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Evolutionary theories relating to aging predict that patterns of actuarial and reproductive senescence should be aligned, with a common onset of senescence set at the age of first reproduction. However, a few empirical studies reported asynchrony between actuarial and reproductive senescence. This asynchrony is expected to be particularly pronounced in organisms with indeterminate growth. Yet, this process is still poorly documented due to the lack of long-term demographic data on known-aged individuals. We investigated the asynchrony of actuarial and reproductive senescence in the European whip snake, Hierophis viridiflavus, an oviparous colubrid with indeterminate growth. Using demographic data collected over a 29-year period, we showed that females did not experience any fecundity loss late in life. In contrast, they suffered from an early, severe actuarial senescence. Our findings thus revealed a pronounced asynchrony in actuarial and reproductive senescence processes, a phenomenon that could be widespread across the tree of life.

Copy number variants (CNVs) are a major component of genotypic and phenotypic variation in genomes. To date, our knowledge of genotypic variation and evolution has largely been acquired by means of single nucleotide polymorphism (SNPs) analyses. Until recently, the adaptive role of structural variants (SVs) and particularly that of CNVs has been overlooked in wild populations, partly due to their challenging identification. Here, we document the usefulness of Rapture, a derived reduced-representation shotgun sequencing approach, to detect and investigate copy number variants (CNVs) alongside SNPs in American lobster (Homarus americanus) populations. We conducted a comparative study to examine the potential role of SNPs and CNVs in local adaptation by sequencing 1,141 lobsters from 21 sampling sites within the southern Gulf of St. Lawrence, which experiences the highest yearly thermal variance of the Canadian marine coastal waters. Our results demonstrated that CNVs accounts for higher genetic differentiation than SNP markers. Contrary to SNPs, for which no significant genetic-environment association was found, 48 CNV candidates were significantly associated with the annual variance of sea surface temperature, leading to the genetic clustering of sampling locations despite their geographic separation. Altogether, we provide a strong empirical case that CNVs putatively contribute to local adaptation in marine species and unveil stronger spatial signal of population structure than SNPs. Our study provides the means to study CNVs in non-model species and highlights the importance of considering structural variants alongside SNPs to enhance our understanding of ecological and evolutionary processes shaping adaptive population structure.

International audience; Variation in temperature is known to influence mortality patterns in ectotherms. Even though a few experimental studies on model organisms have reported a positive relationship between temperature and actuarial senescence (i.e., the increase in mortality risk with age), how variation in climate influences the senescence rate across the range of a species is still poorly understood in free-ranging animals. We filled this knowledge gap by investigating the relationships linking senescence rate, adult lifespan, and climatic conditions using long-term capture–recapture data from multiple amphibian populations. We considered two pairs of related anuran species from the Ranidae ( Rana luteiventris and Rana temporaria ) and Bufonidae ( Anaxyrus boreas and Bufo bufo ) families, which diverged more than 100 Mya and are broadly distributed in North America and Europe. Senescence rates were positively associated with mean annual temperature in all species. In addition, lifespan was negatively correlated with mean annual temperature in all species except A. boreas . In both R. luteiventris and A. boreas , mean annual precipitation and human environmental footprint both had negligible effects on senescence rates or lifespans. Overall, our findings demonstrate the critical influence of thermal conditions on mortality patterns across anuran species from temperate regions. In the current context of further global temperature increases predicted by Intergovernmental Panel on Climate Change scenarios, a widespread acceleration of aging in amphibians is expected to occur in the decades to come, which might threaten even more seriously the viability of populations and exacerbate global decline.

Across a species range, multiple sources of environmental heterogeneity, at both small and large scales, create complex landscapes of selection, which may challenge adaptation, particularly when gene flow is high. One key to multidimensional adaptation may reside in the heterogeneity of recombination along the genome. Structural variants, like chromosomal inversions, reduce recombination, increasing linkage disequilibrium among loci at a potentially massive scale. In this study, we examined how chromosomal inversions shape genetic variation across a species range, and ask how their contribution to adaptation in the face of gene flow varies across geographic scales. We sampled the seaweed flyCoelopa frigidaalong a bioclimatic gradient stretching across 10° of latitude, a salinity gradient and a range of heterogeneous, patchy habitats. We generated a chromosome-level genome assembly to analyse 1,446 low-coverage whole genomes collected along those gradients. We found several large non-recombining genomic regions, including putative inversions. In contrast to the collinear regions, inversions and low recombining regions differentiated populations more strongly, either along an ecogeographic cline or at a fine-grained scale. These genomic regions were associated with environmental factors and adaptive phenotypes, albeit with contrasting patterns. Altogether, our results highlight the importance of recombination in shaping adaptation to environmental heterogeneity at local and large scales.

