the ancestral condition (long limbs, especially in males) was modified. Limb length relative to body size was first reduced (perhaps owing to natural selection on locomotor ability), but then increased again (perhaps owing to spatial sorting) in the invasion vanguard. In contrast, the sex disparity in relative limb length has progressively decreased during the toads' Australian invasion. Offspring reared in a common environment exhibited similar geographical ergences in morphology as did wild-caught animals, suggesting a genetic basis to the changes. Limb dimensions showed significant heritability (2–17%), consistent with the possibility of an evolved response. Cane toad populations thus have undergone a major shift in sexual dimorphism in relative limb lengths during their brief (81 years) spread through tropical Australia.
Maternal nest-site choice and offspring fitness in a tropical snake (Tropidonophis mairii, Colubridae)
Publisher: Wiley
Date: 06-2004
DOI: 10.1890/03-0107
Knowledge and Awareness of CT Radiation Dose and Risk Among Patients
Publisher: SAGE Publications
Date: 17-05-2018
Abstract: The study aims to assess the level of patients’ awareness and knowledge regarding radiation and dosage along with the associated risks from computed tomography (CT) scan. This cross-sectional study used questionnaires, which were distributed to the diagnostic imaging departments of six large local hospitals in Jordan between September 2014 and March 2015. A total of 600 patients completed the questionnaire, out of which, 52.33% of respondents were female and 47.6% male. The findings show insignificant effects of gender on patient’s knowledge ( P = .596) and significant effect of employment and profession on positive scores ( P = .000). Similarly, no statistical differences were found between gender and correct answers ( P = .707). This cohort of patients demonstrated a lack of awareness and knowledge about the use of ionizing radiation for diagnostic imaging. Thus, there may exist a similar lack of information that will require imaging professionals to raise patients’ awareness and offer them the appropriate information.
Identifying the time scale of synchronous movement: a study on tropical snakes
Publisher: Springer Science and Business Media LLC
Date: 04-05-2015
Immune response varies with rate of dispersal in invasive cane toads (Rhinella marina)
Publisher: Public Library of Science (PLoS)
Date: 17-06-2014
Why do most tropical animals reproduce seasonally? Testing hypotheses on an Australian snake
Publisher: Wiley
Date: 2006
DOI: 10.1890/04-1882
Abstract: Most species reproduce seasonally, even in the tropics where activity occurs year-round. Squamate reptiles provide ideal model organisms to clarify the ultimate (adaptive) reasons for the restriction of reproduction to specific times of year. Females of almost all temperate-zone reptile species produce their eggs or offspring in the warmest time of the year, thereby synchronizing embryogenesis with high ambient temperatures. However, although tropical reptiles are freed from this thermal constraint, most do not reproduce year-round. Seasonal reproduction in tropical reptiles might be driven by biotic factors (e.g., peak periods of predation on eggs or hatchlings, or food for hatchlings) or abiotic factors (e.g., seasonal availability of suitably moist incubation conditions). Keelback snakes (Tropidonophis mairii, Colubridae) in tropical Australia reproduce from April to November, but with a major peak in May-June. Our field studies falsify hypotheses that invoke biotic factors as explanations for this pattern: the timing of nesting does not minimize predation on eggs, nor maximize food availability or survival rates for hatchlings. Instead, our data implicate abiotic factors: female keelbacks nest most intensely soon after the cessation of monsoonal rains when soils are moist enough to sustain optimal embryogenesis (wetter nests produce larger hatchlings, that are more likely to survive) but are unlikely to become waterlogged (which is lethal to eggs). Thus, abiotic factors may favor seasonal reproduction in tropical as well as temperate-zone animals.
Effects of intense wildfires on the nesting ecology of oviparous montane lizards
Publisher: Wiley
Date: 08-08-2016
DOI: 10.1111/AEC.12362
Predator behaviour and morphology mediates the impact of an invasive species: Cane toads and death adders in Australia
Publisher: Wiley
Date: 2010
Is developmental plasticity triggered by DNA methylation changes in the invasive cane toad (Rhinella marina)?
Publisher: Cold Spring Harbor Laboratory
Date: 26-10-2023
Athletic anurans: the impact of morphology, ecology and evolution on climbing ability in invasive cane toads
Publisher: Oxford University Press (OUP)
Date: 11-06-2016
DOI: 10.1111/BIJ.12827
High infection intensities, but negligible fitness costs, suggest tolerance of gastrointestinal nematodes in a tropical snake
Publisher: Wiley
Date: 25-03-2015
DOI: 10.1111/AEC.12235
Organochlorine contaminant concentrations in eggs and their relationship to body size, and clutch characteristics of the female common snapping turtle (Chelydra serpentina serpentina) in lake Ontario, Canada
Publisher: Springer Science and Business Media LLC
Date: 07-1994
DOI: 10.1007/BF00203891
The causes and ecological correlates of head scale asymmetry and fragmentation in a tropical snake
Publisher: Springer Science and Business Media LLC
Date: 12-09-2017
DOI: 10.1038/S41598-017-11768-Y
Abstract: The challenge of identifying the proximate causes and ecological consequences of phenotypic variation can be facilitated by studying traits that are usually but not always bilaterally symmetrical deviations from symmetry likely reflect disrupted embryogenesis. Based on a 19-year mark-recapture study of slatey-grey snakes ( Stegonotus cucullatus ) in tropical Australia, and incubation of eggs, we document developmental and ecological correlates of two morphological traits: asymmetry and fragmentation of head scales. Asymmetry was directional (more scales on the left side) and was higher in in iduals with lower heterozygosity, but was not heritable. In contrast, fragmentation was heritable and was higher in females than males. Both scale asymmetry and fragmentation were increased by rapid embryogenesis but were not affected by hydric conditions during incubation. Snakes with asymmetry and fragmentation exhibited slightly lower survival and increased (sex-specific) movements, and females with more scale fragmentation produced smaller eggs. Counterintuitively, snakes with more asymmetry had higher growth rates (possibly reflecting trade-offs with other traits), and snakes with more fragmentation had fewer parasites (possibly due to lower feeding rates). Our data paint an unusually detailed picture of the complex genetic and environmental factors that, by disrupting early embryonic development, generate variations in morphology that have detectable correlations with ecological performance.
Survival of the feces: Does a nematode lungworm adaptively manipulate the behavior of its cane toad host?
Publisher: Wiley
Date: 15-04-2018
DOI: 10.1002/ECE3.3870
The thermal dependency of locomotor performance evolves rapidly within an invasive species
Publisher: Wiley
Date: 02-04-2018
DOI: 10.1002/ECE3.3996
Does foraging mode influence sensory modalities for prey detection in male and female filesnakes, Acrochordus arafurae?
Publisher: Elsevier BV
Date: 09-2005
Rapid shifts in dispersal behavior on an expanding range edge Tom
Publisher: Proceedings of the National Academy of Sciences
Date: 29-07-2013
Abstract: Dispersal biology at an invasion front differs from that of populations within the range core, because novel evolutionary and ecological processes come into play in the nonequilibrium conditions at expanding range edges. In a world where species’ range limits are changing rapidly, we need to understand how in iduals disperse at an invasion front. We analyzed an extensive dataset from radio-tracking invasive cane toads ( Rhinella marina ) over the first 8 y since they arrived at a site in tropical Australia. Movement patterns of toads in the invasion vanguard differed from those of in iduals in the same area postcolonization. Our model discriminated enc ed versus dispersive phases within each toad’s movements and demonstrated that pioneer toads spent longer periods in dispersive mode and displayed longer, more directed movements while they were in dispersive mode. These analyses predict that overall displacement per year is more than twice as far for toads at the invasion front compared with those tracked a few years later at the same site. Studies on established populations (or even those a few years postestablishment) thus may massively underestimate dispersal rates at the leading edge of an expanding population. This, in turn, will cause us to underpredict the rates at which invasive organisms move into new territory and at which native taxa can expand into newly available habitat under climate change.
Toads in the backyard: why do invasive cane toads (Rhinella marina) prefer buildings to bushland?
Publisher: Wiley
Date: 16-02-2016
Global, regional, and national burden of Alzheimer's disease and other dementias, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016
Publisher: Elsevier BV
Date: 2019
Behavioural responses of reptile predators to invasive cane toads in tropical Australia
Publisher: Wiley
Date: 11-2014
DOI: 10.1111/AEC.12102
Laid-back invaders: Cane toads (Rhinella marina) down-regulate their stress responses as they colonize a harsh climate
Publisher: Elsevier BV
Date: 12-2020
Frequency-dependent Batesian mimicry maintains colour polymorphism in a sea snake population
Publisher: Springer Science and Business Media LLC
Date: 18-03-2022
DOI: 10.1038/S41598-022-08639-6
Abstract: Evolutionary theory suggests that polymorphic traits can be maintained within a single population only under specific conditions, such as negative frequency-dependent selection or heterozygote advantage. Non-venomous turtle-headed sea snakes ( Emydocephalus annulatus ) living in shallow bays near Noumea in New Caledonia exhibit three colour morphs: black, black-and-white banded, and an intermediate (grey-banded) morph that darkens with age. We recorded morph frequencies during 18 consecutive years of surveys, and found that the numbers of recruits (neonates plus immigrants) belonging to each morph increased in years when that morph was unusually rare in the population, and decreased when that morph was unusually common. Thus, morph frequencies are maintained by negative frequency-dependent selection. We interpret the situation as Batesian mimicry of highly venomous sea snakes ( Aipysurus, Hydrophis, Laticauda ) that occur in the same bays, and range in colour from black-and-white banded to grey-banded. Consistent with the idea that mimicry may protect snakes from attack by large fish and sea eagles, behavioural studies have shown that smaller fish species in these bays flee from banded snakes but attack black in iduals. As predicted by theory, mimetic (banded) morphs are less common than the cryptically-coloured melanic morph.
Thin-skinned invaders: geographic variation in the structure of the skin among populations of cane toads (Rhinella marina)
Publisher: Oxford University Press (OUP)
Date: 15-09-2020
DOI: 10.1093/BIOLINNEAN/BLAA128
Abstract: The structure of the skin may evolve rapidly during a biological invasion, for two reasons. First, novel abiotic challenges such as hydric conditions may modify selection of traits (such as skin thickness) that determine rates of evaporative water loss. Second, invaders might benefit from enhanced rates of dispersal, with locomotion possibly facilitated by thinner (and hence more flexible) skin. We quantified thickness of layers of the skin in cane toads (Rhinella marina) from the native range (Brazil), a stepping-stone population (Hawaii), and the invaded range in Australia. Overall, the skin is thinner in cane toads in Australia than in the native range, consistent with selection on mobility. However, layers that regulate water exchange (epidermal stratum corneum and dermal ground substance layer) are thicker in Australia, retarding water loss in hot dry conditions. Within Australia, epidermal thickness increased as the toads colonized more arid regions, but then decreased in the arid Kimberley region. That curvilinearity might reflect spatial sorting, whereby mobile (thin-skinned) in iduals dominate the invasion front or the toads’ restriction to moist sites in this arid landscape may reduce the importance of water-conservation. Further work is needed to clarify the roles of adaptation versus phenotypic plasticity in generating the strong geographic variation in skin structure among populations of cane toads.
Invasive Cane Toads: Social Facilitation Depends upon an Individual’s Personality
Publisher: Public Library of Science (PLoS)
Date: 17-07-2014
Global, Regional, and National Cancer Incidence, Mortality, Years of Life Lost, Years Lived With Disability, and Disability-Adjusted Life-Years for 29 Cancer Groups, 1990 to 2017
Publisher: American Medical Association (AMA)
Date: 12-2019
Mathematical modelling of spatial sorting and evolution in a host–parasite system
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.JTBI.2015.06.027
Abstract: There have been numerous empirical and agent-based modelling studies on the spatial self-structuring of traits, particularly in regard to dispersal ability (termed spatial sorting) of cane toads in northern Australia, but few mathematical modelling studies. In this study, we formulate a reaction-diffusion based partial-integro-differential equation model based on an earlier model by Bouin et al. (2012) to examine this spatial self-structuring of traits in both a cane toad population and lungworm parasite population, which evolves with the cane toad population. In particular, the traits we focus on are dispersal ability for the cane toad population and both prepatent period and larval size for the lungworm parasite population. Apart from the spatial self-structuring of these traits, our results confirm a number of observations made in empirical and agent-based studies particularly, that there is a noticeable lag between the host and parasite population which is critically dependent on the parasite functional response to host densities, that older populations regress back to lower dispersal speeds and that spatial sorting can still occur with a disadvantage in reproductivity and/or survival in more motile in iduals. Moreover, we find that such a disadvantage in reproductivity and/or survival is unlikely to be large if spatial sorting is to have a noticeable effect on the rate of range expansion, as it has been observed to have over the last 60 years in northern Australia.
The effects of a nematode lungworm (Rhabdias hylae) on its natural and invasive anuran hosts
Publisher: American Society of Parasitologists
Date: 06-2015
DOI: 10.1645/14-657.1
Abstract: Biological invasions can bring both the invader and native taxa into contact with novel parasites. As cane toads ( Rhinella marina ) have spread through Australia, they have encountered lungworms (Rhabdias hylae) that occur in native frogs. Field surveys suggest that these lungworms have not host-switched to toads. In our laboratory studies, R. hylae infected cane toads as readily as it infected native frogs, but failed to reach the lungs of the novel host (i.e., were killed by the toads' immune response). Plausibly, then, R. hylae might reduce the viability both of their native hosts (frogs, that can exhibit high parasite burdens) and cane toads (that must deal with infective larvae traveling through the host body). Our laboratory trials suggest, however, that the impacts of the parasite on infected anuran hosts (both frogs and toads) were minimal, with no significant decrements to host survival, activity, growth, or locomotor performance. Ironically, the lack of impact of the parasite on its native hosts appears to be an outcome of co-evolution (frogs tolerate the lungworm), whereas the lack of impact on the novel host is due to a lack of co-evolution (toads can recognize and eliminate the lungworm).
