Patterns and biases in climate change research on amphibians and reptiles: a systematic review

Insufficient and biased representation of species geographic responses to climate change

The geographic redistributions of species due to a rapidly changing climate are poised to perturb ecological communities and significantly impact ecosystems and human livelihoods. Effectively managing these biological impacts requires a thorough understanding of the patterns and processes of species geographic range shifts. While substantial recent redistributions have been identified and recognized to vary by taxon, region, and range geometry, there are large gaps and biases in the available evidence. Here, we use the largest compilation of geographic range change observations to date, comprised of 33,016 potential redistributions across 12,009 species, to formally assess within- and cross-species coverage and biases and to motivate future data collection. We find that species coverage varies strongly by taxon and underrepresents species at high and low latitudes. Within species, assessments of potential redistributions came from parts of their geographic range that were highly uneven and non-representative. For most species and taxa, studies were strongly biased toward the colder parts of species' distributions and thus significantly underrepresented populations that might get pushed beyond their maximum temperature limits. Coverage of potential leading and trailing geographic range edges under a changing climate was similarly uneven. Only 8% of studied species were assessed at both high and low latitude and elevation range edges, with most only covered at one edge. This suggests that substantial within-species biases exacerbate the considerable geographic and taxonomic among-species unevenness in evidence. Our results open the door for a more quantitative accounting for existing knowledge biases in climate change ecology and a more informed management and conservation. Our findings offer guidance for future data collection that better addresses information gaps and provides a more effective foundation for managing the biological impacts of climate change.

Effects of warming at embryonic and larval stages on tadpole fitness in high-altitude Rana kukunoris

Global warming may affect the early developmental stages of high-altitude amphibians, thereby influencing their later fitness. Yet, this has been largely unexplored. To investigate whether and how the temperatures experienced by embryonic and larval stages affect their fitness at later developmental stages, we designed two experiments in which the embryos and larvae were treated with three temperatures (24, 18 and 12 °C), respectively. Then, the life history traits of the tadpoles during the metamorphotic climax in all treatments were evaluated, including growth rate, survival rate, morphology, thermal physiology, swimming performance, standard metabolic rate (SMR), oxidative and antioxidative system, and metabolic enzyme activities. The results revealed that elevated temperature accelerated metamorphosis but decreased body size at metamorphosis. Additionally, warming during the embryonic and larval stages decreased the thermal tolerance range and induced increased oxidative stress. Furthermore, high embryonic temperature significantly decreased the hatching success, but had no significant effect on swimming performance and SMR. Warming during larval periods was harmful to the survival and swimming performance of tadpoles. The effect size analysis revealed that the negative impacts of embryonic temperature on certain physiological traits, such as growth and development, survival and swimming performance, were more pronounced than those of larval temperature. Our results highlight the necessity for particular attention to be paid to the early stages of amphibians, notably the embryonic stages when evaluating the impact of global warming on their survival.

Broad-scale pesticide screening finds anticoagulant rodenticide and legacy pesticides in Australian frogs

Pesticide contamination poses a significant threat to non-target wildlife, including amphibians, many of which are already highly threatened. This study assessed the extent of pesticide exposure in dead frogs collected during a mass mortality event across eastern New South Wales, Australia between July 2021 and March 2022. Liver tissue from 77 individual frogs of six species were analysed for >600 legacy and contemporary pesticides, including rodenticides. More than a third (36 %) of the liver samples contained at least one of the following pesticides: brodifacoum, dieldrin, DDE, heptachlor/heptachlor epoxide, fipronil sulfone, and 2-methyl-4-chlorophenoxyacetic acid (MCPA). Brodifacoum, a second-generation anticoagulant rodenticide, was found in four of the six frog species analysed: the eastern banjo frog (Limnodynastes dumerilii), cane toad (Rhinella marina), green tree frog (Litoria caerulea) and Peron's tree frog (Litoria peronii). This is the first report of anticoagulant rodenticide detected in wild amphibians, raising concerns about potential impacts on frogs and extending the list of taxa shown to accumulate rodenticides. Dieldrin, a banned legacy pesticide, was also detected in two species: striped marsh frog (Limnodynastes peronii) and green tree frog (Litoria caerulea). The toxicological effects of these pesticides on frogs are difficult to infer due to limited comparable studies; however, due to the low frequency of detection the presence of these pesticides was not considered a major contributing factor to the mass mortality event. Additional research is needed to investigate the effects of pesticide exposure on amphibians, particularly regarding the impacts of second-generation anticoagulant rodenticides. There is also need for continued monitoring and improved conservation management strategies for the mitigation of the potential threat of pesticide exposure and accumulation in amphibian populations.

Assessing Reptile Conservation Status under Global Climate Change

Global climate change drives variations in species distribution patterns and affects biodiversity, potentially increasing the risk of species extinction. Investigating the potential distribution range of species under future global climate change is crucial for biodiversity conservation and ecosystem management. In this study, we collected distributional data for 5282 reptile species to assess their conservation status based on distributional ranges using species distribution models. Our predictions indicate that the potential distribution ranges for over half of these species are projected to decrease under different scenarios. Under future scenarios with relatively low carbon emissions, the increase in the number of threatened reptiles is significantly lower, highlighting the importance of human efforts. Surprisingly, we identified some endangered species that are projected to expand their distribution ranges, underscoring the potential positive effects of climate change on some special species. Our findings emphasize the increased extinction risk faced by reptile species due to climate change and highlight the urgent need to mitigate the effects of habitat degradation and human activities on their potential distribution in the future.