Kin selection and dispersal play a critical role in the evolution of cooperative breeding systems. Limited dispersal dramatically increases relatedness in spatially structured populations (population viscosity), with the result that neighbours tend to be genealogical relatives. Yet the increase in neighbours’ performance through altruistic interaction may also result in habitat saturation and thus exacerbate local competition between kin. Our goal was to detect the footprint of kin selection and competition by examining the spatial structure of relatedness and by comparing non-effective and effective dispersal in a population of a lekking bird,Tetrao urogallus. For this purpose, we analysed capture–recapture and genetic data collected over a 6-year period on a spatially structured population ofT. urogallusin France. Our findings revealed a strong spatial structure of relatedness in males. They also indicated that the population viscosity allowed male cooperation through two non-exclusive mechanisms. First, at their first lek attendance, males aggregate in a lek composed of relatives. Second, the distance corresponding to non-effective dispersal dramatically outweighed effective dispersal distance, which suggests that dispersers incur high post-settlement costs. These two mechanisms result in strong population genetic structuring in males. In females, our findings revealed a lower level of spatial structure of relatedness and genetic structure in respect to males. Additionally, non-effective dispersal and effective dispersal distances in females were highly similar, which suggests limited post-settlement costs. These results indicate that kin-dependent dispersal decisions and costs are factors driving the evolution of cooperative courtship and have a genetic footprint in wild populations.

Life‐history theory states that, during the lifetime of an individual, resources are allocated to either somatic maintenance or reproduction. Resource allocation tradeoffs determine the evolution and ecology of life‐history strategies and determine an organisms’ position along the fast–slow continuum. Theory predicts that environmental stochasticity is an important driver of resource allocation and therefore life‐history evolution. Highly stochastic environments are expected to increase uncertainty in reproductive success and select for iteroparity and a slowing down of the life history. To date, most empirical studies have used comparisons among species to examine these theoretical predictions. By contrast, few have investigated how environmental stochasticity affects life‐history strategies at the intraspecific level. In this study, we examined how variation in breeding site stochasticity (among‐year variability in pond volume and hydroperiod) promotes the co‐occurrence of different life‐history strategies in a spatially structured population, and determines life‐history position along the fast–slow continuum in the yellow‐bellied toad Bombina variegata. We collected mark–recapture data from a metapopulation and used multievent capture–recapture models to estimate survival, recruitment and breeding probabilities. We found higher survival and longer lifespans in populations inhabiting variable sites compared to those breeding in stable ones. In addition, probabilities of recruitment and skipping a breeding event were higher in variable sites. The temporal variance of survival and recruitment probabilities, as well as the probability to skip breeding, was higher in variable sites. Taken together, these findings indicate that populations breeding in variable sites experienced a slowing down of the life‐history. Our study thus revealed similarities in the macroevolutionary and microevolutionary processes shaping life‐history evolution.