Alcohol use and burden for 195 countries and territories, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016
Publisher: Elsevier BV
Date: 09-2018
Rain, prey and predators: Climatically driven shifts in frog abundance modify reproductive allometry in a tropical snake
Publisher: Springer Science and Business Media LLC
Date: 28-08-2007
DOI: 10.1007/S00442-007-0842-8
Abstract: To predict the impacts of climate change on animal populations, we need long-term data sets on the effects of annual climatic variation on the demographic traits (growth, survival, reproductive output) that determine population viability. One frequent complication is that fecundity also depends upon maternal body size, a trait that often spans a wide range within a single population. During an eight-year field study, we measured annual variation in weather conditions, frog abundance and snake reproduction on a floodplain in the Australian wet-dry tropics. Frog numbers varied considerably from year to year, and were highest in years with hotter wetter conditions during the monsoonal season ("wet season"). Mean maternal body sizes, egg sizes and post-partum maternal body conditions of frog-eating snakes (keelback, Tropidonophis mairii, Colubridae) showed no significant annual variation over this period, but mean clutch sizes were higher in years with higher prey abundance. Larger females were more sensitive to frog abundance in this respect than were smaller conspecifics, so that the rate at which fecundity increased with body size varied among years, and was highest when prey availability was greatest. Thus, the link between female body size and reproductive output varied among years, with climatic factors modifying the relative reproductive rates of larger (older) versus smaller (younger) animals within the keelback population.
Invader impact clarifies the roles of top‐down and bottom‐up effects on tropical snake populations
Publisher: Wiley
Date: 08-02-2013
Erratum: Measuring progress and projecting attainment on the basis of past trends of the health-related Sustainable Development Goals in 188 countries: an analysis from the Global Burden of Disease Study 2016 (The Lancet (2017) 390(10100) (1423–1459) (S014067361732336X) (10.1016/S0140-6736(17)32336-X))
Publisher: Elsevier BV
Date: 10-2017
Hatchling Australian freshwater crocodiles rapidly learn to avoid toxic invasive cane toads
Publisher: Brill
Date: 2011
Global, regional, and country-specific lifetime risks of stroke, 1990 and 2016
Publisher: Massachusetts Medical Society
Date: 20-12-2018
Genetic analysis of the mating system and opportunity for sexual selection in northern water snakes (Nerodia sipedon)
Publisher: Oxford University Press (OUP)
Date: 11-2002
Sexual abstinence and the cost of reproduction in adult male water snakes, Nerodia sipedon
Publisher: Wiley
Date: 16-01-2004
Male reproductive success and sexual selection in northern water snakes determined by microsatellite DNA analysis
Publisher: Oxford University Press (OUP)
Date: 11-2002
Predation on toxic cane toads (Bufo marinus) may imperil bluetongue lizards (Tiliqua scincoides intermedia, Scincidae) in tropical Australia
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/WR09170
Abstract: Context. Detecting ecological impacts of invasive species can be extremely difficult. Even major population declines may be undetectable without extensive long-term data if the affected taxon is rare and/or difficult to census, and exhibits stochastic variation in abundance as a result of other factors. Our data suggest such a situation in an iconic Australian reptile species, the bluetongue lizard. Originally restricted to Central and South America, cane toads (Bufo marinus) are rapidly spreading through tropical Australia. Most native predators have no evolutionary history of exposure to the toads’ distinctive chemical defences (bufadienolides), and many varanid lizards, elapid snakes, crocodiles and marsupials have been killed when they have attempted to consume toads. Aims. Scincid lizards have not been considered vulnerable to toad invasion however, one lineage (the bluetongues, genus Tiliqua) consists of large omnivores that may be affected. Our field and laboratory research aimed to elucidate this concern. Methods. Nightly surveys for bluetongue lizards (Tiliqua scincoides intermedia) and cane toads were conducted along two adjacent roadways on the Adelaide River floodplain of the Northern Territory. Scent discrimination trials in the laboratory assessed lizard responses to chemical cues from three food types (native frogs, cane toads and ‘preferred foods’) by counting tongue-flicks and biting elicited by cotton swabs. A subset of lizards was presented with live toads. Key results. Numbers of bluetongues encountered during standardised field surveys in the Darwin region declined soon after toads arrived, and we have not recorded a single lizard for the last 20 months. In the laboratory, foraging responses of bluetongues were as intense to cane-toad scent as to the scent of native frogs, and many of the lizards we tested attempted to consume toads, and were poisoned as a result. Conclusions and implications. The population decline of bluetongues in this region appears to have been the direct result of fatal ingestion of toxic cane toads. Our studies thus add a scincid lizard species to the list of native Australian predators imperilled by cane-toad invasion, and point to the difficulty of detecting invader impact even for an iconic species in a system subject to detailed survey work.
Divergence in life-history traits among three adjoining populations of the sea snake Emydocephalus annulatus (Hydrophiinae, Elapidae)
Publisher: Springer Science and Business Media LLC
Date: 24-03-2022
DOI: 10.1038/S41598-022-09130-Y
Abstract: Life-history traits such as rates of growth, survival and reproduction can vary though time within a single population, or through space among populations, due to abiotically-driven changes in resource availability. In terrestrial reptiles, parameters such as temperature and rainfall generate variation in life-histories—but other parameters likely are more important in marine systems. We studied three populations of sea snakes ( Emydocephalus annulatus ) in adjacent bays in the IndoPacific archipelago of New Caledonia. The extreme philopatry of in idual snakes allows us to unambiguously allocate each animal to one of the three populations. Although water temperatures and rainfall do not differ over this small scale, one site experiences more intense winds, restricting opportunities for foraging. Our 18-year mark-recapture dataset ( 1,200 snakes, 2,400 captures) reveals significant ergence among populations in life-history traits. Survival rates and population densities were similar among sites, but snakes at the most wind-exposed site (Anse Vata) exhibited lower body condition, slower growth, less frequent production of litters, and smaller litters. Weather-driven variation in feeding rates thus may affect life-history traits of marine snakes as well as their terrestrial counterparts, but driven by different parameters (e.g., wind exposure rather than variation in temperatures or rainfall).
The uneasy coexistence between Carpet Pythons and Cane Toads
Publisher: Royal Zoological Society of New South Wales
Date: 11-11-2020
DOI: 10.7882/AZ.2020.042
Abstract: We describe a case of a free-ranging Carpet Python Morelia spilota consuming a toxic Cane Toad Rhinella marina, and dying as a result. Such an encounter would not be surprising at the toad invasion front, where predators first confront this novel prey type. However, the encounter we describe occurred at a site near Darwin where toads have been present for fifteen years. Other reports suggest that the behaviour we observed occurs across the snake’s range. Lethal ingestion of toads has been suggested to threaten the viability of populations of Carpet Pythons, but paradoxically, our surveys at this site reveal a twofold increase in abundance of Carpet Pythons since the arrival of toads. Toad invasion likely has favoured pythons by reducing the abundance of large monitor lizards, that are both predators and competitors of Carpet Pythons. That advantage has outweighed occasional cases where a snake is fatally poisoned by consuming a toad. Thus, the overall impact of Cane Toads on Carpet Pythons (and likely, other predator species) is a balance between direct costs and indirect benefits. Negative impacts on in iduals may not necessarily translate to a negative impact on the species.
Global Cardiovascular and Renal Outcomes of Reduced GFR
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 13-04-2017
Abstract: The burden of premature death and health loss from ESRD is well described. Less is known regarding the burden of cardiovascular disease attributable to reduced GFR. We estimated the prevalence of reduced GFR categories 3, 4, and 5 (not on RRT) for 188 countries at six time points from 1990 to 2013. Relative risks of cardiovascular outcomes by three categories of reduced GFR were calculated by pooled random effects meta-analysis. Results are presented as deaths for outcomes of cardiovascular disease and ESRD and as disability-adjusted life years for outcomes of cardiovascular disease, GFR categories 3, 4, and 5, and ESRD. In 2013, reduced GFR was associated with 4% of deaths worldwide, or 2.2 million deaths (95% uncertainty interval [95% UI], 2.0 to 2.4 million). More than half of these attributable deaths were cardiovascular deaths (1.2 million 95% UI, 1.1 to 1.4 million), whereas 0.96 million (95% UI, 0.81 to 1.0 million) were ESRD-related deaths. Compared with metabolic risk factors, reduced GFR ranked below high systolic BP, high body mass index, and high fasting plasma glucose, and similarly with high total cholesterol as a risk factor for disability-adjusted life years in both developed and developing world regions. In conclusion, by 2013, cardiovascular deaths attributed to reduced GFR outnumbered ESRD deaths throughout the world. Studies are needed to evaluate the benefit of early detection of CKD and treatment to decrease these deaths.
Adapting to the unpredictable: reproductive biology of vertebrates in the Australian wet-dry tropics
Publisher: The Royal Society
Date: 18-07-2008
Abstract: In the wet–dry tropics of northern Australia, temperatures are high and stable year-round but monsoonal rainfall is highly seasonal and variable both annually and spatially. Many features of reproduction in vertebrates of this region may be adaptations to dealing with this unpredictable variation in precipitation, notably by (i) using direct proximate (rainfall-affected) cues to synchronize the timing and extent of breeding with rainfall events, (ii) placing the eggs or offspring in conditions where they will be buffered from rainfall extremes, and (iii) evolving developmental plasticity, such that the timing and trajectory of embryonic differentiation flexibly respond to local conditions. For ex le, organisms as erse as snakes ( Liasis fuscus , Acrochordus arafurae ), crocodiles ( Crocodylus porosus ), birds ( Anseranas semipalmata ) and wallabies ( Macropus agilis ) show extreme annual variation in reproductive rates, linked to stochastic variation in wet season rainfall. The seasonal timing of initiation and cessation of breeding in snakes ( Tropidonophis mairii ) and rats ( Rattus colletti ) also varies among years, depending upon precipitation. An alternative adaptive route is to buffer the effects of rainfall variability on offspring by parental care (including viviparity) or by judicious selection of nest sites in oviparous taxa without parental care. A third type of adaptive response involves flexible embryonic responses (including embryonic diapause, facultative hatching and temperature-dependent sex determination) to incubation conditions, as seen in squamates, crocodilians and turtles. Such flexibility fine-tunes developmental rates and trajectories to conditions–-especially, rainfall patterns–-that are not predictable at the time of oviposition.
Directional dispersal has not evolved during the cane toad invasion
Publisher: Wiley
Date: 12-01-2015
Ecological immunization: In situ training of free-ranging predatory lizards reduces their vulnerability to invasive toxic prey
Publisher: The Royal Society
Date: 2016
Abstract: In Australia, large native predators are fatally poisoned when they ingest invasive cane toads ( Rhinella marina ). As a result, the spread of cane toads has caused catastrophic population declines in these predators. Immediately prior to the arrival of toads at a floodplain in the Kimberley region, we induced conditioned taste aversion in free-ranging varanid lizards ( Varanus panoptes ), by offering them small cane toads. By the end of the 18-month study, only one of 31 untrained lizards had survived longer than 110 days, compared to more than half (nine of 16) of trained lizards the maximum known survival of a trained lizard in the presence of toads was 482 days. In situ aversion training (releasing small toads in advance of the main invasion front) offers a logistically simple and feasible way to buffer the impact of invasive toads on apex predators.
Global, Regional, and National Cancer Incidence, Mortality, Years of Life Lost, Years Lived With Disability, and Disability-Adjusted Life-years for 32 Cancer Groups, 1990 to 2015
Publisher: American Medical Association (AMA)
Date: 04-2017
Parasites and pathogens lag behind their host during periods of host range advance
Publisher: Wiley
Date: 03-2010
DOI: 10.1890/09-0530.1
Abstract: The process of rapid range expansion (as seen in many invasive species, and in taxa responding to climate change) may substantially disrupt host-parasite dynamics. Parasites and pathogens can have strong regulatory effects on their host population and, in doing so, exert selection pressure on host life history. We construct a simple in idual-based model of host-parasite dynamics during range expansion. This model shows that the parasites and pathogens of a range-expanding host are likely to be absent from the host's invasion front, because stochastic events (serial founder events) in low-density frontal populations result in local extinctions or transmission failure of the parasite athogen and, hence, a preponderance of uninfected hosts in the invasion vanguard. This pattern is true for both density-dependent and density-independent transmission rates, although it is exacerbated in the case of density-dependent transmission because, in this case, transmission rates also decline on the front. Data from field surveys on the prevalence of lungworms (Rhabdias pseudosphaerocephala) in invasive cane toads (Bufo marinus) support these predictions, in showing that toads in newly invaded areas of tropical Australia lack the parasite, which only arrives 1-3 years after the toads themselves. The resultant "honeymoon phase" immediately post-invasion, when in iduals in the invasion-front population are virtually pathogen-free, may lead to altered host population dynamics on the invasion front, causing, for ex le, high densities in invasion-front populations, followed by a decline in numbers as parasites and pathogens arrive and begin to reduce host viability. The honeymoon phase may ultimately impact the evolution of life-history investment strategies in both host and parasite on the invasion vanguard, as hosts are released from immune challenges and parasites continuously expand into a favorable and unoccupied niche.
The enduring toxicity of road-killed cane toads (Rhinella marina)
Publisher: Springer Science and Business Media LLC
Date: 10-06-2011
Geographic divergence in dispersal-related behaviour in cane toads from range-front versus range-core populations in Australia
Publisher: Springer Science and Business Media LLC
Date: 21-01-2017
Like mother, like daughter: inheritance of nest-site location in snakes
Publisher: The Royal Society
Date: 06-02-2007
Abstract: A trait can be passed from parents to offspring even if it has no genetic basis. For ex le, if daughters return to reproduce at the same sites where they were hatched themselves, nest-site location is consistent within matrilineages. Most cases of natal homing (nest-site philopatry) across generations have been inferred from molecular evidence rather than directly demonstrated, and involve species with low dispersal abilities. However, some animals disperse long distances but then return to their own place of birth to reproduce, based on cues imprinted early in their own development. Our field studies on tropical natricine snakes ( Tropidonophis mairii , Colubridae) show that when they are ready to nest, females return to the sites where their mothers were captured pre-nesting, and where they themselves were released as hatchlings.
Identifying optimal barriers to halt the invasion of cane toads Rhinella marina in arid Australia
Publisher: Wiley
Date: 12-12-2013
The spatial ecology of cane toads (Bufo marinus) in tropical Australia: Why do metamorph toads stay near the water?