A standard approach for including climate change responses in IUCN Red List assessments

The International Union for Conservation of Nature (IUCN) Red List is a central tool for extinction risk monitoring and influences global biodiversity policy and action. But, to be effective, it is crucial that it consistently accounts for each driver of extinction. Climate change is rapidly becoming a key extinction driver, but consideration of climate change information remains challenging for the IUCN. Several methods can be used to predict species' future decline, but they often fail to provide estimates of the symptoms of endangerment used by IUCN. We devised a standardized method to measure climate change impact in terms of change in habitat quality to inform criterion A3 on future population reduction. Using terrestrial nonvolant tetrapods as a case study, we measured this impact as the difference between the current and the future species climatic niche, defined based on current and future bioclimatic variables under alternative model algorithms, dispersal scenarios, emission scenarios, and climate models. Our models identified 171 species (13% out of those analyzed) for which their current red-list category could worsen under criterion A3 if they cannot disperse beyond their current range in the future. Categories for 14 species (1.5%) could worsen if maximum dispersal is possible. Although ours is a simulation exercise and not a formal red-list assessment, our results suggest that considering climate change impacts may reduce misclassification and strengthen consistency and comprehensiveness of IUCN Red List assessments.

Acclimation capacity to global warming of amphibians and freshwater fishes: Drivers, patterns, and data limitations

Amphibians and fishes play a central role in shaping the structure and function of freshwater environments. These organisms have a limited capacity to disperse across different habitats and the thermal buffer offered by freshwater systems is small. Understanding determinants and patterns of their physiological sensitivity across life history is, therefore, imperative to predicting the impacts of climate change in freshwater systems. Based on a systematic literature review including 345 experiments with 998 estimates on 96 amphibian (Anura/Caudata) and 93 freshwater fish species (Teleostei), we conducted a quantitative synthesis to explore phylogenetic, ontogenetic, and biogeographic (thermal adaptation) patterns in upper thermal tolerance (CTmax) and thermal acclimation capacity (acclimation response ratio, ARR) as well as the influence of the methodology used to assess these thermal traits using a conditional inference tree analysis. We found globally consistent patterns in CTmax and ARR, with phylogeny (taxa/order), experimental methodology, climatic origin, and life stage as significant determinants of thermal traits. The analysis demonstrated that CTmax does not primarily depend on the climatic origin but on experimental acclimation temperature and duration, and life stage. Higher acclimation temperatures and longer acclimation times led to higher CTmax values, whereby Anuran larvae revealed a higher CTmax than older life stages. The ARR of freshwater fishes was more than twice that of amphibians. Differences in ARR between life stages were not significant. In addition to phylogenetic differences, we found that ARR also depended on acclimation duration, ramping rate, and adaptation to local temperature variability. However, the amount of data on early life stages is too small, methodologically inconsistent, and phylogenetically unbalanced to identify potential life cycle bottlenecks in thermal traits. We, therefore, propose methods to improve the robustness and comparability of CTmax/ARR data across species and life stages, which is crucial for the conservation of freshwater biodiversity under climate change.

Ongoing declines for the world's amphibians in the face of emerging threats

Systematic assessments of species extinction risk at regular intervals are necessary for informing conservation action1,2. Ongoing developments in taxonomy, threatening processes and research further underscore the need for reassessment3,4. Here we report the findings of the second Global Amphibian Assessment, evaluating 8,011 species for the International Union for Conservation of Nature Red List of Threatened Species. We find that amphibians are the most threatened vertebrate class (40.7% of species are globally threatened). The updated Red List Index shows that the status of amphibians is deteriorating globally, particularly for salamanders and in the Neotropics. Disease and habitat loss drove 91% of status deteriorations between 1980 and 2004. Ongoing and projected climate change effects are now of increasing concern, driving 39% of status deteriorations since 2004, followed by habitat loss (37%). Although signs of species recoveries incentivize immediate conservation action, scaled-up investment is urgently needed to reverse the current trends.

Heat stress and amphibian immunity in a time of climate change

As a class of vertebrates, amphibians, are at greater risk for declines or extinctions than any other vertebrate group, including birds and mammals. There are many threats, including habitat destruction, invasive species, overuse by humans, toxic chemicals and emerging diseases. Climate change which brings unpredictable temperature changes and rainfall constitutes an additional threat. Survival of amphibians depends on immune defences functioning well under these combined threats. Here, we review the current state of knowledge of how amphibians respond to some natural stressors, including heat and desiccation stress, and the limited studies of the immune defences under these stressful conditions. In general, the current studies suggest that desiccation and heat stress can activate the hypothalamus pituitary-interrenal axis, with possible suppression of some innate and lymphocyte-mediated responses. Elevated temperatures can alter microbial communities in amphibian skin and gut, resulting in possible dysbiosis that fosters reduced resistance to pathogens. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.

Environmental drivers of tropical forest snake phenology: Insights from citizen science

Museum specimens and citizen science initiatives are valuable sources of information on how anthropogenic activities affect biodiversity and how species respond to rapid global change. Although tropical regions harbor most of the planet's biodiversity, investigations on species' phenological changes are heavily biased toward temperate regions. Such unevenness in phenological research is also taxonomically biased, with reptiles being the least studied group among tetrapod species regarding animal phenology. Herein, we used long-term time-series data to investigate environmentally driven changes in the activity pattern of tropical forest snakes. We gathered natural history collection and citizen science data for 25 snake species (five venomous and 20 non-venomous) from an Atlantic Forest region in southeastern Brazil. Using circular mixed-effects models, we investigate whether snake activity patterns followed the variation in environmental variables over a decade. Our results show that the activity pattern of Atlantic Forest snakes was seasonal and largely driven by average temperature and relative humidity. Since snakes are ectothermic animals, they are particularly sensitive to temperature variations, especially at small scales. Moreover, relative humidity can affect snake's seasonal activities through physiological constraints and/or prey availability. Most specimens were registered during the rainy season, with highly venomous snakes (lanceheads and coral snakes) emerging as the most abundant taxa. We highlight the importance of citizen science and natural history collections in better understanding biodiversity. Furthermore, our data obtained from local collectors underscore the need for environmental education programs and collaboration between researchers and local decision-makers to raise awareness and reduce conflicts between people and snakes in the region.