Dispersal is a central mechanism in ecology and evolution. Dispersal evolution is driven by a trade-off between costs and benefits, which is influenced by inter-individual variability and local environmental conditions (context-dependent dispersal). Many studies have investigated how dispersal decisions may be influenced by environmental factors, including density, predation, and interspecific competition. Yet few have attempted to examine how habitat disturbance may affect the dispersal process in spatially structured populations. In early successional species, one might expect individuals to adjust their dispersal decisions based on two main factors that potentially have an influence on reproductive success: patch size and the level of patch disturbance. In this study, we examined how these two factors affect breeding success and dispersal decisions in an early successional amphibian, the yellow-bellied toad (Bombina variegata). To this end, we used capture–recapture data collected on a spatially structured population occupying 28 breeding patches. We took advantage of recent developments in multievent capture–recapture models to detect signs of context-dependent dispersal. The results revealed that the probability of successful reproduction and the number of newly metamorphosed individuals increased with both the size and the proportion of disturbance of a patch. In addition, our results showed that the factors affecting breeding success also influenced breeding dispersal probability. Large patch size negatively influenced emigration probability; in contrast, it positively influenced immigration probability. Equally, higher disturbance (in terms of the proportion of the patch’s surface area disturbed each year) had a strong negative influence on emigration probability and slightly positively affected immigration probability. These findings strongly suggest that individuals make context-dependent dispersal decisions, adjusted to maximize future fitness prospects in a patch, allowing them to better cope with rapid changes in environmental conditions resulting from the ecological succession process. This opens new areas of potential research into the role of dispersal in organism specialization along an ecological succession gradient.

Temperature is a critical driver of ectotherm life-history strategies, whereby a warmer environment is associated with increased growth, reduced longevity and accelerated senescence. Increasing evidence indicates that thermal adaptation may underlie such life-history shifts in wild populations. Single nucleotide polymorphisms (SNPs) and copy number variants (CNVs) can help uncover the molecular mechanisms of temperature-driven variation in growth, longevity and senescence. However, our understanding of these mechanisms is still limited, which reduces our ability to predict the response of non-model ectotherms to global temperature change. In this study, we examined the potential role of thermal adaptation in clinal shifts of life-history traits (i.e. life span, senescence rate and recruitment) in the Columbia spotted frog Rana luteiventris along a broad temperature gradient in the western United States. We took advantage of extensive capture-recapture datasets of 20,033 marked individuals from eight populations surveyed annually for 14-18 years to examine how mean annual temperature and precipitation influenced demographic parameters (i.e. adult survival, life span, senescence rate, recruitment and population growth). After showing that temperature was the main climatic predictor influencing demography, we used RAD-seq data (50,829 SNPs and 6,599 putative CNVs) generated for 352 individuals from 31 breeding sites to identify the genomic signatures of thermal adaptation. Our results showed that temperature was negatively associated with annual adult survival and reproductive life span and positively associated with senescence rate. By contrast, recruitment increased with temperature, promoting the long-term viability of most populations. These temperature-dependent demographic changes were associated with strong genomic signatures of thermal adaptation. We identified 148 SNP candidates associated with temperature including three SNPs located within protein-coding genes regulating resistance to cold and hypoxia, immunity and reproduction in ranids. We also identified 39 CNV candidates (including within 38 transposable elements) for which normalized read depth was associated with temperature. Our study indicates that both SNPs and structural variants are associated with temperature and could eventually be found to play a functional role in clinal shifts in senescence rate and life-history strategies in R. luteiventris. These results highlight the potential role of different sources of molecular variation in the response of ectotherms to environmental temperature variation in the context of global warming.

The interplay between recombination rate, genetic drift and selection modulates variation in genome-wide ancestry. Understanding the selective processes at play is of prime importance toward predicting potential beneficial or negative effects of supplementation with domestic strains (i.e., human-introduced strains). In a system of lacustrine populations supplemented with a single domestic strain, we documented how population genetic diversity and stocking intensity produced lake-specific patterns of domestic ancestry by taking the species’ local recombination rate into consideration. We used 552 Brook Charr (Salvelinus fontinalis) from 22 small lacustrine populations, genotyped at ~32,400 mapped SNPs. We observed highly variable patterns of domestic ancestry between each of the 22 populations without any consistency in introgression patterns of the domestic ancestry. Our results suggest that such lake-specific ancestry patterns were mainly due to variable associative overdominance (AOD) effects among populations (i.e., potential positive effects due to the masking of possible deleterious alleles in low recombining regions). Signatures of AOD effects were also emphasized by highly variable patterns of genetic diversity among and within lakes, potentially driven by predominant genetic drift in those small isolated populations. Local negative effects such as negative epistasis (i.e., potential genetic incompatibilities between the native and the introduced population) potentially reflecting precursory signs of outbreeding depression were also observed at a chromosomal scale. Consequently, in order to improve conservation practices and management strategies, it became necessary to assess the consequences of supplementation at the population level by taking into account both genetic diversity and stocking intensity when available.