Publisher: Wiley
Date: 04-07-2008
Road transect surveys do not reveal any consistent effects of a toxic invasive species on tropical reptiles
Publisher: Springer Science and Business Media LLC
Date: 21-10-2013
In an arms race between host and parasite, a lungworm's ability to infect a toad is determined by host susceptibility not parasite preference
Publisher: The Royal Society
Date: 03-2022
Abstract: Evolutionary arms races can alter both parasite infectivity and host resistance, and it is difficult to separate the effects of these twin determinants of infection outcomes. We used a co-introduced, invasive host–parasite system (the lungworm Rhabdias pseudosphaerocephala and cane toads Rhinella marina ), where rapid adaptation and dispersal have led to population differences in infection resistance. We quantified behavioural responses of parasite larvae to skin-chemical cues of toads from different invasive populations, and rates at which juvenile hosts became infected following standardized exposure to lungworms. Chemical cues from toad skin altered host-seeking behaviour by parasites, similarly among populations. The number of infection attempts (parasite larvae entering the host's body) also did not differ between populations, but rates of successful infection (establishment of adult worm in host lungs) were higher for range-edge toads than for range-core conspecifics. Thus, lower resistance to parasite infection in range-edge juvenile toads appears to be due to less effective immune defences of the host rather than differential behavioural responses of the parasite. In this ongoing host–parasite arms race, changing outcomes appear to be driven by shifts in host immunocompetence.
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
Evolutionarily accelerated invasions: the rate of dispersal evolves upwards during the range advance of cane toads
Publisher: Wiley
Date: 07-10-2010
DOI: 10.1111/J.1420-9101.2010.02118.X
Abstract: Human activities are changing habitats and climates and causing species' ranges to shift. Range expansion brings into play a set of powerful evolutionary forces at the expanding range edge that act to increase dispersal rates. One likely consequence of these forces is accelerating rates of range advance because of evolved increases in dispersal on the range edge. In northern Australia, cane toads have increased their rate of spread fivefold in the last 70 years. Our breeding trials with toads from populations spanning the species' invasion history in Australia suggest a genetic basis to dispersal rates and interpopulation genetic variation in such rates. Toads whose parents were from the expanding range front dispersed faster than toads whose parents were from the core of the range. This difference reflects patterns found in their field-collected mothers and fathers and points to heritable variance in the traits that have accelerated the toads' rate of invasion across tropical Australia over recent decades. Taken together with demonstrated spatial assortment by dispersal ability occurring on the expanding front, these results point firmly to ongoing evolution as a driving force in the accelerated expansion of toads across northern Australia.
Infection by the lungwormRhabdias pseudosphaerocephalaaffects the expression of immune-related microRNAs by its co-evolved host, the cane toadRhinella marina
Publisher: Cold Spring Harbor Laboratory
Date: 22-06-2023
DOI: 10.1101/2023.06.19.545515
Abstract: Parasites may suppress the immune function of an infected host using microRNAs (miRNAs) to prevent protein production. Nonetheless, little is known about the ersity of miRNAs and their mode(s) of action. In this study, we investigated the effects of infection by a parasitic lungworm ( Rhabdias pseudosphaerocephala ) on miRNA and mRNA expression of its host, the invasive cane toad ( Rhinella marina ). We compared miRNA and mRNA expression in naïve toads that had never been infected by lungworms to toads that were infected with lungworms for the first time in their lives, and to toads that were infected the second time in their lives (i.e., had two consecutive infections). In total, we identified 434 known miRNAs and 106 potential novel miRNAs. Compared to uninfected toads, infected animals upregulated five (single-infection treatment) or four (multiple-infection treatment) miRNAs. Seven of these differentially expressed miRNAs were associated with gene pathways related to the immune response, potentially reflecting immunosuppression of cane toads by their parasites. Infected hosts did not respond with substantial mRNA transcription, with only one differentially expressed gene between control and single-infection hosts. Our study suggests that miRNA-mediated interactions may play a role in mediating the interaction between the parasite and its host. Our findings clarify the role of miRNAs in host-parasite interactions, in a system in which an ongoing range expansion by the host has generated substantial ergence in host-parasite interactions.
Niche partitioning within a population of sea snakes is constrained by ambient thermal homogeneity and small prey size
Publisher: Oxford University Press (OUP)
Date: 10-01-2020
DOI: 10.1093/BIOLINNEAN/BLZ206
Abstract: In many populations of terrestrial snakes, the phenotype of an in idual (e.g. body size, sex, colour) affects its habitat use. One cause for that link is gape limitation, which can result in larger snakes eating prey that are found in different habitats. A second factor involves thermoregulatory opportunities, whereby in iduals select habitats based upon thermal conditions. These ideas predict minimal intraspecific variation in habitat use in a species that eats small prey and lives in a thermally uniform habitat, such as the sea snake Emydocephalus annulatus, which feeds on tiny fish eggs and lives in inshore coral reefs. To test that prediction, we gathered data on water depths and substrate attributes for 1475 sightings of 128 free-ranging E. annulatus in a bay near Noumea, New Caledonia. Habitat selection varied among in iduals, but with a preference for coral-dominated substrates. The body size and reproductive state of a snake affected its detectability in deep water, but overall habitat use was not linked to snake body size, colour morph, sex or pregnancy. A lack of ontogenetic shifts in habitat use allows extreme philopatry in E. annulatus, thereby reducing gene flow among populations and, potentially, delaying recolonization after local extirpation events.
Immune and environment‐driven gene expression during invasion: An eco‐immunological application of RNA‐Seq
Publisher: Wiley
Date: 09-05-2019
DOI: 10.1002/ECE3.5249
Rapid divergence of parasite infectivity and host resistance during a biological invasion
Publisher: Oxford University Press (OUP)
Date: 03-02-2021
DOI: 10.1093/BIOLINNEAN/BLAA229
Abstract: By perturbing co-evolved interactions, biological invasions provide an opportunity to study the evolution of interactions between hosts and their parasites on ecological timescales. We studied the interaction between the cane toad (Rhinella marina) and its direct-lifecycle lungworm (Rhabdias pseudosphaerocephala) that was brought from South America to Australia with the toads in 1935. Compared with infective parasite larvae from long-established (range-core) toad populations, parasite larvae from toads near the invasion front were larger, lived longer and were better able to resist exposure to toxin from the parotoid glands of toads. Experimentally, we infected the common-garden-reared progeny of toads from range-core and invasion-front populations within Australia with lungworms from both populations. Infective larvae from invasion-front (vs. range-core) populations of the parasite were more successful at entering toads (by skin penetration) and establishing infections in the lungs. Toads from invasion-front populations were less prone to infection by either type of larvae. Thus, within 84 years, parasites at an invasion front have increased infectivity, whereas hosts have increased resistance to parasite infection compared with range-core populations. Rapid evolution of traits might affect host–parasite interactions during biological invasions, generating unpredictable effects both on the invaders and on native ecosystems.
Variation in offspring sex ratios in the northern water snake (Nerodia sipedon)
Publisher: Canadian Science Publishing
Date: 1998
Reply to Lee: Spatial sorting, assortative mating, and natural selection
Publisher: Proceedings of the National Academy of Sciences
Date: 28-06-2011
A famous failure: Why were cane toads an ineffective biocontrol in Australia?
Publisher: Wiley
Date: 06-10-2020
DOI: 10.1111/CSP2.296
Communally nesting migratory birds create ecological hot-spots in Tropical Australia
Publisher: Public Library of Science (PLoS)
Date: 05-10-2016
The effects of weather conditions on dispersal behaviour of free-ranging lizards (Tiliqua, Scincidae) in tropical Australia
Publisher: Wiley
Date: 15-11-2014
Floods and famine: climate‐induced collapse of a tropical predator‐prey community
Publisher: Wiley
Date: 19-08-2015
Field experiments on foraging in free-ranging water snakes Enhydris polylepis (Homalopsinae)
Publisher: Elsevier BV
Date: 12-2004
The early toad gets the worm: Cane toads at an invasion front benefit from higher prey availability
Publisher: Wiley
Date: 29-01-2013
Abstract: In biological invasions, rates of range expansion tend to accelerate through time. What kind of benefits to more rapidly dispersing organisms might impose natural selection for faster rates of dispersal, and hence the evolution of range-edge acceleration? We can answer that question by comparing fitness-relevant ecological traits of in iduals at the invasion front compared with conspecifics in the same area a few years post-invasion. In tropical Australia, the rate of invasion by cane toads (Rhinella marina) has increased substantially over recent decades, due to shifts in heritable traits. Our data on field-collected cane toads at a recently invaded site in the Australian wet-dry tropics span a 5-year period beginning with toad arrival. Compared with conspecifics that we monitored in the same sites post-invasion, toads in the invasion vanguard exhibited higher feeding rates, larger energy stores, better body condition and faster growth. Three processes may have contributed to this pattern: (i) higher prey availability at the front (perhaps due to reduced competition from conspecifics) (ii) the lack of viability-reducing parasites and pathogens in invasion-front toads and (iii) distinctive (active, fast-growing) phenotypes of the invasion-front toads. Nutritional benefits to in iduals in the invasion vanguard (whether because of higher prey availability, or lower pathogen levels) thus may have conferred a selective advantage to accelerated dispersal in this system.
Pathology of Runting in Farmed Saltwater Crocodiles (Crocodylus porosus) in Australia
Publisher: SAGE Publications
Date: 06-01-2014
Abstract: Extremely poor growth of some in iduals within a birth cohort (runting) is a significant problem in crocodile farming. We conducted a pathological investigation to determine if infectious disease is associated with runting in farmed saltwater crocodiles ( Crocodylus porosus) and to look for evidence of other etiologies. In each of 2005 and 2007, 10 normal and 10 runt crocodiles, with an average age of 5.5 months and reared under identical conditions, were s led. Laboratory testing included postmortem histological examination of a wide variety of tissues (with quantitation of features that were noted subjectively to be different between groups) hematology serum biochemistry (total protein, albumin, globulins, total calcium, phosphorus, and iron) bacterial culture of liver and spleen (2005 only) viral culture of liver, thymus, tonsil, and spleen using primary crocodile cell lines (2007 only) and serum corticosterone (2007 only). The only evidence of infectious disease was mild cutaneous poxvirus infection in 45% of normal and 40% of runt crocodiles and rare intestinal coccidia in 5% of normal and 15% of runt crocodiles. Bacterial and viral culture did not reveal significant differences between the 2 groups. However, runt crocodiles exhibited significant ( P .05) increases in adrenocortical cell cytoplasmic vacuolation and serum corticosterone, decreased production of bone (osteoporosis), and reduced lymphoid populations in the spleen, tonsil, and thymus. Runts also exhibited moderate anemia, hypoalbuminemia, and mild hypophosphatemia. Taken together, these findings suggest an association between runting and a chronic stress response (hyperactivity of the hypothalamic-pituitary-adrenal axis).
Host defense or parasite cue: Skin secretions mediate interactions between amphibians and their parasites
Publisher: Wiley
Date: 26-06-2021
DOI: 10.1111/ELE.13832
Abstract: Amphibian skin secretions (substances produced by the hibian plus microbiota) plausibly act as a first line of defense against parasite athogen attack, but may also provide chemical cues for pathogens. To clarify the role of skin secretions in host–parasite interactions, we conducted experiments using cane toads ( Rhinella marina ) and their lungworms ( Rhabdias pseudosphaerocephala ) from the range‐core and invasion‐front of the introduced anurans’ range in Australia. Depending on the geographical area, toad skin secretions can reduce the longevity and infection success of parasite larvae, or attract lungworm larvae and enhance their infection success. These striking differences between the two regions were due both to differential responses of the larvae, and differential effects of the skin secretions. Our data suggest that skin secretions play an important role in host–parasite interactions in anurans, and that the arms race between a host and parasite can rapidly generate spatial variation in critical features of that interaction.
Department of Error
Publisher: Elsevier BV
Date: 2017
Spinal arthropathy associated with Ochrobactrum anthropi in free-ranging cane toads (Chaunus Bufo marinus) in Australia
Publisher: SAGE Publications
Date: 2008
DOI: 10.1354/VP.45-1-85
Abstract: Inflammatory or degenerative pathology involving the vertebral bodies and/or ventral intervertebral joints has been described in numerous species, both captive and free ranging, including mammals, birds, and snakes, although never in hibians. We described 15 cases of a newly recognized spinal arthropathy in adult cane toads ( Chaunus [Bufo] marinus), an invasive species in Australia. Grossly appreciable lesions consisted primarily of ventral proliferation of bone and cartilage that resulted in ankylosis. Histologic examination of the entire vertebral columns of the 15 affected toads revealed 13 toads to have lesions at multiple intervertebral sites, totalling 41 intervertebral joints with lesions. Most lesions involved bone and cartilage proliferation that resulted in fusion of the joint, with (n = 15) or without (n = 9) associated pyogranulomatous inflammation. In the remaining 17 affected joints, histologic lesions were characterized by degeneration of articular cartilage without joint fusion. In addition, in one of these joints, there was also hemorrhage and pyogranulomatous inflammation. Bacterial culture of affected joints in 9 toads and grossly normal joints in 4 control toads resulted in isolation of Ochrobactrum anthropi in 7 affected toads but in none of the controls ( P .01). We proposed an interaction between degenerative and bacterial etiologies in the pathogenesis of this condition. Invasive toads may be predisposed to this condition because of their large size increased rates of movement and, possibly, immunosuppression resulting from inhabiting a novel environment.
Effects of toe-clipping on growth, body condition, and locomotion of cane toads (Rhinella marina)
Publisher: American Society of Ichthyologists and Herpetologists (ASIH)
Date: 07-2017
DOI: 10.1643/CE-16-564
Biotic interactions mediate the influence of bird colonies on vegetation and soil chemistry at aggregation sites
Publisher: Wiley
Date: 03-01-2017
DOI: 10.1002/ECY.1642
Abstract: Colonial-nesting organisms can strongly alter the chemical and biotic conditions around their aggregation sites, with cascading impacts on other components of the ecosystem. In tropical Australia, Metallic Starlings (Aplonis metallica) nest in large colonies far above the forest canopy, in emergent trees. The ground beneath those trees is open, in stark contrast to the dense foliage all around. We surveyed the areas beneath 27 colony trees (and nearby randomly chosen trees lacking bird colonies) to quantify the birds' impacts on soil and vegetation characteristics, and to test alternative hypotheses about the proximate mechanisms responsible for the lack of live vegetation beneath colony trees. Nutrient levels were greatly elevated beneath colony trees (especially, those with larger colonies), potentially reaching levels toxic to older trees. However, seedlings thrived in the soil from beneath colony trees. The primary mechanism generating open areas beneath colony trees is disturbance by scavengers (feral pigs and native Turkeys) that are attracted in vast numbers to these nutrient hotspots. Seedlings flourished within exclosures inaccessible to vertebrate herbivores, but were rapidly consumed if unprotected. Our results contrast with previous studies of colonies of seabirds on remote islands, where a lack of large terrestrial herbivores results in bird colonies encouraging rather than eliminating vegetation in areas close to the nesting site. In our continental study system, scavengers may rapidly dilute the spatial heterogeneity generated by the massive nutrient subsidy from bird colonies.