Bat responses to climate change: a systematic review

Understanding how species respond to climate change is key to informing vulnerability assessments and designing effective conservation strategies, yet research efforts on wildlife responses to climate change fail to deliver a representative overview due to inherent biases. Bats are a species-rich, globally distributed group of organisms that are thought to be particularly sensitive to the effects of climate change because of their high surface-to-volume ratios and low reproductive rates. We systematically reviewed the literature on bat responses to climate change to provide an overview of the current state of knowledge, identify research gaps and biases and highlight future research needs. We found that studies are geographically biased towards Europe, North America and Australia, and temperate and Mediterranean biomes, thus missing a substantial proportion of bat diversity and thermal responses. Less than half of the published studies provide concrete evidence for bat responses to climate change. For over a third of studied bat species, response evidence is only based on predictive species distribution models. Consequently, the most frequently reported responses involve range shifts (57% of species) and changes in patterns of species diversity (26%). Bats showed a variety of responses, including both positive (e.g. range expansion and population increase) and negative responses (range contraction and population decrease), although responses to extreme events were always negative or neutral. Spatial responses varied in their outcome and across families, with almost all taxonomic groups featuring both range expansions and contractions, while demographic responses were strongly biased towards negative outcomes, particularly among Pteropodidae and Molossidae. The commonly used correlative modelling approaches can be applied to many species, but do not provide mechanistic insight into behavioural, physiological, phenological or genetic responses. There was a paucity of experimental studies (26%), and only a small proportion of the 396 bat species covered in the examined studies were studied using long-term and/or experimental approaches (11%), even though they are more informative about the effects of climate change. We emphasise the need for more empirical studies to unravel the multifaceted nature of bats' responses to climate change and the need for standardised study designs that will enable synthesis and meta-analysis of the literature. Finally, we stress the importance of overcoming geographic and taxonomic disparities through strengthening research capacity in the Global South to provide a more comprehensive view of terrestrial biodiversity responses to climate change.

Unraveling global impacts of climate change on amphibians distributions: A life-history and biogeographic-based approach

Climate change can affect species distribution patterns in three different ways: pushing them to disperse to new suitable areas, forcing them to adapt to novel climatic conditions, or driving them to extinction. However, the biological and geographical traits that lead to these different responses remain poorly explored. Here, we evaluated how ecological and biogeographic traits influence amphibians’ response to climate change. We performed a systematic review searching for studies that evaluated the effects of future climate change on amphibian’s distribution. Our research returned 31 articles that projected the distribution of 331 amphibians. Our results demonstrate that species inhabiting an elevation above 515 m will lose a significant portion of their climatically suitable area. We also found that as isothermality increases, the amount of area suitable in response to climate change also increases. Another important discovery was that as the size of the baseline area increases, the greater must be the loss of climatically suitable areas. On the other hand, species with very small areas tend to keep their current climatically suitable area in the future. Furthermore, our results indicate that species that inhabit dry habitats tend to expand their suitable area in response to climate change. This result can be explained by the environmental characteristics of these habitats, which tend to present extreme seasonal climates with well-defined periods of drought and rain. We also found that anurans that inhabit exclusively forests are projected to lose a greater portion of their suitable areas, when compared to species that inhabit both forest and open areas, wetlands, and dry and rupestrian environments. The biogeographical realm also influenced anuran’s range shifts, with Afrotropic and Nearctic species projected to expand their geographical ranges. The assessment of climate change effects on amphibian distribution has been the focus of a growing number of studies. Despite this, some regions and species remain underrepresented. Current literature evaluates about 4% of the 7,477 species of Anura and 8% of the 773 species of Caudata and some regions rich in amphibian species remain severely underrepresented, such as Madagascar. Thus, future studies should focus on regions and taxas that remain underrepresented.

There and back again: A meta-analytical approach on the influence of acclimation and altitude in the upper thermal tolerance of amphibians and reptiles

Realistic predictions about the impacts of climate change onbiodiversity requires gathering ecophysiological data and the critical thermal maxima (CTMax) is the most frequently used index to assess the thermal vulnerability of species. In the present study, we performed a systematic review to understand how acclimation and altitude affect CTMax estimates for amphibian and non-avian reptile species. We retrieved CTMax data for anurans, salamanders, lizards, snakes, and turtles/terrapins. Data allowed to perform a multilevel random effects meta-analysis to answer how acclimation temperature affect CTMax of Anura, Caudata, and Squamata and also meta-regressions to assess the influence of altitude on CTMax of frogs and lizards. Acclimation temperature influenced CTMax estimates of tadpoles, adult anurans, salamanders, and lizards, but not of froglets. In general, the increase in acclimation temperature led to higher CTMax values. Altitudinal bioclimatic gradient had an inverse effect for estimating the CTMax of lizards and anuran amphibians. For lizards, CTMax was positively influenced by the mean temperature of the wettest quarter. For anurans, the relationship is inverse; we recover a trend of decreasing CTMax when max temperature of warmest month and precipitation seasonality increase. There is an urgent need for studies to investigate the thermal tolerance of subsampled groups or even for which we do not have any information such as Gymnophiona, Serpentes, Amphisbaena, and Testudines. Broader phylogenetic coverage is mandatory for more accurate analyses of macroecological and evolutionary patterns for thermal tolerance indices as CTMax.