Aim When modelling future or past geographic distributions of a species, attention should be paid to the possible differentiated responses to climate changes between lineages. Dispersal also plays an important role in the capacity of species to track suitable climate, which is particularly relevant for amphibians with limited dispersal ability. In this study, we included different lineages and dispersal distances into species distribution models to make them more biologically relevant in face of climate change scenarios. Location Europe. Taxa Bombina variegata and its lineages. Methods Using MaxEnt, we fitted correlative niche models for B. variegata lineages and also for the species level (B. variegata sensu lato) that we projected under Last Glacial Maximum (LGM) and future climate scenarios (RCP2.6, RCP8.5). A comparison of projections was conducted considering both unlimited and limited dispersal abilities. Results We found that the B. variegata lineages differed in their bioclimatic niches. In general, models run without discriminating the lineages showed reduced suitable areas compared to models run at each lineage, especially those for B. variegata pachypus and B. variegata scabra (southern lineages). Suitable areas identified for the LGM match with the climatic refugia identified in phylogeographic studies. Projections for the mid‐Holocene showed the increase of suitable areas for the lineages B. variegata variegata “Carpathians” and “Western” while they decreased for the southern lineages. In the future (2040–2080), only models under limited dispersal predict the extinction of the Carpathian lineage and a reduction in suitable areas for the other lineages, regardless of periods and scenarios. Main conclusions We demonstrated important shifts in habitat suitability in Europe suggesting range‐shifts about hundreds of kilometres in response to past climate changes. However, rapid and unprecedented changes in suitability are expected in the future due to the accelerated climate warming during the 21st. According to their limited dispersal abilities, the persistence of all B. variegata lineages over time appears uncertain. We further recommend to integrate the intraspecific levels, when available, in modelling process to catch local variations and obtain more accurate results.

When facing an emerging infectious disease of conservation concern, we often have little information on the nature of the host-parasite interaction to inform management decisions. However, it is becoming increasingly clear that the life-history strategies of host species can be predictive of individual- and population-level responses to infectious disease, even without detailed knowledge on the specifics of the host-parasite interaction. Here, we argue that a deeper integration of life-history theory into disease ecology is timely and necessary to improve our capacity to understand, predict and mitigate the impact of endemic and emerging infectious diseases in wild populations. Using wild vertebrates as an example, we show that host life-history characteristics influence host responses to parasitism at different levels of organisation, from individuals to communities. We also highlight knowledge gaps and future directions for the study of life-history and host responses to parasitism. We conclude by illustrating how this theoretical insight can inform the monitoring and control of infectious diseases in wildlife.

Patterns of actuarial senescence can be highly variable among species. Previous comparative analyses revealed that both age at the onset of senescence and rates of senescence are linked to position of a species along the fast–slow life‐history continuum. As there are few long‐term datasets of wild populations with known‐age individuals, intraspecific (i.e. between‐population) variation in senescence is understudied and limited to comparisons of wild and captive populations of the same species, mostly birds and mammals. In this paper, we examined how population position along the fast–slow life‐history continuum affects intraspecific variation in senescence in an amphibian, Bombina variegata. We used capture–recapture data collected in four populations with contrasting life‐history strategies. Senescence trajectories were analysed using Bayesian capture–recapture models. We show that in populations with fast life histories the onset of actuarial senescence was earlier and individuals aged at a faster rate than individuals in populations with slow life histories. Our study provides one of the few empirical examples of among‐population variation in actuarial senescence patterns in the wild and confirms that the fast–slow life‐history gradient is associated with both macroevolutionary and microevolutionary patterns of actuarial senescence.