Cane Toads on Cowpats: Commercial Livestock Production Facilitates Toad Invasion in Tropical Australia
Publisher: Public Library of Science (PLoS)
Date: 07-11-2012
Diagnostic investigation of new disease syndromes in farmed Australian saltwater crocodiles (Crocodylus porosus) reveals associations with herpesviral infection
Publisher: SAGE Publications
Date: 13-04-2016
Abstract: Since 2006, 3 new disease syndromes have emerged in farmed saltwater crocodiles ( Crocodylus porosus) in the Northern Territory of Australia. We describe the syndromes through a retrospective study of laboratory findings from 187 diagnostic cases submitted to Berrimah Veterinary Laboratories between 2005 and 2014. The first syndrome was characterized by conjunctivitis and/or pharyngitis (CP), primarily in hatchlings. Herpesviruses were isolated in primary crocodile cell culture, or were detected by PCR directly from conjunctiva or pharyngeal tissue, in 21 of 39 cases of CP (54%), compared with 9 of 64 crocodiles without the syndrome (14%, p 0.0001). Chlamydiaceae were detected by PCR in conjunctiva or pharyngeal tissue of 55% of 29 CP cases tested, and of these, 81% also contained herpesvirus. The second syndrome occurred in juveniles and growers exhibiting poor growth, and was characterized histologically by systemic lymphoid proliferation and nonsuppurative encephalitis (SLPE). Herpesviruses were isolated or detected by PCR from at least 1 internal organ in 31 of 33 SLPE cases (94%) compared with 5 of 95 crocodiles without the syndrome (5%, p 0.0001). The third syndrome, characterized by multifocal lymphohistiocytic infiltration of the dermis (LNS), occurred in 6 harvest-sized crocodiles. Herpesviruses were isolated from at least 1 skin lesion in 4 of these 6 cases. Although our study revealed strong associations between herpesvirus and the CP and SLPE syndromes, the precise nature of the role of herpesvirus, along with the pathogenesis and epidemiology of the syndromes, requires further investigation.
Immune configuration in hatchling snakes is affected by incubation moisture, and is linked to subsequent growth and survival in the field
Publisher: Wiley
Date: 26-03-2018
DOI: 10.1002/JEZ.2154
Abstract: We incubated the eggs of field-caught keelback snakes (Tropidonophis mairii) on wet versus dry substrates to explore impacts of incubation conditions on white blood cell (WBC) concentrations and differential WBC counts of hatchlings. In a second, independent study young snakes were released into the field, allowing us to explore fitness correlates of WBC profiles. Dry incubation reduced embryonic survival and hatchling body size, thus decoupling egg size from hatchling size. Incubation conditions also altered WBC profiles. Lymphocyte and azurophil counts were related to hatchling body size but not to initial egg mass, whereas heterophil counts were related to both of these traits. The egg-size effect on heterophil counts may reflect a maternal effect on offspring immune configuration. The ratio of heterophils to lymphocytes (an index of stress) was higher in hatchlings from eggs incubated on dry substrates. Snakes with higher counts of lymphocytes at hatching were more likely to be recaptured as adults (H:L an index of survival), whereas snakes with higher basophil counts exhibited more rapid growth. In summary, our experiments show that incubation moisture levels influence the immune configuration of hatchling snakes, and that variation among in iduals in WBC counts at hatching is a significant predictor of an in idual's fitness after it is released into the wild. The demonstrated link between incubation conditions and offspring fitness is likely to impose strong selection on maternal nest-site choice.
Rapid expansion of the cane toad (Bufo marinus) invasion front in tropical Australia
Publisher: Wiley
Date: 05-03-2007
Variation in size and shape of toxin glands among cane toads from native-range and invasive populations
Publisher: Springer Science and Business Media LLC
Date: 13-01-2021
DOI: 10.1038/S41598-020-80191-7
Abstract: If optimal investment in anti-predator defences depends on predation risk, invading new regions (and thus, encountering different predators) may favour shifts in that investment. Cane toads offer an ideal system to test this prediction: expensive anti-predator toxins are stored mainly in parotoid glands whose dimensions are easy to measure, and toad invasions have changed the suites of predators they encounter. Although plasticity may influence parotoid morphology, comparisons between parents and progeny revealed that gland dimensions were highly heritable. That heritability supports the plausibility of an evolved basis to variation in gland dimensions. Measurements of 3779 adult toads show that females have larger glands than males, invasive populations have larger glands than in the native-range, and that parotoid sexual size dimorphism varies strongly among invaded areas. Geographic variation in parotoid morphology may be driven by predation risk to both adult toads and offspring (provisioned with toxins by their mother), with toxins allocated to eggs exacerbating the risk of cannibalism but reducing the risk of interspecific predation. Investment into chemical defences has evolved rapidly during the cane toad’s international diaspora, consistent with the hypothesis that organisms flexibly adjust resource allocation to anti-predator tactics in response to novel challenges.
Mass mortality of native anuran tadpoles in tropical Australia due to the invasive cane toad ( Bufo marinus )
Publisher: Elsevier BV
Date: 09-2008
The cost of chemical defence
Publisher: The Royal Society
Date: 15-05-2019
Abstract: Many animals capable of deploying chemical defences are reluctant to use them, suggesting that synthesis of toxins imposes a substantial cost. Typically, such costs have been quantified by measuring the elevation in metabolic rate induced by toxin depletion (i.e. during replenishment of toxin stores). More generally, we might expect that toxin depletion will induce shifts in a broad suite of fitness-relevant traits. In cane toads ( Rhinella marina ), toxic compounds that protect against predators and pathogens are stored in large parotoid (shoulder) glands. We used correlational and experimental approaches in field and laboratory settings to investigate impacts of toxin depletion on growth rate and behaviour in cane toads. In free-ranging toads, larger toxin stores were associated with smaller gonads and livers, suggesting energetic trade-offs between toxin production and both reproduction and energy metabolism. Experimental removal of toxin (by manually squeezing parotoid glands) reduced rates of growth in body mass in both captive and free-ranging toads. Radio tracking demonstrated that de-toxined toads dispersed more slowly than did control toads. Given that toxin stores in cane toads take several months to fully replenish, deploying toxin to repel a predator may impose a substantial cost, explaining why toads use toxin only as a final line of defence.
Pathology Associated With an Outbreak of Entamoebiasis in Wild Cane Toads (Rhinella marina) in Tropical Australia
Publisher: SAGE Publications
Date: 16-09-2019
Abstract: Infection due to Entamoeba spp. is known to cause serious disease in primates ( Entamoeba histolytica) and snakes ( Entamoeba invadens), but there are no detailed descriptions of the pathology associated with Entamoeba spp. infection in hibians. In 2014, an outbreak of entamoebiasis associated with a novel species of Entamoeba induced clinical illness and poor body condition in free-ranging cane toads in Australia’s Northern Territory. Here, we describe the gross pathology, histology, and clinical pathology linked to the outbreak. The study compared 25 toads with invasive entamoebiasis, defined as histologically visible amoebas within tissue, and 12 toads without invasive entamoebiasis. Grossly, affected toads had mild to marked congestion of colonic serosal vasculature, with variable thickening of the intestinal wall and serosanguineous to hemorrhagic colonic content. Histologically, invasive entamoebiasis manifested primarily as moderate to severe, variably hyperplastic to ulcerative colitis. The small intestine was affected in 10 of 25 toads, and 5 of 25 toads also had gastric lesions. Amoebas consistent in morphology with Entamoeba sp. were commonly intermingled with mucosal epithelium, frequently along the basement membrane, with deeper invasion into the superficial lamina propria in only 5 toads. Toads with invasive entamoebiasis had neutrophilia, monocytosis, and lymphopenia, and thus elevated neutrophil to lymphocyte ratios, suggestive of an inflammatory and/or stress leukogram.
Symptoms and treatment of mental illness among prisoners: A study of Michigan state prisons
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.IJLP.2013.04.008
Abstract: This study reports on a representative s le of prisoners in Michigan correctional facilities to determine the prevalence of psychiatric illness and the delivery of mental health (MH) services. Mental health assessments were conducted with 618 incarcerated subjects using the interRAI Correctional Facilities (interRAI CF). Subjects were randomly s led based on four strata: males in the general population, males in administrative segregation, males in special units, and females. The interRAI CF assessments were merged with secondary data provided by the Michigan Department of Corrections (MDOC) containing information on MH diagnoses or services that the subjects were receiving within the facilities, demographics, and sentencing. Study results show that 20.1% of men and 24.8% of women in Michigan prisons have a substantial level of MH symptoms and that 16.5% and 28.9%, respectively, are receiving MH services. However, when compared with Michigan Department of Corrections MH care records, 65.0% of prisoners who are experiencing symptoms of mental illness are not currently receiving any psychiatric services. The mis-match between symptoms and service delivery suggests the need for improved procedures for identifying and measuring psychiatric symptoms within Michigan correctional facilities to ensure that appropriate in iduals receive needed care. It is recommended that a standardized assessment process be implemented and conducted at regular intervals for targeting and improving psychiatric care in the prison system.
Habitat selection by bluetongue lizards (Tiliqua, Scincidae) in tropical Australia: A study using GPS telemetry
Publisher: Springer Science and Business Media LLC
Date: 07-06-2013
Abstract: Emerging global positioning system (GPS) technologies can clarify movement patterns of free-ranging animals in far more detail than has been possible with previous methods. We conducted long-term (mean, 65 days maximum, 221 days) GPS radio-tracking of 41 northern bluetongue lizards ( Tiliqua scincoides intermedia ) and 8 centralian bluetongue lizards ( T. multifasciata ) at two study sites in northwestern Australia, close to the border between Western Australia and the Northern Territory. In iduals of both species spent long periods within small and distinctive habitat patches, interspersed with longer directional relocations from one patch to the next. Our s ling showed that these patches of core activity differed significantly from the surrounding landscape in several respects. The patches provided relatively shaded, cool, and d conditions, with higher grass and more leaf-litter cover. The location of these patches in the landscape is probably determined by drainage patterns, soil moisture-holding ability, and stochastic recruitment of shade trees. These scattered patches provide a critically important habitat for lizards (and probably, other taxa) within this hot dry landscape. Future conservation and management strategies need to prioritize the retention of such sites, at a spatial scale that allows animals to move between them.
Responses of three sympatric snake species to tropical seasonality in northern Australia
Publisher: Cambridge University Press (CUP)
Date: 07-2002
DOI: 10.1017/S0266467402002365
Abstract: In the Australian wet–dry tropics, temperatures are high year-round but rainfall is concentrated in a 4-mo wet season. Regular nightly surveys in the Fogg Dam Nature Reserve provided data on temporal (monthly, seasonal) variation in biological attributes of three snake species: water pythons ( Liasis fuscus , Pythonidae), keelbacks ( Tropidonophis mairii , Colubridae) and slatey-grey snakes ( Stegonotus cucullatus , Colubridae). Adults of all three taxa were encountered more frequently during the dry season than the wet season, whereas juveniles were more commonly encountered in the wet season. The sex ratio among adult snakes also shifted seasonally, but in different ways in different species. These sex-ratio shifts probably reflect reproductive activity (mate-searching by males, oviposition migrations by females) and were accompanied by increased encounter rates. Feeding rates and body condition of keelbacks (a frog specialist) were highest during the wet season when frogs were most abundant. Rats migrated away from Fogg Dam during the wet season, and most pythons (rat specialists) left this area to follow their prey. The pythons that remained at Fogg Dam exhibited low feeding rates and poor body condition. Slatey-grey snakes (a generalist predator) showed less seasonal variation in feeding rates or body condition. Our data show that tropical seasonality induces strong fluctuations in many attributes of snake populations, and that patterns of response differ both among and within species.
Nesting snakes (Tropidonophis mairii, Colubridae) selectively oviposit in sites that provide evidence of previous successful hatching
Publisher: Canadian Science Publishing
Date: 08-2005
DOI: 10.1139/Z05-115
Abstract: In oviparous species without parental care, nesting females must select an oviposition site that provides incubation conditions favourable to the developing eggs. Abiotic cues (e.g., temperature, moisture) are well known to influence oviposition-site selection, but the potential role of biotic cues (e.g., the presence of eggshells from previous successfully hatched clutches or the scent of egg predators) has rarely been examined in this respect. To test whether nesting females use such cues, we collected gravid keelback snakes (Tropidonophis mairii (Gray, 1841), Colubridae) in tropical Australia and gave them a choice of potential nesting sites in captivity. Females selectively oviposited in sites containing empty eggshells rather than in control sites but did not avoid the scent of a sympatric egg predator (the slatey-grey snake, Stegonotus cucullatus (Duméril, Bibron and Duméril, 1854)) indeed, eggshells of this taxon were as effective as keelback eggs in attracting oviposition. Our study adds to growing evidence that nesting females assess and respond to a erse array of biotic as well as abiotic cues that predict the probability of successful incubation for their eggs.
PERMANENT GENETIC RESOURCES: Characterization of tri‐ and tetranucleotide microsatellite loci for the slatey‐grey snake (Stegonotus cucullatus, Colubridae)
Publisher: Wiley
Date: 03-2008
DOI: 10.1111/J.1471-8286.2007.01982.X
Abstract: We characterized nine polymorphic microsatellite (six trinucleotides and three tetranucleotides) loci for the slatey-grey snake (Stegonotus cucullatus) from Australia, in order to study the mating system of this species. Based on a total of 100 s les, the number of alleles per locus ranged from three to 10, and the observed and expected heterozygosities ranged from 0.62 to 0.86 and from 0.53 to 0.83, respectively.