Reptile research shows new avenues and old challenges for extinction risk modelling

This Primer explores the implications of a new PLOS Biology study that presents an innovative method for estimating extinction risk in reptile species worldwide; this method represents a promising avenue to support Red List assessment, alongside some well-known challenges.

Survival of climate warming through niche shifts: Evidence from frogs on tropical islands

How will organisms cope when forced into warmer-than-preferred thermal environments? This is a key question facing our ability to monitor and manage biota as average annual temperatures increase, and is of particular concern for range-limited terrestrial species unable to track their preferred climatic envelope. Being ectothermic, desiccation prone, and often spatially restricted, island-inhabiting tropical amphibians exemplify this scenario. Pre-Anthropocene case studies of how insular amphibian populations responded to the enforced occupation of warmer-than-ancestral habitats may add a valuable, but currently lacking, perspective. We studied a population of frogs from the Seychelles endemic family Sooglossidae which, due to historic sea-level rise, have been forced to occupy a significantly warmer island (Praslin) than their ancestors and close living relatives. Evidence from thermal activity patterns, bioacoustics, body size distributions, and ancestral state estimations suggest that this population shifted its thermal niche in response to restricted opportunities for elevational dispersal. Relative to conspecifics, Praslin sooglossids also have divergent nuclear genotypes and call characters, a finding consistent with adaptation causing speciation in a novel thermal environment. Using an evolutionary perspective, our study reveals that some tropical amphibians have survived episodes of historic warming without the aid of dispersal and therefore may have the capacity to adapt to the currently warming climate. However, two otherwise co-distributed sooglossid species are absent from Praslin, and the deep evolutionary divergence between the frogs on Praslin and their closest extant relatives (~8 million years) may have allowed for gradual thermal adaptation and speciation. Thus, local extinction is still a likely outcome for tropical frogs experiencing warming climates in the absence of dispersal corridors to thermal refugia.

Natural history predicts patterns of thermal vulnerability in amphibians from the Atlantic Rainforest of Brazil

In the Brazilian Atlantic Rainforest (AF), amphibians (625 species) face habitat degradation leading to stressful thermal conditions that constrain animal activity (e.g., foraging and reproduction). Data on thermal ecology for these species are still scarce. We tested the hypothesis that environmental occupation affects the thermal tolerance of amphibian species more than their phylogenetic relationships. We evaluated patterns of thermal tolerance of 47 amphibian species by assessing critical thermal maxima and warming tolerances, relating these variables with ecological covariates (e.g., adult macro- and microhabitat and site of larval development). We used mean and maximum environmental temperature, ecological covariates, and morphological measurements in the phylogenetic generalized least squares model selection to evaluate which traits better predict thermal tolerance. We did not recover phylogenetic signal under a Brownian model; our results point to a strong association between critical thermal maxima and habitat and development site. Forest species were less tolerant to warm temperatures than open area or generalist species. Species with larvae that develop in lentic environment were more tolerant than those in lotic ones. Thus, species inhabiting forest microclimates are more vulnerable to the synergistic effect of habitat loss and climate change. We use radar charts as a quick evaluation tool for thermal risk diagnoses using aspects of natural history as axes.

The risk of forfeiting the ranges of reptiles under nonrandom and stochastic scenarios of moving climate conditions: a case study for 115 species in China

Revealing the hazard features of forfeiting areal ranges for nonidentical scenarios of shifting climatic conditions is pivotal for the conformation of reptiles to climatic warming. Taking 115 reptiles in China as an example, the indefiniteness and danger of shrinking geographical range for the reptiles under stochastic and nonrandom scenarios of moving climatic situations were inspected via exploiting the scenarios of shifting climatic status associated with the representative concentration pathways, Monte Carlo simulation, and the classifications scheme based on the fuzzy set. For non-stochastic states of altering climatic elements, the richness of 115 reptiles improved in certain sites of northeastern, and western China and dropped in several areas of northern, eastern, central China, and southeastern China: roughly 59-74 reptiles forfeiting less than 20% of their present ranges, roughly 25-34 reptiles narrowing less than 20-40% of their present areal ranges, and roughly 105-111 reptiles inhabited more than 80% of their overall areal ranges. For the random status of shifting climatic elements, the count of reptiles that forfeited the various extent of the present or entire areal ranges descended with raising the eventuality; with a possibility of over 0.6, the count of reptiles that minified less than 20%, 20-40%, 40-60%, 60-80% and over 80% of the present ranges was roughly 28-49, 5-10, 1-3, 0-1 and 13-18, separately; the count of reptiles that inhabited below 20%, 20-40%, 40-60%, 60-80% and more than 80% of the entire real ranges was roughly 0-1, 5-6, 1-5, 0-2 and 35-36, separately. About 30% of 115 reptiles would face disappearance danger in response to moving climate conditions in the absence of adaption steps, and the conformation measures were indispensable for the reptiles that shrunk their areas.

Could climate change benefit invasive snakes? Modelling the potential distribution of the California Kingsnake in the Canary Islands

The interaction between climate change and biological invasions is a global conservation challenge with major consequences for invasive species management. However, our understanding of this interaction has substantial knowledge gaps; this is particularly relevant for invasive snakes on islands because they can be a serious threat to island ecosystems. Here we evaluated the potential influence of climate change on the distribution of invasive snakes on islands, using the invasion of the California kingsnake (Lampropeltis californiae) in Gran Canaria. We analysed the potential distribution of L. californiae under current and future climatic conditions in the Canary Islands, with the underlying hypothesis that the archipelago might be suitable for the species under these climate scenarios. Our results indicate that the Canary Islands are currently highly suitable for the invasive snake, with increased suitability under the climate change scenarios tested here. This study supports the idea that invasive reptiles represent a substantial threat to near-tropical regions, and builds on previous studies suggesting that the menace of invasive reptiles may persist or even be exacerbated by climate change. We suggest future research should continue to fill the knowledge gap regarding invasive reptiles, in particular snakes, to clarify their potential future impacts on global biodiversity.