International audience; There is growing evidence that anthropogenic landscapes can strongly influence the evolution of dispersal, particularly through fragmentation, and may drive organisms into an evolutionary trap by suppressing dispersal. However, the influence on dispersal evolution of anthropogenic variation in habitat patch turnover has so far been largely overlooked. In this study, we examined how human‐driven variation in patch persistence affects dispersal rates and distances, determines dispersal‐related phenotypic specialization, and drives neutral genetic structure in spatially structured populations. We addressed this issue in an amphibian, Bombina variegata, using an integrative approach combining capture–recapture modeling, demographic simulation, common garden experiments, and population genetics. B. variegata reproduces in small ponds that occur either in habitat patches that are persistent (i.e., several decades or more), located in riverine environments with negligible human activity, or in patches that are highly temporary (i.e., a few years), created by logging operations in intensively harvested woodland. Our capture–recapture models revealed that natal and breeding dispersal rates and distances were drastically higher in spatially structured populations (SSPs) in logging environments than in riverine SSPs. Population simulations additionally showed that dispersal costs and benefits drive the fate of logging SSPs, which cannot persist without dispersal. The common garden experiments revealed that toadlets reared in laboratory conditions have morphological and behavioral specialization that depends on their habitat of origin. Toadlets from logging SSPs were found to have higher boldness and exploration propensity than those from riverine SSPs, indicating transgenerationally transmitted dispersal syndromes. We also found contrasting patterns of neutral genetic diversity and gene flow in riverine and logging SSPs, with genetic diversity and effective population size considerably higher in logging than in riverine SSPs. In parallel, intrapatch inbreeding and relatedness levels were lower in logging SSPs. Controlling for the effect of genetic drift and landscape connectivity, gene flow was found to be higher in logging than in riverine SSPs. Taken together, these results indicate that anthropogenic variation in habitat patch turnover may have an effect at least as important as landscape fragmentation on dispersal evolution and the long‐term viability and genetic structure of wild populations.

Dispersal is a central process in ecology and evolution. It strongly influences the dynamics of spatially structured populations and affects evolutionary processes by shaping patterns of gene flow. For these reasons, dispersal has received considerable attention from ecologists, evolutionary biologists, and conservationists. Although it has been studied extensively in taxa such as birds and mammals, much less is known about dispersal in vertebrates with complex life cycles such as pond-breeding amphibians. Over the past two decades, researchers have taken an ever-increasing interest in amphibian dispersal and initiated both basic and applied studies, using a broad range of experimental and observational approaches. This body of research reveals complex dispersal patterns, causations, and syndromes, with dramatic consequences for the demography and genetics of amphibian populations. In this review, our goals are to: redefine and clarify the concept of amphibian dispersal; review current knowledge about the effects of individual (i.e., condition-dependent dispersal) and environmental (i.e., context-dependent dispersal) factors during the three stages of dispersal (i.e., emigration, transience, and immigration); identify the demographic and genetic consequences of dispersal in spatially structured amphibian populations; and propose new research avenues to extend our understanding of amphibian dispersal., Hugo Cayuela warmly thanks the Banting Postdoctoral Fellowships program for its financial support. Further-more, Mathieu Denoël is Research Director at Fonds dela Recherche Scientifique—FNRS. During manuscript writing, Andrés Valenzuela-Sánchez was supported bya FONDECYT de postdoctorado No. 3180107. Any useof trade, firm, and product names is for descriptive purposes only and does not imply endorsement by the U.S.Government. Íñigo Martínez-Solano acknowledges funding by FEDER/Ministerio de Ciencia, Innovación y Universidades—Agencia Estatal de Investigación, Spain,grant CGL2017-83131-P.

Understanding the mechanisms underlying population decline is a critical challenge for conservation biologists. Both deterministic (e.g. habitat loss, fragmentation, and Allee effect) and stochastic (i.e. demographic and environmental stochasticity) demographic processes are involved in population decline. Simultaneously, a decrease of population size has far-reaching consequences for genetics of populations by increasing the risk of inbreeding and the strength of genetic drift, which together inevitably results in a loss of genetic diversity and a reduced effective population size ( $$N_{{\text{e}}}$$ ). These genetic factors may retroactively affect vital rates (a phenomenon coined ‘inbreeding depression’), reduce population growth, and accelerate demographic decline. To date, most studies that have examined the demographic and genetic processes driving the decline of wild populations have neglected their spatial structure. In this study, we examined demographic and genetic factors involved in the decline of a spatially structured population of a lekking bird, the western capercaillie (Tetrao urogallus). To address this issue, we collected capture-recapture and genetic data over a 6-years period in the Vosges Mountains (France). Our study showed that the population of T. urogallus experienced a severe decline between 2010 and 2015. We did not detect any Allee effect on survival and recruitment. By contrast, individuals of both sexes dispersed to avoid small subpopulations, thus suggesting a potential behavioral response to a mate finding Allee effect. In parallel to this demographic decline, the population showed low levels of genetic diversity, high inbreeding and low effective population sizes at both subpopulation and population levels. Despite this, we did not detect evidence of inbreeding depression: neither adult survival nor recruitment were affected by individual inbreeding level. Our study underlines the benefit from combining demographic and genetic approaches to investigate processes that are involved in population decline.