The use of a brief mental health screener to enhance the ability of police officers to identify persons with serious mental disorders
Publisher: Elsevier BV
Date: 07-2016
DOI: 10.1016/J.IJLP.2016.02.031
Abstract: Police agencies in Canada and elsewhere have received much criticism over how they respond to persons with serious mental disorders. The adequacy of training provided to police officers on mental health issues and in particular on recognizing indicators of serious mental disorders has been a major concern. This paper describes the process that led to the development of a new brief mental health screener (interRAI Brief Mental Health Screener, BMHS) designed to assist police officers to better identify persons with serious mental disorders. The interRAI BMHS was developed in collaboration with interRAI, an international, not-for-profit consortium of researchers. The government of Ontario had previously partnered with interRAI to develop and implement the Resident Assessment Instrument for Mental Health (RAI-MH), the assessment system mandated for use on all persons admitted into inpatient psychiatric care in the province. Core items on the interRAI BMHS were obtained through analysis (N=41,019) of RAI-MH data together with input from representatives from health care, police services, and patient groups. Two police services in southwestern Ontario completed forms (N=235) on persons thought to have a mental disorder. Patient records were later accessed to determine patient disposition. The use of summary and inferential statistics revealed that the variables significantly associated with being taken to hospital by police included performing a self-injurious act in the past 30days, and others being concerned over the person's risk for self-injury. Variables significantly associated with being admitted included abnormal thought process, delusions, and hallucinations. The results of the study indicate that the 14-variable algorithm used to construct the interRAI BMHS is a good predictor of who was most likely to be taken to hospital by police officers and who was most likely to be admitted. The instrument is an effective means of capturing and standardizing police officer observations enabling them to provide more and better quality information to emergency department (ED) staff. Teaching police officers to use the form constitutes enhanced training on major indicators of serious mental disorders. Further, given that items on the interRAI BMHS are written in the language of the health system, language acts as common currency between police officers and ED staff laying the foundation for a more collaborative approach between the systems.
Radiation dose and image quality in adult computed tomography scans
Publisher: American Scientific Publishers
Date: 02-2018
Department of Error
Publisher: Elsevier BV
Date: 09-2017
The impact of lungworm parasites on rates of dispersal of their anuran host, the invasive cane toad
Publisher: Springer Science and Business Media LLC
Date: 28-09-2016
MHC diversity and female age underpin reproductive success in an Australian icon; the Tasmanian Devil
Publisher: Springer Science and Business Media LLC
Date: 08-03-2018
DOI: 10.1038/S41598-018-20934-9
Abstract: Devil Facial Tumour Disease (DFTD), a highly contagious cancer, has decimated Tasmanian devil ( Sarcophilus harrisii ) numbers in the wild. To ensure its long-term survival, a captive breeding program was implemented but has not been as successful as envisaged at its launch in 2005. We therefore investigated the reproductive success of 65 captive devil pair combinations, of which 35 produced offspring (successful pairs) whereas the remaining 30 pairs, despite being observed mating, produced no offspring (unsuccessful pairs). The devils were screened at six MHC Class I-linked microsatellite loci. Our analyses revealed that younger females had a higher probability of being successful than older females. In the successful pairs we also observed a higher difference in total number of heterozygous loci, i.e. when one devil had a high total number of heterozygous loci, its partner had low numbers. Our results therefore suggest that devil reproductive success is subject to disruptive MHC selection, which to our knowledge has never been recorded in any vertebrate. In order to enhance the success of the captive breeding program the results from the present study show the importance of using young (2-year old) females as well as subjecting the devils to MHC genotyping.
The things they carried: The pathogenic effects of old and new parasites following the intercontinental invasion of the Australian cane toad (Rhinella marina)
Publisher: Elsevier BV
Date: 12-2017
Is the behavioural divergence between range-core and range-edge populations of cane toads (Rhinella marina) due to evolutionary change or developmental plasticity?
Publisher: The Royal Society
Date: 10-2017
DOI: 10.1098/RSOS.170789
Abstract: In iduals at the leading edge of expanding biological invasions often show distinctive phenotypic traits, in ways that enhance their ability to disperse rapidly and to function effectively in novel environments. Cane toads ( Rhinella marina ) at the invasion front in Australia exhibit shifts in morphology, physiology and behaviour (directionality of dispersal, boldness, risk-taking). We took a common-garden approach, raising toads from range-core and range-edge populations in captivity, to see if the behavioural ergences observed in wild-caught toads are also evident in common-garden offspring. Captive-raised toads from the invasion vanguard population were more exploratory and bolder (more prone to ‘risky’ behaviours) than toads from the range core, which suggests that these are evolved, genetic traits. Our study highlights the importance of behaviour as being potentially adaptive in invasive populations and adds these behavioural traits to the increasing list of phenotypic traits that have evolved rapidly during the toads' 80-year spread through tropical Australia.
Supplementary material from Intergenerational effects of manipulating DNA methylation in the early life of an iconic invader
Publisher: The Royal Society
Date: 2021
Within‐population variation in dietary traits: implications for vulnerability and impact of imperiled keystone predators
Publisher: Wiley
Date: 10-2020
DOI: 10.1002/ECS2.3136
Effects of invasion history on physiological responses to immune system activation in invasive Australian cane toads
Publisher: PeerJ
Date: 06-10-2017
DOI: 10.7717/PEERJ.3856
Abstract: The cane toad ( Rhinella marina ) has undergone rapid evolution during its invasion of tropical Australia. Toads from invasion front populations (in Western Australia) have been reported to exhibit a stronger baseline phagocytic immune response than do conspecifics from range core populations (in Queensland). To explore this difference, we injected wild-caught toads from both areas with the experimental antigen lipopolysaccharide (LPS, to mimic bacterial infection) and measured whole-blood phagocytosis. Because the hypothalamic-pituitary-adrenal axis is stimulated by infection (and may influence immune responses), we measured glucocorticoid response through urinary corticosterone levels. Relative to injection of a control (phosphate-buffered saline), LPS injection increased both phagocytosis and the proportion of neutrophils in the blood. However, responses were similar in toads from both populations. This null result may reflect the ubiquity of bacterial risks across the toad’s invaded range utilization of this immune pathway may not have altered during the process of invasion. LPS injection also induced a reduction in urinary corticosterone levels, perhaps as a result of chronic stress.
Female distribution affects mate searching and sexual selection in male northern water snakes (Nerodia sipedon)
Publisher: Springer Science and Business Media LLC
Date: 03-12-1999
The global burden of tuberculosis: results from the Global Burden of Disease Study 2015
Publisher: Elsevier BV
Date: 03-2018
Habitat use of the introduced cane toad (Rhinella marina) and native frog species in tropical Australia
Publisher: Cambridge University Press (CUP)
Date: 17-09-2015
DOI: 10.1017/S0266467415000474
Abstract: The ecological impacts of introduced species can reveal mechanisms underlying habitat selection and behaviour. We investigated the habitat use of native frog species and the invasive cane toads ( Rhinella marina ) in tropical northern Australia to measure overlap in habitat use, and to test if the presence of the cane toad influences frog behaviour. Native frog species and the cane toad both preferred habitats close to water and unvegetated holes. However, native frogs were found further from water (on average 19.4 m) than were toads (on average 12.6 m), and preferred areas with higher vegetation (8–50 cm) than did toads, which were more abundant in vegetation lower than 8 cm. For both types of anuran, the next neighbour was more often of the same type (89% in frogs, 52% in toads) than expected by chance (observed ratio: 75% frogs vs 25% toads), reflecting these differences in habitat use. Our counts of frog abundance increased on average 14.5% in areas from which we removed cane toads temporarily. This result suggests that cane toads inhibit the activity of native anurans either by inducing avoidance, or by reducing activity. By modifying the behaviour and spatial distribution of native taxa, invasive cane toads may curtail activities such as feeding and breeding.
Do parasites matter? Assessing the fitness consequences of haemogregarine infection in snakes
Publisher: Canadian Science Publishing
Date: 05-2006
DOI: 10.1139/Z06-044
Abstract: Although much research in evolutionary ecology is based upon the premise that high levels of parasitism impair the host's functioning, the assumed link between parasitism and fitness has been assessed for relatively few kinds of animals. At our study site in tropical Australia, keelback snakes ( Tropidonophis mairii (Gray, 1841), Colubridae) are heavily infected with haemogregarine blood parasites: 90% of snakes that we tested carried the parasite, with the proportion of erythrocytes containing haemogregarines averaging 15% and ranging up to a remarkable 64%. Prevalence increased with snake body size, but intensity decreased with age. Unlike lizards studied previously, the snakes did not respond to haemogregarine infection by releasing immature erythrocytes into the circulation. In striking contrast to results from a recent study on a sympatric snake species, we did not find any empirical links between parasite numbers and several measures of host fitness (body condition, growth rate, feeding rate, antipredator behaviour, locomotor performance, reproductive status, reproductive output, and recapture rate). The association between this parasite and its host thus appears to be surprisingly benign, suggesting that host–parasite interactions sometimes may have only trivial consequences for host fitness in natural populations. Plausibly, host–parasite coevolution weakens or eliminates fitness costs of parasitism.
The loneliness of the long-distance toad: invasion history and social attraction in cane toads ( Rhinella marina )
Publisher: The Royal Society
Date: 11-2017
Abstract: In iduals at the leading edge of a biological invasion constantly encounter novel environments. These pioneers may benefit from increased social attraction, because low population densities reduce competition and risks of pathogen transfer, and increase benefits of information transfer. In standardized trials, cane toads ( Rhinella marina ) from invasion-front populations approached conspecifics more often, and spent more time close to them, than did conspecifics from high-density, long-colonized populations.
Invasive parasites in multiple invasive hosts: the arrival of a new host revives a stalled prior parasite invasion
Publisher: Wiley
Date: 26-02-2013
Effects of an invasive species on refuge-site selection by native fauna: The impact of cane toads on native frogs in the Australian tropics
Publisher: Wiley
Date: 08-04-2014
DOI: 10.1111/AEC.12044
Effects of reproduction on the antipredator tactics of snakes (Tropidonophis mairii, Colubridae)
Publisher: Springer Science and Business Media LLC
Date: 31-03-2004
Factors affecting the vulnerability of cane toads (Bufo marinus) to predation by ants
Publisher: Oxford University Press (OUP)
Date: 30-03-2010
Spatial ecology of bluetongue lizards (Tiliqua spp.) in the Australian wet-dry tropics
Publisher: Wiley
Date: 20-08-2013
Effects of reproduction on survival and growth of female northern water snakes, Nerodia sipedon
Publisher: Canadian Science Publishing
Date: 03-1997
DOI: 10.1139/Z97-052
Abstract: The cornerstone of life-history theory is the expectation that current reproduction will have a detrimental effect on survival and (or) future reproduction. When fecundity increases with body size, the cost to future reproduction arises through decreased growth of reproductive in iduals. We investigated the effects of reproduction on aspects of survival and growth in female northern water snakes (Nerodia sipedon). We did not find a decrease in survival associated with mating despite the conspicuousness of mating aggregations, and pregnancy did not impair locomotor ability. We found evidence of a decrease in over-winter survival of reproductive females related to their emaciated state following parturition. Reproductive females grew less in length than nonreproductive females, but increased similarly in mass. Following parturition, reproductive females weighed less than in the spring, indicating that mass gain prior to parturition was invested in the litter and that most foraging occurred prior to ovulation. Captive reproductive females given food ad libitum grew in length at a rate similar to free-living reproductive females, but increased more in mass. Captive females weighed more after giving birth than in the spring, indicating that unlike that of females in the wild, some of their mass increase was due to energy storage, and also that they continued to feed after ovulation. Consistent with the prediction that smaller females would benefit more than larger females from reproducing less and growing more to increase future fecundity, we found that smaller females participated less in mating aggregations and reproduced less often.
Cycle of coercion: Experiences of maltreatment and disciplinary measures in Canadian inmates
Publisher: Emerald
Date: 10-06-2014
DOI: 10.1108/IJPH-09-2013-0043
Abstract: – In spite of past and current efforts at implementing effective rehabilitative interventions in carceral settings, institutions of confinement are primarily concerned with the maintenance of order within their walls. The purpose of this paper is to better understand associations between inmates’ developmental background and the experience of institutional discipline, to collect information on childhood maltreatment and disciplinary measures for a s le of Canadian prisoners. – Information relative to socio-economic background, childhood maltreatment and experience of discipline while in custody was obtained using face-to-face interviews and institutional file review for a s le of 416 male and 106 female offenders in Canadian provincial institutions. – Results from logistic regression analyses provided support for the association between childhood maltreatment and the experience of discipline, specifically in the form of increased monitoring from correctional staff. Furthermore, this association was found to be more pronounced for female offenders. – The findings highlight the need to incorporate a developmental perspective to current understanding of the use of disciplinary interventions in a prison environment. Such an approach may allow for preventing the enactment of a cycle of coercion, with negative consequences for the inmates. – This study is original in its use of latent variable analytic methods to uncover the structure underlying the construct of childhood maltreatment in adult offenders. In addition, it provides valuable data of interest to researchers, corrections personnel and policy makers on the possible links between earlier developmental experiences and adjustment to the prison environment.
The behaviour of sea snakes (Emydocephalus annulatus) shifts with the tides
Publisher: Springer Science and Business Media LLC
Date: 09-07-2020
DOI: 10.1038/S41598-020-68342-2
Abstract: Tidal cycles are known to affect the ecology of many marine animals, but logistical obstacles have discouraged behavioural studies on sea snakes in the wild. Here, we analyse a large dataset (1,445 observations of 126 in iduals) to explore tidally-driven shifts in the behaviour of free-ranging turtle-headed sea snakes ( Emydocephalus annulatus , Hydrophiinae) in the Baie des Citrons, New Caledonia. Snakes tended to move into newly-inundated areas with the rising tide, and became more active (e.g. switched from inactivity to mate-searching and courting) as water levels rose. However, the relative use of alternative habitat types was largely unaffected by tidal phase.
Intergenerational effects of manipulating DNA methylation in the early life of an iconic invader
Publisher: The Royal Society
Date: 19-04-2021
Abstract: In response to novel environments, invasive populations often evolve rapidly. Standing genetic variation is an important predictor of evolutionary response but epigenetic variation may also play a role. Here, we use an iconic invader, the cane toad ( Rhinella marina ), to investigate how manipulating epigenetic status affects phenotypic traits. We collected wild toads from across Australia, bred them, and experimentally manipulated DNA methylation of the subsequent two generations (G1, G2) through exposure to the DNA methylation inhibitor zebularine and/or conspecific tadpole alarm cues. Direct exposure to alarm cues (an indicator of predation risk) increased the potency of G2 tadpole chemical cues, but this was accompanied by reductions in survival. Exposure to alarm cues during G1 also increased the potency of G2 tadpole cues, indicating intergenerational plasticity in this inducible defence. In addition, the negative effects of alarm cues on tadpole viability (i.e. the costs of producing the inducible defence) were minimized in the second generation. Exposure to zebularine during G1 induced similar intergenerational effects, suggesting a role for alteration in DNA methylation. Accordingly, we identified intergenerational shifts in DNA methylation at some loci in response to alarm cue exposure. Substantial demethylation occurred within the sodium channel epithelial 1 subunit gamma gene ( SCNN1G ) in alarm cue exposed in iduals and their offspring. This gene is a key to the regulation of sodium in epithelial cells and may help to maintain the protective epidermal barrier. These data suggest that early life experiences of tadpoles induce intergenerational effects through epigenetic mechanisms, which enhance larval fitness. This article is part of the theme issue ‘How does epigenetics influence the course of evolution?’