Vulnerability to global warming of the critically endangered Añelo Sand Dunes Lizard (Liolaemus cuyumhue) from the Monte Desert, Patagonia Argentina

The body temperature of lizards is strongly influenced by the thermal quality of microhabitats, exploiting the favourable environmental temperatures, and avoiding exposure to extreme thermal conditions. For these reasons, reptile populations are considered to be especially vulnerable to changes in environmental temperatures produced by climate change. Here, we study the thermal physiology of the critically endangered Añelo Sand Dunes Lizard (Liolaemus cuyumhue Avila, Morando, Perez and Sites, 2009). We hypothesise that (i) there is a thermal coadaptation between optimal temperature for locomotor performance of L. cuyumhue and its thermal preference; (ii) L. cuyumhue lives in an environment with low thermal quality; and (iii) a rise in environmental temperatures due to global warming will impose a decrement in locomotor speed represented by lower warming tolerance and narrower thermal safety margins, increasing their already high vulnerability. We recorded field body temperatures (T b), preferred body temperatures (T pref), the operative temperature (T e), and the thermal sensitivity of locomotion at different body temperatures. Our results indicate that this lizard is not currently under environmental stress or exceeding its thermal limits, but that it is thermoregulating below T pref to avoid overheating, and that an increase in environmental temperature higher than 3.5 °C will strongly affect the use of microhabitats with direct sun exposure.

The insular herpetofauna of Mexico: Composition, conservation, and biogeographic patterns

We compile a Mexican insular herpetofaunal checklist to estimate endemism, conservation status, island threats, net taxonomic turnover among six biogeographic provinces belonging to the Nearctic and Neotropical regions, and the relationships between island area and mainland distance versus species richness. We compile a checklist of insular herpetofaunal through performing a literature and collection review. We define the conservation status according to conservation Mexican law, the Red List of International Union for Conservation of Nature, and Environmental Vulnerability Scores. We determine threat percentages on islands according to the 11 major classes of threats to biodiversity. We estimate the net taxonomic turnover with beta diversity analysis between the Nearctic and Neotropical provinces. The Mexican insular herpetofauna is composed of 18 amphibian species, 204 species with 101 subspecies of reptiles, and 263 taxa in total. Endemism levels are 11.76% in amphibians, 53.57% in reptiles, and 27.91% being insular endemic taxa. Two conservation status systems classify the species at high extinction risk, while the remaining system suggests less concern. However, all systems indicate species lacking assessment. Human activities and exotic alien species are present on 60% of 131 islands. The taxonomic turnover value is high (0.89), with a clear herpetofaunal differentiation between the two biogeographic regions. The species-area and species-mainland distance relationships are positive. Insular herpetofauna faces a high percentage of threats, with the Neotropical provinces more heavily impacted. It is urgent to explore the remaining islands (3,079 islands) and better incorporate insular populations and species in ecological, evolutionary, and systematic studies. In the face of the biodiversity crisis, islands will play a leading role as a model to apply restoration and conservation strategies.

Thermoregulatory strategies of three reclusive lizards (genus Xantusia) from the Baja California peninsula, Mexico, under current and future microenvironmental temperatures

The thermal quality of the habitat is key for the regulation of body temperature in terrestrial ectotherms and, therefore, permits them to carry out their fundamental biological activities. In thermally heterogeneous environments, ectotherms might follow different behavioral or physiological strategies to maintain their body temperature within biologically adequate boundaries, for which they depend on microhabitat selection. These aspects are, thus, relevant in the context of habitat degradation and land-use change. In this study, we characterized the thermal ecology of three lizard species (genus Xantusia) that differ in microhabitat use along the Baja California peninsula, Mexico. We made three predictions: (1) the three species will follow different thermoregulatory strategies according to habitat thermal quality; (2) the thermal requirements and tolerances of these species will match the environmental or microenvironmental thermal conditions; and (3) due to their habitat and range restriction, the species studied will be highly vulnerable to climate change. Our results indicate the existence of thermoregulatory mechanisms in Xantusia to face thermal heterogeneity, including behavioral thermoregulation by choosing different microhabitats, shifts in activity periods, and adaptation to particular high thermal quality microhabitats. Furthermore, despite their association to specific microhabitats and specialized physiology, the studied species will not be adversely affected by climate change, as the increased microenvironmental temperatures will lead to a higher habitat thermal quality and lower costs of thermoregulation. However, we do not discard other indirect adverse effects of climate change not considered in this study.

Temperature and Prey Species Richness Drive the Broad-Scale Distribution of a Generalist Predator

The ongoing climate change and the unprecedented rate of biodiversity loss render the need to accurately project future species distributional patterns more critical than ever. Mounting evidence suggests that not only abiotic factors, but also biotic interactions drive broad-scale distributional patterns. Here, we explored the effect of predator-prey interaction on the predator distribution, using as target species the widespread and generalist grass snake (Natrix natrix). We used ensemble Species Distribution Modeling (SDM) to build a model only with abiotic variables (abiotic model) and a biotic one including prey species richness. Then we projected the future grass snake distribution using a modest emission scenario assuming an unhindered and no dispersal scenario. The two models performed equally well, with temperature and prey species richness emerging as the top drivers of species distribution in the abiotic and biotic models, respectively. In the future, a severe range contraction is anticipated in the case of no dispersal, a likely possibility as reptiles are poor dispersers. If the species can disperse freely, an improbable scenario due to habitat loss and fragmentation, it will lose part of its contemporary distribution, but it will expand northwards.