International audience; Dispersal is a central process in ecology and evolution. At the individual level, the three stages of the dispersal process (i.e., emigration, transience and immigration) are affected by complex interactions between phenotypes and environmental factors. Condition‐ and context‐dependent dispersal have far‐reaching consequences, both for the demography and the genetic structuring of natural populations and for adaptive processes. From an applied point of view, dispersal also deeply affects the spatial dynamics of populations and their ability to respond to land‐use changes, habitat degradation and climate change. For these reasons, dispersal has received considerable attention from ecologists and evolutionary biologists. Demographic and genetic methods allow quantifying non‐effective (i.e., followed or not by a successful reproduction) and effective (i.e., with a successful reproduction) dispersal and to investigate how individual and environmental factors affect the different stages of the dispersal process. Over the past decade, demographic and genetic methods designed to quantify dispersal have rapidly evolved but interactions between researchers from the two fields are limited. We here review recent developments in both demographic and genetic methods to study dispersal in wild animal populations. We present their strengths and limits, as well as their applicability depending on study objectives and population characteristics. We propose a unified framework allowing researchers to combine methods and select the more suitable tools to address a broad range of important topics about the ecology and evolution of dispersal and its consequences on animal population dynamics and genetics.

Assessing the immediate and long-term evolutionary consequences of human-mediated hybridization is of major concern for conservation biology. Several studies have documented how selection in interaction with recombination modulates introgression at a genome-wide scale, but few have considered the dynamics of this process within and between chromosomes. Here, we used an exploited freshwater fish, the Brook Charr (Salvelinus fontinalis) for which decades of stocking practices have resulted in admixture between wild populations and an introduced domestic strain to assess both the temporal dynamics and local chromosomal variation in domestic ancestry. We provide a detailed picture of the domestic ancestry patterns across the genome using about 33,000 mapped SNPs genotyped in 611 individuals from 24 supplemented populations. For each lake, we distinguished early and late-generation hybrids using admixture tracts information. To assess the selective outcomes following admixture we then evaluated the relationship between recombination and admixture proportions at three different scales: the whole genome, chromosomes and within 2Mb windows. This allowed us to detect the signature of varied evolutionary mechanisms, as reflected by the finding of genomic regions where the introgression of domestic haplotypes are favored or disfavored. Among these, the main factor modulating local ancestry was likely the presence of deleterious recessive mutations in the wild populations, which can be efficiently hidden to selection in the presence of long admixture tracts. Overall, our results emphasize the relevance of taking into consideration local ancestry information to assess both the temporal and chromosomal variation in local ancestry toward better understanding post-hybridization evolutionary outcomes.