Increased rates of dispersal of free-ranging cane toads (Rhinella marina) during their global invasion
Publisher: Springer Science and Business Media LLC
Date: 07-12-2021
DOI: 10.1038/S41598-021-02828-5
Abstract: Invasions often accelerate through time, as dispersal-enhancing traits accumulate at the expanding range edge. How does the dispersal behaviour of in idual organisms shift to increase rates of population spread? We collate data from 44 radio-tracking studies (in total, of 650 animals) of cane toads ( Rhinella marina ) to quantify distances moved per day, and the frequency of displacement in their native range (French Guiana) and two invaded areas (Hawai’i and Australia). We show that toads in their native-range, Hawai’i and eastern Australia are relatively sedentary, while toads dispersing across tropical Australia increased their daily distances travelled from 20 to 200 m per day. That increase reflects an increasing propensity to change diurnal retreat sites every day, as well as to move further during each nocturnal displacement. Daily changes in retreat site evolved earlier than did changes in distances moved per night, indicating a breakdown in philopatry before other movement behaviours were optimised to maximise dispersal.
Skin resistance to water gain and loss has changed in cane toads (Rhinella marina) during their Australian invasion
Publisher: Wiley
Date: 11-10-2020
DOI: 10.1002/ECE3.6895
In an arms race between host and parasite, a lungworm’s ability to infect a toad is determined by host susceptibility, not parasite preference
Publisher: Cold Spring Harbor Laboratory
Date: 19-10-2021
DOI: 10.1101/2021.10.19.464902
Abstract: Evolutionary arms races can alter both parasite infectivity and host resistance, and it is difficult to separate the effects of these twin determinants of infection outcomes. Using a co-introduced, invasive host-parasite system (the lungworm Rhabdias pseudosphaerocephala and the cane toad Rhinella marina), we quantified behavioural responses of parasite larvae to skin-chemical cues of toads from different invasive populations, and rates at which hosts became infected following standardised exposure to lungworms. Chemical cues from toad skin altered host-seeking behaviour by parasites, similarly among populations. The number of infection attempts (parasite larvae entering the host’s body) also did not differ between populations, but rates of successful infection (establishment of adult worm in host lungs) was higher for range-edge toads than for range-core conspecifics. Thus, lower resistance to parasite infection in range-edge toads appears to be due to less effective immune defences of the host rather than differential behavioural responses of the parasite. In this ongoing host-parasite arms-race, changing outcomes appear to be driven by shifts in host immunocompetence.
Measuring amphibian immunocompetence: validation of the phytohemagglutinin skin-swelling assay in the cane toad, Rhinella marina
Publisher: Wiley
Date: 02-02-2011
Using experimental de-worming to measure the immunological and pathological impacts of lungworm infection in cane toads
Publisher: Elsevier BV
Date: 12-2017
Divergence in host–parasite interactions during the cane toad's invasion of Australia
Publisher: Wiley
Date: 08-2022
DOI: 10.1002/ECE3.9220
Abstract: Coevolutionary host–parasite “arms races” can be disrupted by new evolutionary forces imposed by biological invasions, affecting both host and parasite densities, as well as their traits. The spread of cane toads ( Rhinella marina ) and their parasitic lungworm ( Rhabdias pseudosphaerocephala ) across tropical Australia provides an ideal opportunity to study a perturbed host–parasite system. We conducted a cross‐infection experiment using common‐garden‐reared toads and lungworms from three regions (comprising long‐established, intermediate, and recently invaded sites across tropical Australia) to quantify traits of the parasite (infectivity and virulence) and the host (resistance and tolerance). Specifically, we assessed whether patterns of host–parasite co‐adaptation were better explained by spatial distances versus time since the separation of host and parasite populations. Infection success was highest when toads from long‐established populations were exposed to lungworms from close to the invasion front and lowest when frontal toads were exposed to parasites from older populations. This suggests that both parasite infectivity and host resistance have increased over the course of invasion. In contrast, most virulence/tolerance traits have not consistently increased or decreased during invasion. Higher parasite burdens were associated with increased feeding performance in toads and faster growth in lungworms, counter‐intuitive results that suggest host manipulation by the parasite.
Burden of diarrhea in the Eastern Mediterranean Region, 1990–2015: Findings from the Global Burden of Disease 2015 study
Publisher: Springer Science and Business Media LLC
Date: 03-08-2017
Invader immunology: Invasion history alters immune system function in cane toads (Rhinella marina) in tropical Australia
Publisher: Wiley
Date: 14-11-2015
DOI: 10.1111/ELE.12390
Abstract: Because an in idual's investment into the immune system may modify its dispersal rate, immune function may evolve rapidly in an invader. We collected cane toads (Rhinella marina) from sites spanning their 75-year invasion history in Australia, bred them, and raised their progeny in standard conditions. Evolved shifts in immune function should manifest as differences in immune responses among the progeny of parents collected in different locations. Parental location did not affect the offspring's cell-mediated immune response or stress response, but blood from the offspring of invasion-front toads had more neutrophils, and was more effective at phagocytosis and killing bacteria. These latter measures of immune function are negatively correlated with rate of dispersal in free-ranging toads. Our results suggest that the invasion of tropical Australia by cane toads has resulted in rapid genetically based compensatory shifts in the aspects of immune responses that are most compromised by the rigours of long-distance dispersal.
Evolutionary shifts in anti-predator responses of invasive cane toads (Rhinella marina)
Publisher: Springer Science and Business Media LLC
Date: 16-08-2017
Noisy neighbours at the frog pond: effects of invasive cane toads on the calling behaviour of native Australian frogs
Publisher: Springer Science and Business Media LLC
Date: 25-02-2015
Geographic variation in bacterial assemblages on cane toad skin is influenced more by local environments than by evolved changes in host traits
Publisher: The Company of Biologists
Date: 06-02-2023
DOI: 10.1242/BIO.059641
Abstract: Bacterial assemblages on hibian skin may play an important role in protecting hosts against infection. In hosts that occur over a range of environments, geographic variation in composition of bacterial assemblages might be due to direct effects of local factors and/or to evolved characteristics of the host. Invasive cane toads (Rhinella marina) are an ideal candidate to evaluate environmental and genetic mechanisms, because toads have evolved major shifts in physiology, morphology, and behavior during their brief history in Australia. We used s les from free-ranging toads to quantify site-level differences in bacterial assemblages and a common-garden experiment to see if those differences disappeared when toads were raised under standardised conditions at one site. The large differences in bacterial communities on toads from different regions were not seen in offspring raised in a common environment. Relaxing bacterial clustering to operational taxonomic units in place of licon sequence variants likewise revealed high similarity among bacterial assemblages on toads in the common-garden study, and with free-ranging toads captured nearby. Thus, the marked geographic ergence in bacterial assemblages on wild-caught cane toads across their Australian invasion appears to result primarily from local environmental effects rather than evolved shifts in the host.
Female phenotype, life history, and reproductive success in free-ranging snakes (Tropidonophis mairii)
Publisher: Wiley
Date: 10-2005
DOI: 10.1890/04-1805
Bigger babies are bolder: effects of body size on personality of hatchling snakes
Publisher: Brill
Date: 2016
DOI: 10.1163/1568539X-00003343
Abstract: An animal’s susceptibility to risk may be partly dependent on its body size. But are larger in iduals bolder? We assessed this question by measuring time to emerge from a shelter in repeated trials on hatchling keelback snakes ( Tropidonophis mairii ). Estimates of repeatability of emergence times suggested they measure some underlying personality dimension related to boldness. Larger hatchlings emerged from shelter sooner than small ones. Hatchling mass of keelbacks is substantially influenced both by maternal phenotype and by incubation conditions. Given the environmental basis of much of the variation in offspring size, the size-boldness association may reflect a facultative ability to adjust behavioural tactics to body size, as well as innate differences in personality traits between large versus small hatchlings. The link between size and boldness suggests that the survival advantage of larger offspring size in this population may be driven by snake behaviour as well as morphology.
Maternal body size influences offspring immune configuration in an oviparous snake
Publisher: The Royal Society
Date: 03-2016
DOI: 10.1098/RSOS.160041
Abstract: Like most ectothermic vertebrates, keelback snakes ( Tropidonophis mairii ) do not exhibit parental care. Thus, offspring must possess an immune system capable of dealing with challenges such as pathogens, without assistance from an attendant parent. We know very little about immune system characteristics of neonatal reptiles, including the magnitude of heritability and other maternal influences. To identify sources of variation in circulating white blood cell (WBC) concentrations and differentials, we examined blood smears from 246 hatchling snakes and their field-caught mothers. WBC concentrations were lower in hatchlings than in adults, and hatchlings had more basophils and fewer azurophils than adults. A hatchling keelback's WBC differential was also influenced by its sex and body size. Although hatchling WBC measures exhibited negligible heritability, they were strongly influenced by maternal body size and parasite infection (but not by maternal body condition, relative clutch mass or time in captivity). Larger mothers produced offspring with more azurophils and fewer lymphocytes. The mechanisms and consequences of WBC variation are currently unknown, but if these maternal effects enhance offspring fitness, the impact of maternal body size on reproductive success may be greater than expected simply from allometric increases in the numbers and sizes of progeny.
Do changes in body mass alter white blood cell profiles and immune function in Australian cane toads ( Rhinella marina )?
Publisher: The Royal Society
Date: 12-06-2023
Abstract: Variation in food resources can result in dramatic fluctuations in the body condition of animals dependent on those resources. Decreases in body mass can disrupt patterns of energy allocation and impose stress, thereby altering immune function. In this study, we investigated links between changes in body mass of captive cane toads ( Rhinella marina ), their circulating white blood cell populations, and their performance in immune assays. Captive toads that lost weight over a three-month period had increased levels of monocytes and heterophils and reduced levels of eosinophils. Basophil and lymphocyte levels were unrelated to changes in mass. Because in iduals that lost mass had higher heterophil levels but stable lymphocyte levels, the ratio of these cell types was also higher, partially consistent with a stress response. Phagocytic ability of whole blood was higher in toads that lost mass, owing to increased circulating levels of phagocytic cells. Other measures of immune performance were unrelated to mass change. These results highlight the challenges faced by invasive species as they expand their range into novel environments which may impose substantial seasonal changes in food availability that were not present in the native range. In iduals facing energy restrictions may shift their immune function towards more economical and general avenues of combating pathogens. This article is part of the theme issue ‘Amphibian immunity: stress, disease and ecoimmunology’.
Life history traits of the sea snake Emydocephalus annulatus, based on a 17-yr study
Publisher: Springer Science and Business Media LLC
Date: 08-07-2020
Sex ratios, mating behavior and sexual size dimorphism of the northern water snake, Nerodia sipedon
Publisher: Springer Science and Business Media LLC
Date: 05-1995
DOI: 10.1007/BF00167791
Do changing moisture levels during incubation influence phenotypic traits of hatchling snakes (Tropidonophis mairii, Colubridae)?
Publisher: University of Chicago Press
Date: 07-2005
DOI: 10.1086/430231
Abstract: Phenotypic traits (e.g., size, strength, speed) of hatchlings in many reptile species are influenced by hydric conditions in the nest. Previous experiments have focused on comparisons between eggs maintained under constant (but different) conditions, but eggs in natural nests frequently experience strong temporal shifts in soil water content during incubation. Keelback snakes (Tropidonophis mairii) in the Australian wet-dry tropics nest over most of the year, so early nests experience decreasing water availability during development, late nests experience increases, and others (midyear) remain stable in this respect. We mimicked these three conditions and incubated 54 eggs (nine from each of six clutches) in a split-clutch design to maintain the same average water content but with differing trajectories through incubation. The experimental treatments significantly affected the total amount of water taken up by the eggs (and thus final egg mass), but incubation periods were unaffected. Hatchling size but not strength showed minor but statistically significant effects of incubation regimes. The ability of keelback eggs to take up excess water whenever it becomes available (either early or late in development) and to retain it even when conditions change buffers embryogenesis effectively (but not completely) against fluctuations in soil water conditions.
Apparent lack of spill-over of parasites from an invasive anuran: PCR detects Entamoeba in cane toads (Rhinella marina) but not in sympatric Australian native frogs
Publisher: Elsevier BV
Date: 08-2020
Rapid evolution of parasite life history traits on an expanding range-edge
Publisher: Wiley
Date: 08-02-2012
DOI: 10.1111/J.1461-0248.2012.01742.X
Abstract: Parasites of invading species undergoing range advance may be exposed to powerful new selective forces. Low host density in range-edge populations h ers parasite transmission, requiring the parasite to survive longer periods in the external environment before encountering a potential host. These conditions should favour evolutionary shifts in offspring size to maximise parasite transmission. We conducted a common-garden experiment to compare life history traits among seven populations of the nematode lungworm (Rhabdias pseudosphaerocephala) spanning from the parasite population core to the expanding range-edge in invasive cane toads (Rhinella marina) in tropical Australia. Compared to conspecifics from the population core, nematodes from the range-edge exhibited larger eggs, larger free-living adults and larger infective larvae, and reduced age at maturity in parasitic adults. These results support a priori predictions regarding adaptive changes in offspring size as a function of invasion history, and suggest that parasite life history traits can evolve rapidly in response to the selective forces exerted by a biological invasion.
Locomotor performance of cane toads differs between native-range and invasive populations
Publisher: The Royal Society
Date: 07-2017
DOI: 10.1098/RSOS.170517
Abstract: Invasive species provide a robust opportunity to evaluate how animals deal with novel environmental challenges. Shifts in locomotor performance—and thus the ability to disperse—(and especially, the degree to which it is constrained by thermal and hydric extremes) are of special importance, because they might affect the rate that an invader can spread. We studied cane toads ( Rhinella marina ) across a broad geographical range: two populations within the species' native range in Brazil, two invasive populations on the island of Hawai'i and eight invasive populations encompassing the eastern, western and southern limits of the toad invasion in Australia. A toad's locomotor performance on a circular raceway was strongly affected by both its temperature and its hydration state, but the nature and magnitude of those constraints differed across populations. In their native range, cane toads exhibited relatively low performance (even under optimal test conditions) and a rapid decrease in performance at lower temperatures and hydration levels. At the other extreme, performance was high in toads from southern Australia, and virtually unaffected by desiccation. Hawai'ian toads broadly resembled their Brazilian conspecifics, plausibly reflecting similar climatic conditions. The invasion of Australia has been accompanied by a dramatic enhancement in the toads' locomotor abilities, and (in some populations) by an ability to maintain locomotor performance even when the animal is cold and/or dehydrated. The geographical ergences in performance among cane toad populations graphically attest to the adaptability of invasive species in the face of novel abiotic challenges.