Thermal biology of Liolaemus scapularis (Iguania:Liolaemidae) from argentinian northwest

Thermal traits knowledge is elemental to forecasting the impacts of environmental change on lizard diversity. Daily and seasonal environmental temperature fluctuations are amplified in desert and semi-desert species. As ectotherms, they can ameliorate physiological constrains through behavioral thermoregulation. Herein, we explored the thermal biology and behavioral related aspects of the endangered sand lizard Liolaemus scapularis and compared it between austral spring and summer seasons. The study was carried out in a north sector of Medanos de Cafayate in the SW of Salta province, Argentina. Mean field-body temperature (Tb) of L. scapularis was 35.72 °C ranging from 29.10 to 41.10 °C. Regression analyzes showed that substrate temperature (Ts) was the parameter that best explained the variability of the Tb. Body temperature in spring was only positively related to Ts, whereas in summer the Tb was positively related to air temperature (Ta). Despite GLMs indicated that the Tb of L. scapularis result statistically unchanged through seasons sampled and sexes, micro-environmental temperatures were different for males and females between sampled seasons. The behavioral thermoregulation trait assessed, sun exposure, revealed that the use of patches with different sun input varied with temperature parameters and between seasons. This behavioral trait seems to have a crucial role in the thermal strategy of these lizards in order to maintain an optimal homeostatic state avoiding overheating; still the Tb recorded for the studied population places Liolaemus scapularis in the upper range for the genus. Our results suggest that the species is an active thermoregulator with a hit gain through sand conduction mainly, a relevant shuttling behavior and seasonal intraspecific shifts.

Effects of mancozeb on heat Shock protein 70 (HSP70) and its relationship with the thermal physiology of Physalaemus henselii (Peters, 1872) tadpoles (Anura: Leptodactylidae)

Negative impacts on amphibians have been reported due to contamination by agrochemicals. However, until now, no study has tested the effect of the fungicide mancozeb (MZ) on thermal tolerance and its relationship with the expression of heat shock proteins (HSPs). MZ is the best-selling broad-spectrum fungicide in the world, which negatively affects non-target organisms. Here, we tested for the first time the effects of MZ on critical thermal maximum (CTmax) and its relationship to the expression of heat shock protein 70 (HSP70) in tadpoles of Physalameus henselii, a colder-adapted species in southernmost of the Neotropical region. A sublethal concentration of 2 mg/L was used. We found that the CTmax of the MZ-treated group was lower than that of the control group. In addition, there was an increase in HSP70 expression in tadpoles exposed to MZ and in tadpoles that underwent heat treatment. However, tadpoles subjected to MZ and heat treatment showed no induced HSP70 protein expression. Our results demonstrated that sublethal doses of the fungicide MZ negatively affected the thermal physiology and heat shock protein expression in tadpoles of P. henselii by inducing an increase in HSP70 concentration and by reducing the critical CTmax supported by tadpoles. It is important to understand the relationship between environmental contamination and physiological thermal limits in our current scenario of high rates of habitat conversion associated with unrestricted use of agrochemicals, as well as the challenging environmental changes induced by global warming.

How will climate change impact fossorial lizard species? Two examples in the Baja California Peninsula

Global climate change and the associated erosion of habitat suitability are pervasive threats to biodiversity. It is critical to identify specific stressors to assess a species vulnerability to extinction, especially in species with distinctive natural histories. Here, we present a combination of field, laboratory, and modeling approaches to evaluate the potential consequences of climate change on two endemic, fossorial lizards species (Anniella geronimensis and Bipes biporus) from Baja California, Mexico. We also include soil type in our models to refine the suitable areas using our mechanistic models. Results suggest that both species are at high risk of extinction by global climate change based on the thermal habitat suitability. The forecast for species persistence is most grave under the RCP8.5 scenario. On the one hand, suitable habitat for A. geronimensis diminishes at its southern distribution, but potential suitable expands towards the north. On the other hand, the suitable habitat for B. biporus will contract significantly with a concomitant reduction in its potential distribution. Because both species have low mobility and are restricted to low elevation, the potential for elevational and latitudinal dispersal to mitigate extinction risk along the Baja California Peninsula is unlikely. In addition each species has specialized thermal requirements (i.e., stenothermic) and soil type preferences to which they are adapted. Our ecophysiological models in combination with the type of soil are fundamental in developing conservation strategies.

Impact of various ecological parameters on the life-history characteristics of Bufotes viridis sitibundus from Turkey

In this study, we used the skeletochronology method to estimate various growth parameters, such as age structure, minimum and maximum life span, age of sexual maturity, and the relationship between body size and weight of eight different populations of the variable toad, Bufotes viridis sitibundus, in Turkey. Further, we determined the relationship between these parameters and ecologic factors using the partial Mantel test. A significant difference was found among the populations with respect to age, body size, and body weight in both males and females. On average, the maximum life span was recorded as 10 years for males and 11 years for females. In the studied populations, the average age of sexual maturity ranged between 2 and 4 years for both sexes. Sexual dimorphism in terms of snout-vent length (SVL) was not observed between males and females in all the populations. Toads from the higher altitudes tended to be significantly larger, older, and heavier than those from lower altitudes. We concluded that altitude and temperature have an impact on the growth rate, body size, and body mass.