Population genetic theory states that adaptation most frequently occurs from standing genetic variation, which results from the interplay between different evolutionary processes including mutation, chromosomal rearrangements, drift, gene flow and selection. To date, empirical work focusing on the contribution of standing genetic variation to local adaptation in the presence of high gene flow has been limited to a restricted number of study systems. Marine organisms are excellent biological models to address this issue since many species have to cope with variable environmental conditions acting as selective agents despite high dispersal abilities. In this study, we examined how, demographic history, standing genetic variation linked to chromosomal rearrangements and shared polymorphism among glacial lineages contribute to local adaptation to environmental conditions in the marine fish, the capelin (Mallotus villosus). We used a comprehensive dataset of genome-wide single nucleotide polymorphisms (25,904 filtered SNPs) genotyped in 1,359 individuals collected from 31 spawning sites in the northwest Atlantic (North America and Greenland waters). First, we reconstructed the history of divergence among three glacial lineages and showed that they diverged from 3.8 to 1.8 MyA. Depending on the pair of lineages considered, historical demographic modelling provided evidence for divergence with gene flow and secondary contacts, shaped by barriers to gene flow and linked selection. We next identified candidate loci associated with reproductive isolation of these lineages. Given the absence of physical or geographic barriers, we thus propose that these lineages may represent three cryptic species of capelin. Within each of these, our analyses provided evidence for largeNeand high gene flow at both historical and contemporary time scales among spawning sites. Furthermore, we detected a polymorphic chromosomal rearrangement leading to the coexistence of three haplogroups within the Northwest Atlantic lineage, but absent in the other two clades. Genotype-environment associations revealed molecular signatures of local adaptation to environmental conditions prevailing at spawning sites. Altogether, our study shows that standing genetic variation associated with both chromosomal rearrangements and ancestral polymorphism contribute to local adaptation in the presence of high gene flow.

Gene flow has tremendous importance for local adaptation, by influencing the fate of de novo mutations, maintaining standing genetic variation and driving adaptive introgression. Furthermore, structural variation as chromosomal rearrangements may facilitate adaptation despite high gene flow. However, our understanding of the evolutionary mechanisms impending or favouring local adaptation in the presence of gene flow is still limited to a restricted number of study systems. In this study, we examined how demographic history, shared ancestral polymorphism, and gene flow among glacial lineages contribute to local adaptation to sea conditions in a marine fish, the capelin (Mallotus villosus). We first assembled a 490-Mbp draft genome of M. villosus to map our RAD sequence reads. Then, we used a large data set of genome-wide single nucleotide polymorphisms (25,904 filtered SNPs) genotyped in 1,310 individuals collected from 31 spawning sites in the northwest Atlantic. We reconstructed the history of divergence among three glacial lineages and showed that they probably diverged from 3.8 to 1.8 million years ago and experienced secondary contacts. Within each lineage, our analyses provided evidence for large Ne and high gene flow among spawning sites. Within the Northwest Atlantic lineage, we detected a polymorphic chromosomal rearrangement leading to the occurrence of three haplogroups. Genotype-environment associations revealed molecular signatures of local adaptation to environmental conditions prevailing at spawning sites. Our study also suggests that both shared polymorphisms among lineages, resulting from standing genetic variation or introgression, and chromosomal rearrangements may contribute to local adaptation in the presence of high gene flow.

Actuarial senescence appears to be a common process, and senescence patterns are highly variable across the tree of life. To date, studies on animal senescence have largely focused on model species, such as as fruit flies, humans and a few other endotherms. In contrast, our knowledge about ageing remains fragmentary in ectotherm vertebrates, such as reptiles. Here, we examined life history and age-dependent mortality patterns in three tropical tortoises (Kinixys erosa, Kinixys homeana and Kinixys nogueyi) and snakes (Bitis gabonica, Bitis nasicornis and Causus maculatus). Our study revealed that tortoises of the genus Kinixys had a higher survival and a lower recruitment than snakes of the genera Bitis and Causus, indicating a slower life history. Furthermore, we confirmed that survival decreased more slowly with age in tortoises than in snakes. In addition, we highlighted contrasting patterns of age-dependent mortality among the three genera. In Kinixys, the relationship between mortality rate and age was positive and linear, suggesting gradual senescence over tortoise lifetime. In contrast, the relationship between mortality rate and age was negative and sharp in Bitis and Causus, possibly owing to a ‘negative senescence’. Our study is one of the few to have examined and compared the demography and age-dependent mortality patterns of tropical reptiles. Among other things, our results suggest that although negative senescence has never been reported in endotherm vertebrates, it could be a common phenomenon in ectotherms.