Health effects of dietary risks in 195 countries, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017
Publisher: Elsevier BV
Date: 05-2019
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.
Sexual selection favours large body size in males of a tropical snake (Stegonotus cucullatus, Colubridae)
Publisher: Elsevier BV
Date: 2009
Effects of an invasive anuran the cane toad (Bufo marinus) on the invertebrate fauna of a tropical Australian floodplain
Publisher: Wiley
Date: 18-07-2006
Toad on the road: Use of roads as dispersal corridors by cane toads (Bufo marinus) at an invasion front in tropical Australia
Publisher: Elsevier BV
Date: 11-2006
Beastly Bondage: The Costs of Amplexus in Cane Toads (Bufo marinus)
Publisher: American Society of Ichthyologists and Herpetologists (ASIH)
Date: 23-02-2009
DOI: 10.1643/CE-08-036
Untangling the influence of biotic and abiotic factors on habitat selection by a tropical rodent
Publisher: Springer Science and Business Media LLC
Date: 18-06-2021
DOI: 10.1038/S41598-021-91748-5
Abstract: Understanding how animal populations respond to environmental factors is critical because large-scale environmental processes (e.g., habitat fragmentation, climate change) are impacting ecosystems at unprecedented rates. On an overgrazed floodplain in north-western Australia, a native rodent (Pale Field Rat, Rattus tunneyi ) constructs its burrows primarily beneath an invasive tree (Chinee Apple, Ziziphus mauritiana ) rather than native trees. The dense thorny foliage of the Chinee Apple may allow high rat densities either because of abiotic effects (shade, in a very hot environment) or biotic processes (protection from tr ling and soil compaction by feral horses, and/or predation). To distinguish between these hypotheses, we manipulated Chinee Apple foliage to modify biotic factors (access to horses and predators) but not shade levels. We surveyed the rat population with Elliott traps under treatment and control trees and in the open woodland, in two seasons (the breeding season—January, and the nesting season—May). In the breeding season, we ran giving-up density experiments (GUD) with food trays, to assess the perceived risk of predation by rats across our three treatments. Selective trimming of foliage did not affect thermal regimes underneath the trees but did allow ingress of horses and we observed two collapsed burrows as a consequence (although long term impacts of horses were not measured). The perceived predation risk also increased (GUD values at food trays increased) and was highest in the open woodland. Our manipulation resulted in a shift in rat sex ratios (indicating female preference for breeding under control but not foliage-trimmed trees) and influenced rat behaviour (giving-up densities increased large dominant males inhabited the control but not treatment trees). Our data suggest that the primary benefit of the Chinee Apple tree to native rodents lies in physical protection from predators and (potentially) feral horses, rather than in providing cooler microhabitat.
First in family Rhabdiasidae: the reference-guided genome assembly of an invasive parasite, the cane toad lungworm (Rhabdias pseudosphaerocephala)
Publisher: Cold Spring Harbor Laboratory
Date: 28-02-2023
DOI: 10.1101/2023.02.28.530339
Abstract: Rhabdias pseudosphaerocephala is a well-studied invasive nematode parasite of hibians. However, there are several outstanding questions about R. pseudosphaerocephala that are best answered using genomic data. This species differs phenotypically across its invasive range. These differences are challenging to interpret because this species is part of a complex that is erse and cryptic in its home-range, and we do not know how many species from this complex originally colonised Australia. For this reason, it is unknown whether the phenotypic differences across the introduced range are due to intraspecific differentiation between populations or due to the presence of multiple species. In addition, there is little consensus in the placement of Rhabdiasidae family within the phylum Nematoda, making it difficult to perform comparative analyses with other nematodes. Within this paper, we assemble a reference genome for R. pseudosphaerocephala , the first assembly of any Rhabdiasidae species. We then use resequencing data to address outstanding questions about this species. Specifically, we combine population genetic and phylogenetic analyses to determine that there is likely only a single R. pseudosphaerocephala lineage within Australia, and identify that the invasive range population is closely related to home rage isolates that infect similar host species. We present compelling evidence for a genetic bottleneck following introduction to Australia and genetic differentiation occurring between invasive range populations. We then use genome-scale phylogenomic analysis to place the Rhabdiasidae family in the suborder Rhabditina. Ultimately, this paper brings the study of Rhabdiasidae into the genomic era, and sheds light on its ancient and modern evolutionary history.
Effects of seasonal aridity on the ecology and behaviour of invasive cane toads in the Australian wet-dry tropics
Publisher: Wiley
Date: 22-08-2011
An evolutionary process that assembles phenotypes through space rather than through time
Publisher: Proceedings of the National Academy of Sciences
Date: 21-03-2011
Abstract: In classical evolutionary theory, traits evolve because they facilitate organismal survival and/or reproduction. We discuss a different type of evolutionary mechanism that relies upon differential dispersal. Traits that enhance rates of dispersal inevitably accumulate at expanding range edges, and assortative mating between fast-dispersing in iduals at the invasion front results in an evolutionary increase in dispersal rates in successive generations. This cumulative process (which we dub “spatial sorting”) generates novel phenotypes that are adept at rapid dispersal, irrespective of how the underlying genes affect an organism's survival or its reproductive success. Although the concept is not original with us, its revolutionary implications for evolutionary theory have been overlooked. A range of biological phenomena (e.g., acceleration of invasion fronts, insular flightlessness, preadaptation) may have evolved via spatial sorting as well as (or rather than) by natural selection, and this evolutionary mechanism warrants further study.
Helpful invaders: Can cane toads reduce the parasite burdens of native frogs?
Publisher: Elsevier BV
Date: 12-2015
The ecological and life history correlates of boldness in free-ranging lizards
Publisher: Wiley
Date: 03-2018
DOI: 10.1002/ECS2.2125
Growth and sexual size dimorphism in northern water snakes (Nerodia sipedon)
Publisher: JSTOR
Date: 02-08-1999
DOI: 10.2307/1447605
A native dasyurid predator (common planigale, Planigale maculata) rapidly learns to avoid a toxic invader
Publisher: Wiley
Date: 08-10-2008
Spinal arthritis in invasive cane toads is linked to rate of dispersal as well as to latitude
Publisher: Springer Science and Business Media LLC
Date: 27-09-2019
DOI: 10.1038/S41598-019-50314-W
Abstract: Initial research on the spread of cane toads ( Rhinella marina ) through tropical Australia reported a high incidence of spinal arthritis (spondylosis) in toads at the invasion front (where toads disperse rapidly), but not in areas colonized earlier (where toads are more sedentary). The idea that spondylosis was a cost of rapid dispersal was challenged by wider spatial s ling which linked rates of spondylosis to hot (tropical) climates rather than to dispersal rates. Here, the authors of these competing interpretations collaborate to reinterpret the data. Our reanalysis supports both previous hypotheses rates of spondylosis are higher in populations established by fast-dispersing toads, and are higher in tropical than in temperate environments they are also higher in larger toads. The functional reason for climatic effects is unclear, but might involve effects on the soil-living bacteria involved in the induction of spondylosis and/or may reflect higher movement (as opposed to dispersal) or more pronounced dry-season aggregation rates of toads in tropical conditions.
Measuring the Prevalence of Current, Severe Symptoms of Mental Health Problems in a Canadian Correctional Population
Publisher: SAGE Publications
Date: 20-10-2013
Abstract: This study measured the prevalence of current, severe symptoms of a mental health problem in an adult population of inmates in Ontario, Canada. The Resident Assessment Instrument–Mental Health was used to measure the prevalence of symptoms among a s le of 522 inmates. Propensity score weighting was used to adjust for nonrandom selection into the s le. Prevalence estimates were derived for the total inmate population, remand and sentenced, males and females, and Aboriginal and non-Aboriginal inmates. It is estimated that 41.1% of Ontario inmates will have at least one current, severe symptom of a mental health problem of this group, 13.0%, will evidence two or more symptoms. The number of symptoms is strongly associated with presence of a psychiatric diagnosis and level of mental health care needs. Female (35.1%) and Aboriginal (18.7%) inmates are more likely to demonstrate two or more current, severe symptoms. Greater efforts must be made to bridge the gap between correctional and mental health care systems to ensure inmates in correctional facilities can access and receive appropriate mental health care services.
Using a natural population collapse of an invasive species to assess the benefits of invader control for native species
Publisher: Springer Science and Business Media LLC
Date: 29-05-2019
Maladaptive traits in invasive species: in Australia, cane toads are more vulnerable to predatory ants than are native frogs
Publisher: Wiley
Date: 21-05-2009
Invasion, stress, and spinal arthritis in cane toads
Publisher: Proceedings of the National Academy of Sciences
Date: 06-11-2007
Abstract: The impact of invasive species on bio ersity has attracted considerable study, but impacts of the invasion process on the invaders themselves remain less clear. Invading species encounter conditions different from those in their ancestral habitats and are subject to intense selection for rapid dispersal. The end result may be significant stress on in idual organisms, with consequent health problems. Our studies on invasive cane toads in Australia reveal severe spinal arthritis in ≈10% of large adult toads, associated with the same factors (large body size, frequent movement, and relatively long legs) that have enabled toads to invade so rapidly across the Australian tropics.
Assessing the potential impact of cane toads on Australian snakes
Publisher: Wiley
Date: 12-2003
Male‐biased dispersal in a tropical Australian snake (Stegonotus cucullatus, Colubridae)
Publisher: Wiley
Date: 19-07-2008
DOI: 10.1111/J.1365-294X.2008.03859.X
Abstract: Sex-based differences in dispersal distances can affect critical population parameters such as inbreeding rates and the spatial scale of local adaptation. Males tend to disperse further than females in mammals, whereas the reverse is true for birds too few reptiles have been studied to reveal generalities for that group. Although reptiles are most erse and abundant in the tropics, few tropical reptiles have been studied in this respect. We combine data from a long-term (10-year) mark-recapture study with genetic information (based on nine microsatellite markers) on slatey-grey snakes (Stegonotus cucullatus, Colubridae) in the Australian wet-dry tropics. Males attain larger body sizes than females, and both genetic and mark-recapture data show that males also disperse further than females. Recapture records show that hatchling males dispersed away from their release points whereas hatchling females did not, and adult males moved further than adult females. In the genetic analysis, males contributed less to overall FST and relatedness than did females (F(STm) = 0.0025, F(STf) = 0.0275, P < 0.001 r(m) = 0.0053 r(f) = 0.0550 P < 0.001). Spatial autocorrelation analyses within the largest population revealed a similar pattern, with spatial structuring stronger for females than males. Overall, our genetic analyses not only supported the mark-recapture data, but also extended our insights by revealing occasional long-distance dispersal not detected by the mark-recapture study.
Predators learning to avoid toxic invasive prey: a study on individual variation among free-ranging lizards
Publisher: Brill
Date: 30-09-2020
DOI: 10.1163/1568539X-BJA10040
Abstract: Within all wild populations, in iduals vary in ways that affect their vulnerability to threatening processes. Understanding that variation may clarify mechanisms of population persistence and/or evolution. In Australia, Yellow-spotted Monitors ( Varanus panoptes ), decline by % when toxic Cane Toads ( Rhinella marina ) invade an area. Taste-aversion training (exposing animals to non-lethal toads) can buffer impacts but does pre-existing behavioural variation also influence survival? An in idual’s fate can be predicted from its behaviour during aversion-training trials. Lizards presented with small toads either consumed them, rejected them, or fled. When Cane Toads invaded our study site, mortality was lower in lizards that ‘consumed’ (aversion-trained) than in those that ‘fled’ (untrained), but even lower in lizards that ‘rejected’ toads outright. Thus, animals reluctant to consume toads in trials survived despite never being aversion-trained. In this system, lizard vulnerability is driven by boldness, behavioural responses to novel prey types, and the opportunity to learn aversion.
Diverse aging rates in ectothermic tetrapods provide insights for the evolution of aging and longevity.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 24-06-2022
Abstract: Comparative studies of mortality in the wild are necessary to understand the evolution of aging yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and hibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher ersity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.
Life-history evolution in range-shifting populations
Publisher: Wiley
Date: 06-2010
DOI: 10.1890/09-0910.1
Abstract: Most evolutionary theory does not deal with populations expanding or contracting in space. Invasive species, climate change, epidemics, and the breakdown of dispersal barriers, however, all create populations in this kind of spatial disequilibrium. Importantly, spatial disequilibrium can have important ecological and evolutionary outcomes. During continuous range expansion, for ex le, populations on the expanding front experience novel evolutionary pressures because frontal populations are assorted by dispersal ability and have a lower density of conspecifics than do core populations. These conditions favor the evolution of traits that increase rates of dispersal and reproduction. Additionally, lowered density on the expanding front eventually frees populations on the expanding edge from specialist, coevolved enemies, permitting higher investment into traits associated with dispersal and reproduction rather than defense against pathogens. As a result, the process of range expansion drives rapid life-history evolution, and this seems to occur despite ongoing serial founder events that have complex effects on genetic ersity at the expanding front. Traits evolving on the expanding edge are smeared across the landscape as the front moves through, leaving an ephemeral signature of range expansion in the life-history traits of a species across its newly colonized range. Recent studies suggest that such nonequilibrium processes during recent population history may have contributed to many patterns usually ascribed to evolutionary forces acting in populations at spatial equilibrium.
The fauna fights back
Publisher: Royal Zoological Society of New South Wales
Date: 02-02-2021
DOI: 10.7882/AZ.2021.002
Abstract: We report two cases of Cane Toads Rhinella marina being killed by Australasian Giant Centipedes Ethmostigmus rubripes in the Northern Territory. At 1730 h on 12 November 2020, a centipede was found attacking a subadult Cane Toad near Larrimah, Northern Territory. At 2015 h on 26 April 2005, near Humpty Doo, a centipede that was seized by a subadult Cane Toad retaliated and killed its attacker (but did not consume it). These observations reinforce the fact that, contrary to popular opinion, Cane Toads are vulnerable to many species of native predators in Australia.