ACDC, a global database of amphibian cytochrome-b sequences using reproducible curation for GenBank records

Genetic data are a crucial and exponentially growing resource across all biological sciences, yet curated databases are scarce. The widespread occurrence of sequence and (meta)data errors in public repositories calls for comprehensive improvements of curation protocols leading to robust research and downstream analyses. We collated and curated all available GenBank cytochrome-b sequences for amphibians, a benchmark marker in this globally declining vertebrate clade. The Amphibia's Curated Database of Cytochrome-b (ACDC) consists of 36,514 sequences representing 2,309 species from 398 genera (median = 2 with 50% interquartile ranges of 1-7 species/genus). We updated the taxonomic identity of >4,800 sequences (ca. 13%) and found 2,359 (6%) conflicting sequences with 84% of the errors originating from taxonomic misidentifications. The database (accessible at https://doi.org/10.6084/m9.figshare.9944759 ) also includes an R script to replicate our study for other loci and taxonomic groups. We provide recommendations to improve genetic-data quality in public repositories and flag species for which there is a need for taxonomic refinement in the face of increased rate of amphibian extinctions in the Anthropocene.

¿QUÉ IMPLICACIONES ECOFISIOLÓGICAS TIENE LA ACTIVIDAD NOCTURNA EN REPTILES “DIURNOS”?: UNA REVISIÓN

En esta revisión se resumen por primera vez los estudios publicados que documentan los eventos de actividad nocturna en reptiles considerados exclusivamente como diurnos. Asimismo, se describen y discuten sus implicaciones ecofisiológicas en ambientes tropicales y de altas latitudes desde la perspectiva de los intervalos óptimos de temperatura de actividad, umbrales de tolerancia, periodo de actividad, catemeralidad, hipotermia voluntaria y su importancia ante el cambio climático global. Finalmente, se identifican los aspectos que aún no han sido estudiados a profundidad en este campo de estudio y se proponen nuevas líneas de investigación.

Amphibian responses to livestock use of wetlands: new empirical data and a global review

Pastureland currently occupies 26% of Earth's ice-free land surface. As the global human population continues to increase and developing countries consume more protein-rich diets, the amount of land devoted to livestock grazing will only continue to rise. To mitigate the loss of global biodiversity as a consequence of the ever-expanding amount of land converted from native habitat into pastureland for livestock grazing, an understanding of how livestock impact wildlife is critical. While previous reviews have examined the impact of livestock on a wide variety of taxa, there have been no reviews examining how global livestock grazing affects amphibians. We conducted both an empirical study in south-central Florida examining the impact of cattle on amphibian communities and a quantitative literature review of similar studies on five continents. Our empirical study analyzed amphibian community responses to cattle as both a binary (presence/absence) variable, and as a continuous variable based on cow pie density. Across all analyses, we were unable to find any evidence that cattle affected the amphibian community at our study site. The literature review returned 46 papers that met our criteria for inclusion. Of these studies, 15 found positive effects of livestock on amphibians, 21 found neutral/mixed effects, and 10 found negative effects. Our quantitative analysis of these data indicates that amphibian species that historically occurred in closed-canopy habitats are generally negatively affected by livestock presence. In contrast, open-canopy amphibians are likely to experience positive effects from the presence of livestock, and these positive effects are most likely to occur in locations with cooler climates and/or greater precipitation seasonality. Collectively, our empirical work and literature review demonstrate that under the correct conditions well-managed rangelands are able to support diverse assemblages of amphibians. These rangeland ecosystems may play a critical role in protecting future amphibian biodiversity by serving as an "off-reserve" system to supplement the biodiversity conserved within traditional protected areas.

Drought-induced Suppression of Female Fecundity in a Capital Breeder

Human-induced global climate change is exerting increasingly strong selective pressures on a myriad of fitness traits that affect organisms. These traits, in turn, are influenced by a variety of environmental parameters such as temperature and precipitation, particularly in ectothermic taxa such as amphibians and reptiles. Over the past several decades, severe and prolonged episodes of drought are becoming commonplace throughout North America. Documentation of responses to this environmental crisis, however, is often incomplete, particularly in cryptic species. Here, we investigated reproduction in a population of pitviper snakes (copperhead, Agkistrodon contortrix), a live-bearing capital breeder. This population experienced a severe drought from 2012 through 2016. We tested whether declines in number of progeny were linked to this drought. Decline in total number offspring was significant, but offspring length and mass were unaffected. Reproductive output was positively impacted by precipitation and negatively impacted by high temperatures. We hypothesized that severe declines of prey species (e.g., cicada, amphibians, and small mammals) reduced energy acquisition during drought, negatively impacting reproductive output of the snakes. Support for this view was found using the periodical cicada (Magicicada spp.) as a proxy for prey availability. Various climate simulations, including our own qualitative analysis, predict that drought events will continue unabated throughout the geographic distribution of copperheads which suggests that long-term monitoring of populations are needed to better understand geographic variation in drought resilience and cascading impacts of drought phenomena on ecosystem function.

Seasonal differences in climate change explain a lack of multi-decadal shifts in population characteristics of a pond breeding salamander

There is considerable variation among studies that evaluate how amphibian populations respond to global climate change. We used 23 years of annual survey data to test whether changes in climate have caused predictable shifts in the phenology and population characteristics of adult spotted salamanders (Ambystoma maculatum) during spring breeding migrations. Although we observed year-to-year correlation between seasonal climate variables and salamander population characteristics, there have not been long-term, directional shifts in phenological or population characteristics. Warm winters consistently resulted in early migration dates, but across the 23-year study, there was no overall shift towards warmer winters and thus no advanced migration timing. Warm summers and low variability in summer temperatures were correlated with large salamander body sizes, yet an overall shift towards increasing body sizes was not observed despite rising summer temperatures during the study. This was likely due to the absence of long-term changes of within-year variation in summer temperatures, which was a stronger determinant of body size than summer temperature alone. Climate-induced shifts in population characteristics were thus not observed for this species as long-term changes in important seasonal climate variables were not observed during the 23-years of the study. Different amphibian populations will likely be more resilient to climate change impacts than others, and the probability of amphibians exhibiting long-term population changes will depend on how seasonal climate change interacts with a species’ life history, phenology, and geographic location. Linking a wide range of seasonal climatic conditions to species or population characteristics should thus improve our ability for explaining idiosyncratic responses of species to climate change.