Effects of rearing environment and population origin on responses to repeated behavioural trials in cane toads (Rhinella marina)
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.BEPROC.2018.05.001
Abstract: Behavioural responses to repeated trials in captivity can be driven by many factors including rearing environment, population of origin, habituation to captivity/trial conditions and an in idual's behavioural type (e.g., bold versus shy). We tested the effect of rearing environment (captive raised common-garden versus wild-caught) and population origin (range-edge versus range-front) on the responses of invasive cane toads (Rhinella marina) to repeated exploration and risk-taking assays in captivity. We found that behavioural responses to identical assays performed on two occasions were complex and showed few consistent patterns based on rearing environment or population of origin. However, behavioural traits were repeatable across Trial Blocks when all s le populations were grouped together, indicating general consistency in in idual toad behaviour across repeated behavioural assays. Our findings exemplify the complexity and unpredictability of behavioural responses and their effects on the repeatability and interpretation of behavioural traits across repeated behavioural assays in captivity. To meaningfully interpret the results from repeated behavioural assays, we need to consider how multiple factors may affect behavioural responses to these tests and importantly, how these responses may affect the repeatability of behavioural traits across time.
Supplemental methods and results from Intergenerational effects of manipulating DNA methylation in the early life of an iconic invader
Publisher: The Royal Society
Date: 2021
Larger Body Size at Metamorphosis Enhances Survival, Growth and Performance of Young Cane Toads (Rhinella marina)
Publisher: Public Library of Science (PLoS)
Date: 29-07-2013
The ecological impact of invasive cane toads on tropical snakes: Field data do not support laboratory-based predictions
Publisher: Wiley
Date: 02-2011
DOI: 10.1890/10-0536.1
Abstract: Predicting which species will be affected by an invasive taxon is critical to developing conservation priorities, but this is a difficult task. A previous study on the impact of invasive cane toads (Bufo marinus) on Australian snakes attempted to predict vulnerability a priori based on the assumptions that any snake species that eats frogs, and is vulnerable to toad toxins, may be at risk from the toad invasion. We used time-series analyses to evaluate the accuracy of that prediction, based on >3600 standardized nocturnal surveys over a 138-month period on 12 species of snakes and lizards on a floodplain in the Australian wet-dry tropics, bracketing the arrival of cane toads at this site. Contrary to prediction, encounter rates with most species were unaffected by toad arrival, and some taxa predicted to be vulnerable to toads increased rather than declined (e.g., death adder Acanthophis praelongus Children's python Antaresia childreni). Indirect positive effects of toad invasion (perhaps mediated by toad-induced mortality of predatory varanid lizards) and stochastic weather events outweighed effects of toad invasion for most snake species. Our study casts doubt on the ability of a priori desktop studies, or short-term field surveys, to predict or document the ecological impact of invasive species.
Factors affecting neonate size variation in northern water snakes, Nerodia sipedon
Publisher: JSTOR
Date: 12-1999
DOI: 10.2307/1565574
Effects of nest temperature and moisture on phenotypic traits of hatchling snakes (Tropidonophis mairii, Colubridae) from tropical Australia
Publisher: Oxford University Press (OUP)
Date: 29-08-2006
Trends in HIV/AIDS morbidity and mortality in Eastern Mediterranean countries, 1990–2015: findings from the Global Burden of Disease 2015 study
Publisher: Springer Science and Business Media LLC
Date: 03-08-2017
New weapons in the toad toolkit: A review of methods to control and mitigate the biodiversity impacts of invasive cane toads (rhinella marina)
Publisher: University of Chicago Press
Date: 06-2017
DOI: 10.1086/692167
Abstract: Our best hope of developing innovative methods to combat invasive species is likely to come from the study of high-profile invaders that have attracted intensive research not only into control, but also basic biology. Here we illustrate that point by reviewing current thinking about novel ways to control one of the world’s most well-studied invasions: that of the cane toad in Australia. Recently developed methods for population suppression include more effective traps based on the toad’s acoustic and pheromonal biology. New tools for containing spread include surveillance technologies (e.g., eDNA s ling and automated call detectors), as well as landscape-level barriers that exploit the toad’s vulnerability to desiccation—a strategy that could be significantly enhanced through the introduction of sedentary, range-core genotypes ahead of the invasion front. New methods to reduce the ecological impacts of toads include conditioned taste aversion in free-ranging predators, gene banking, and targeted gene flow. Lastly, recent advances in gene editing and gene drive technology hold the promise of modifying toad phenotypes in ways that may facilitate control or buffer impact. Synergies between these approaches hold great promise for novel and more effective means to combat the toad invasion and its consequent impacts on bio ersity.
Anthropogenically modified habitats favor bigger and bolder lizards
Publisher: Wiley
Date: 31-01-2021
DOI: 10.1002/ECE3.7124
Stress and immunity at the invasion front: a comparison across cane toad (Rhinella marina) populations
Publisher: Oxford University Press (OUP)
Date: 08-2015
DOI: 10.1111/BIJ.12623
Thermal ecology and sexual size dimorphism in northern water snakes, Nerodia sipedon
Publisher: Wiley
Date: 05-2000
Using Combined Morphological, Allometric and Molecular Approaches to Identify Species of the Genus Raillietiella (Pentastomida)
Publisher: Public Library of Science (PLoS)
Date: 20-09-2011
Disease Exposure and Antifungal Bacteria on Skin of Invasive Cane Toads, Australia
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 09-2019
Repeatability and heritability of reproductive traits in free‐ranging snakes
Publisher: Wiley
Date: 10-10-2006
DOI: 10.1111/J.1420-9101.2006.01256.X
Abstract: The underlying genetic basis of life-history traits in free-ranging animals is critical to the effects of selection on such traits, but logistical constraints mean that such data are rarely available. Our long-term ecological studies on free-ranging oviparous snakes (keelbacks, Tropidonophis mairii (Gray, 1841), Colubridae) on an Australian floodplain provide the first such data for any tropical reptile. All size-corrected reproductive traits (egg mass, clutch size, clutch mass and post-partum maternal mass) were moderately repeatable between pairs of clutches produced by 69 female snakes after intervals of 49-1152 days, perhaps because maternal body condition was similar between clutches. Parent-offspring regression of reproductive traits of 59 pairs of mothers and daughters revealed high heritability for egg mass (h2= 0.73, SE=0.24), whereas heritability for the other three traits was low (< 0.37). The estimated heritability of egg mass may be inflated by maternal effects such as differential allocation of yolk steroids to different-sized eggs. High heritability of egg size may be maintained (rather than eroded by stabilizing selection) because selection acts on a trait (hatchling size) that is determined by the interaction between egg size and incubation substrate rather than by egg size alone. Variation in clutch size was mainly because of environmental factors (h2=0.04), indicating that one component of the trade-off between egg size and clutch size is under much tighter genetic control than the other. Thus, the phenotypic trade-off between egg size and egg number in keelback snakes occurs because each female snake must allocate a finite amount of energy into eggs of a genetically determined size.
Sex and age differences in habitat use by invasive cane toads (Rhinella marina) and a native anuran (Cyclorana australis) in the Australian wet-dry tropics
Publisher: Wiley
Date: 19-08-2015
DOI: 10.1111/AEC.12279
Do invasive cane toads (Chaunus marinus) compete with Australian frogs (Cyclorana australis)?
Publisher: Wiley
Date: 06-11-2007
Climate-driven impacts of prey abundance on the population structure of a tropical aquatic predator
Publisher: Wiley
Date: 2010
Invasion and the evolution of speed in toads
Publisher: Springer Science and Business Media LLC
Date: 02-2006
DOI: 10.1038/439803A
Abstract: Cane toads (Bufo marinus) are large anurans (weighing up to 2 kg) that were introduced to Australia 70 years ago to control insect pests in sugar-cane fields. But the result has been disastrous because the toads are toxic and highly invasive. Here we show that the annual rate of progress of the toad invasion front has increased about fivefold since the toads first arrived we find that toads with longer legs can not only move faster and are the first to arrive in new areas, but also that those at the front have longer legs than toads in older (long-established) populations. The disaster looks set to turn into an ecological nightmare because of the negative effects invasive species can have on native ecosystems over many generations, rates of invasion will be accelerated owing to rapid adaptive change in the invader, with continual 'spatial selection' at the expanding front favouring traits that increase the toads' dispersal.
Using a native predator (the meat ant, Iridomyrmex reburrus) to reduce the abundance of an invasive species (the cane toad, Bufo marinus) in tropical Australia
Publisher: Wiley
Date: 04-2010
Global, regional, and national burden of migraine and tension-type headache, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016
Publisher: Elsevier BV
Date: 11-2018
Gender, Psychiatric Symptomatology, Problem Behaviors and Mental Health Treatment in a Canadian Provincial Correctional Population: Disentangling the Associations between Care and Institutional Control
Publisher: Informa UK Limited
Date: 04-2013
Invasive colonic entamoebiasis in wild cane Toads, Australia
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 08-2018
Beyond size-number trade-offs: clutch size as a maternal effect
Publisher: The Royal Society
Date: 12-03-2009
Abstract: Traditionally, research on life-history traits has viewed the link between clutch size and offspring size as a straightforward linear trade-off the product of these two components is taken as a measure of maternal reproductive output. Investing more per egg results in fewer but larger eggs and, hence, offspring. This simple size–number trade-off has proved attractive to modellers, but our experimental studies on keelback snakes ( Tropidonophis mairii , Colubridae) reveal a more complex relationship between clutch size and offspring size. At constant water availability, the amount of water taken up by a snake egg depends upon the number of adjacent eggs. In turn, water uptake affects hatchling size, and therefore an increase in clutch size directly increases offspring size (and thus fitness under field conditions). This allometric advantage may influence the evolution of reproductive traits such as growth versus reproductive effort, optimal age at female maturation, the body-reserve threshold required to initiate reproduction and nest-site selection (e.g. communal oviposition). The published literature suggests that similar kinds of complex effects of clutch size on offspring viability are widespread in both vertebrates and invertebrates. Our results also challenge conventional experimental methodologies such as split-clutch designs for laboratory incubation studies: by separating an egg from its siblings, we may directly affect offspring size and thus viability.
Foraging tactics of an ambush predator: The effects of substrate attributes on prey availability and predator feeding success
Publisher: Springer Science and Business Media LLC
Date: 17-02-2011
THERMAL AND BEHAVIORAL-RESPONSES TO FEEDING IN FREE-RANGING TURTLES, CHELYDRA-SERPENTINA
Publisher: JSTOR
Date: 09-1991
DOI: 10.2307/1564584
Interacting Impacts of Invasive Plants and Invasive Toads on Native Lizards
Publisher: University of Chicago Press
Date: 03-2012
DOI: 10.1086/664184
Abstract: The ecological impacts of an invasive species may be reduced by prior invasions if selective pressures imposed by earlier events preadapt the native biota to deal with the newer arrival. In northwestern Australia, invasion of the cane toad (Rhinella marina) kills many native predators if they ingest the highly toxic toads. Remarkably, the toads' defensive toxins (bufadienolides) are chemically similar to those of another invasive species: an ornamental plant from Madagascar, Bryophyllum spp. (Crassulaceae, mother-of-millions). Omnivorous lizards (bluetongue skinks, Tiliqua scincoides) are imperiled by the invasion of toads in northwestern Australia, but conspecifics from other areas of the continent (those where exotic plants were introduced and including areas where toads have yet to invade) are less affected because they exhibit higher physiological tolerance of toad toxins (and also of plant toxins). The willingness of captive bluetongues to consume both toads and these plants and the high correlation in the lizards' sensitivity to toad toxins versus plant toxins suggest that exotic plants may have imposed strong selection on the lizards' physiological tolerance of bufadienolides. As a result, populations of lizards from areas previously exposed to these alien plants may be preadapted to deal with the toxins of the more recent anuran invader.
Interacting biocontrol programmes: Invasive cane toads reduce rates of breakdown of cowpats by dung beetles
Publisher: Wiley
Date: 15-03-2013
DOI: 10.1111/AEC.12028
Frogs in the spotlight: a 16-year survey of native frogs and invasive toads on a floodplain in tropical Australia
Publisher: Wiley
Date: 07-06-2016
DOI: 10.1002/ECE3.2237
Invasion history alters the behavioural consequences of immune system activation in cane toads
Publisher: Wiley
Date: 28-02-2018
Abstract: Acute activation of the immune system often initiates a suite of behavioural changes. These "sickness behaviours"-involving lethargy and decreased activity-may be particularly costly on invasion fronts, where evolutionary pressures on dispersal favour in iduals that move large distances. We used a combination of field and laboratory studies to compare sickness behaviours of cane toads from populations differing in invasion history. To do this we stimulated immune system activation by injecting lipopolysaccharide (LPS) to mimic bacterial infection. We predicted that LPS would result in less severe sickness behaviour in toads from range-edge populations because they had undergone selection for rapid and sustained dispersal (activities in conflict with lethargy and decreased activity). Contrary to our prediction, LPS injection caused a greater reduction in dispersal-relevant traits in invasion-front in iduals than in conspecifics from the range-core. Our data suggest that the rapid invasion of cane toads through tropical Australia has seen an evolutionary shift in the magnitude of sickness behaviour elicited by pathogen infection. The increased sickness behaviour among range-edge toads suggests a shift away from pathogen tolerance (seen in range-core populations) towards resistance to pathogen attack. But as a consequence, when pathogens do become successfully established, toads from invasion-front populations may have less capacity to tolerate their ill-effects.
Body size, locomotor speed and antipredator behaviour in a tropical snake (Tropidonophis mairii, colubridae)
Publisher: Wiley
Date: 10-2001
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Related Funding Activities
Integrating Ecoimmunology And Population Ecology To Understand How Tropical Reptiles Deal With Novel Challenges
Start Date: Start date not available
End Date: End date not available
Funder: Australian Research Council
View Funded ActivitySurveying Native Wildlife For A Newly-discovered Lethal Pathogen Carried By Invasive Cane Toads In Australia
Start Date: 2018
End Date: 2019
Funder: American Association of Zoo Veterinarians
View Funded ActivityARC Future Fellowships - Grant ID: FT120100095
Start Date: 10-2012
End Date: 10-2017
Amount: $702,528.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP210102176
Start Date: 02-2021
End Date: 01-2025
Amount: $450,000.00
Funder: Australian Research Council
View Funded Activity