A genome-wide search for local adaptation in a terrestrial-breeding frog reveals vulnerability to climate change

Terrestrial-breeding amphibians are likely to be vulnerable to warming and drying climates, as their embryos require consistent moisture for successful development. Adaptation to environmental change will depend on sufficient genetic variation existing within or between connected populations. Here, we use Single Nucleotide Polymorphism (SNP) data to investigate genome-wide patterns in genetic diversity, gene flow and local adaptation in a terrestrial-breeding frog (Pseudophryne guentheri) subject to a rapidly drying climate and recent habitat fragmentation. The species was sampled across 12 central and range-edge populations (192 samples), and strong genetic structure was apparent, as were high inbreeding coefficients. Populations showed differences in genetic diversity, and one population lost significant genetic diversity in a decade. More than 500 SNP loci were putatively under directional selection, and 413 of these loci were correlated with environmental variables such as temperature, rainfall, evaporation and soil moisture. One locus showed homology to a gene involved in the activation of maturation in Xenopus oocytes, which may facilitate rapid development of embryos in drier climates. The low genetic diversity, strong population structuring and presence of local adaptation revealed in this study shows why management strategies such as targeted gene flow may be necessary to assist isolated populations to adapt to future climates.

Integrative taxonomic reassessment of Odontophrynus populations in Argentina and phylogenetic relationships within Odontophrynidae (Anura)

Amphibians are the most vulnerable vertebrates to biodiversity loss mediated by habitat destruction, climate change and diseases. Informed conservation management requires improving the taxonomy of anurans to assess reliably the species' geographic range. The genus Odontophrynus that is geographically refined to Argentina, Bolivia, Brazil, Uruguay and Paraguay includes currently 12 nominal species with many populations of uncertain taxonomic assignment and subsequently unclear geographic ranges. In this study, we applied integrative taxonomic methods combining molecular (mitochondrial 16S gene), allozyme, morphological and bioacoustic data to delimit species of the genus Odontophrynus sampled from throughout Argentina where most species occur. The combined evidence demonstrates one case of cryptic diversity and another of overestimation of species richness. The populations referred to as O. americanus comprise at least three species. In contrast, O. achalensis and O. barrioi represent junior synonyms of the phenotypically plastic species O. occidentalis. We conclude that each of the four species occurring in Argentina inhabits medium to large areas. The Red List classification is currently "Least Concern". We also propose a phylogenetic hypothesis for the genus and associated genera Macrogenioglottus and Proceratophrys (Odontophrynidae).

Ecophysiology of Amphibians: Information for Best Mechanistic Models

Several amphibian lineages epitomize the faunal biodiversity crises, with numerous reports of population declines and extinctions worldwide. Predicting how such lineages will cope with environmental changes is an urgent challenge for biologists. A promising framework for this involves mechanistic modeling, which integrates organismal ecophysiological features and ecological models as a means to establish causal and consequential relationships of species with their physical environment. Solid frameworks built for other tetrapods (e.g., lizards) have proved successful in this context, but its extension to amphibians requires care. First, the natural history of amphibians is distinct within tetrapods, for it includes a biphasic life cycle that undergoes major habitat transitions and changes in sensitivity to environmental factors. Second, the accumulated data on amphibian ecophysiology is not nearly as expressive, is heavily biased towards adult lifeforms of few non-tropical lineages, and overlook the importance of hydrothermal relationships. Thus, we argue that critical usage and improvement in the available data is essential for enhancing the power of mechanistic modeling from the physiological ecology of amphibians. We highlight the complexity of ecophysiological variables and the need for understanding the natural history of the group under study and indicate directions deemed crucial to attaining steady progress in this field.

Eocene Western European endemic genus Thaumastosaurus: new insights into the question "Are the Ranidae known prior to the Oligocene?"

Background

Amphibians, due to their ecophysiological peculiarities, have a physiology dependent on environmental conditions and sensitively respond to their changes. Here, the oldest record of the genus Thaumastosaurus is described, whose fossil record known exclusively from Western Europe is discussed in the scope of the climatic changes of 33.5-40.5 Ma.

Results

In the present paper, the fossil remains of the genus from three localities in Switzerland (11 samples overall) have been studied and referred to the species Thaumastosaurus bottii. Its stratigraphic distribution has been revised and summarised. The studied localities present the stratigraphically oldest and the most eastern occurrences of the genus Thaumastosaurus. Eocene probable ranids (Ranidae indet./Rana sp./? Rana sp.) from Europe could be referred to Thaumastosaurus.

Discussion

Their first occurrence of ranids most likely coincides with a warm phase of the global climate at 40 Ma, as tropical conditions were prevailing in Europe. As a result of the gradual cooling of the global climate, the tropical conditions in Europe were replaced by drier open habitats towards the latest Eocene at 34 Ma, when the latest occurrence of the European endemic genus Thaumastosaurus is known. Taking the fossil record and the climate evolution of that time into account, it can be concluded that Thaumastosaurus represents one of the groups among the vertebrates that disappeared during the large extinction event at the Eo-Oligocene transition, known as the Grande Coupure. The fossil finds of the genus from the studied localities allow to refer the previously suggested Eocene true frogs to the genus Thaumastosaurus, hereby stating the arrival of the true frog family Ranidae by the genus Pelophylax in Europe from the east at the earliest Oligocene.