International audience; Dispersal is a key process in ecology and evolution. Both theoretical and empirical evidence in actively dispersing organisms support the general notion that the use of nearly straight dispersal paths is a highly ef␣cient way to maximize dispersal success in heterogenous landscapes. In homogeneous landscapes, in contrast, the bene␣ts of a straighter dispersal path could be outweighed by an increase in risk costs, favouring the evolution of tortuous dispersal paths resulting in a relatively slow dispersal. Empirical support for this theoretical prediction, however, has remained elusive. To explore this theoretical pre- diction, we studied the movement behaviour of the southern Darwin's frog, Rhinoderma darwinii, a fully terrestrial amphibian inhabiting a highly homogeneous environment (i.e. South American temperate forest). Using spatial captureerecapture data collected over a 4-year period in wild populations, in combination with statistical and simulation modelling, we found evidence of a slow natal dispersal lasting one year or more. In contrast, adults exhibited high site ␣delity, having a median annual displacement of 3.64 m. A correlated random walk model produced synthetic distributions of juvenile annual displacement that were nearly identical to the empirical data, suggesting that a plausible explanation of juvenile dispersal is the use of routine movements (with high path tortuosity) over short temporal scales (

International audience; 1. Understanding the mechanisms that regulate the dynamics of spatially structured populations (SSP) is a critical challenge for ecologists and conservation managers. Internal population processes such as births and deaths occur at a local level, while external processes such as dispersal take place at an inter-population level. At both levels, density dependence is expected to play a critical role. At a patch scale, demographic traits (e.g., survival, breeding success) and the population growth rate can be influenced by density either negatively (e.g., competition effect) or positively (e.g., Allee effects). At the scale of an SSP, although positive density-dependent dispersal has been widely reported, an increasing number of studies have highlighted negative density-dependent dispersal. 2. While many studies have investigated the effects of density on population growth or on dispersal, few have simultaneously examined density-dependent effects at the scale of both the local population and the entire SSP. In this study, we examine how density is related to demographic processes at both the pond level (survival and population growth) and the SSP level (between-pond dispersal) in a pondbreeding amphibian, the great crested newt (Triturus cristatus). The study was based on 20 years of individual capture–recapture (CR) data (from 1996 to 2015) gathered from an SSP made up of 12 experimental ponds (“patches”). 3. We first used a CR multievent model to estimate both survival and dispersal rates in specific ponds as a function of distance between ponds. Then, using a second CR multievent model, we examined whether survival and recapture rates were influenced by population density in a pond. Lastly, we used state-space time series models to investigate whether density affected population growth in each pond. 4. Our results found a positive density-dependent effect on survival and a negative density-dependent effect on departure. In addition, the findings indicate that population growth was negatively related to density in all 12 ponds. 5. These results support the hypothesis that in SSPs, density may have multiple and contrasting effects on demographic parameters and growth rates within local populations as well as on dispersal. This study underlines the need to better understand how density dependence may influence potential trade-offs between life-history strategies and life-history stages.

Actuarial senescence (hereafter “senescence”) has been viewed for a long time as an inevitable and uniform process. However, the work on senescence has mainly focused on endotherms (especially mammals) with deterministic growth and low regeneration capacity at adult stages, leading to a strong taxonomic bias in the study of aging. Recent studies have highlighted that senescence could indeed display highly variable trajectory shape that correlates with species life history traits. Slow life histories and indeterminate growth seem to be associated with weak and late senescence. Furthermore, a few studies have suggested that high regenerative abilities could make senescence negligible in several ectotherms (e.g., hydra and salamanders). However, demographic data for species that would allow testing of these hypotheses are scarce and fragmented. Here, we investigated senescence patterns in a group of salamanders (i.e. “true salamanders”) from the Western Palearctic using capture-recapture data and Bayesian modeling. Our results showed that salamanders have slow life histories and that they experience negligible senescence. This pattern was consistent at both intra- and interspecific levels, suggesting that the absence of senescence may be a phylogenetically conserved trait. The regenerative capacities of true salamanders, and urodeles in general, likely explains why these small ectotherms have lifespans similar to that of large endotherms (e.g., ungulates, large birds) and undergo negligible senescence contrary to most amniotes including humans. Our study seriously challenges the idea that senescence is a ubiquitous phenomenon in the living world.

Relocations are increasingly popular among wildlife managers despite sharp debate and low rate of relocation success in vertebrates. In this context, understanding the influence of extrinsic (e.g., relocation design, habitat characteristics) and intrinsic factors (e.g., age and sex) on demographic parameters such as survival that regulate the dynamics of relocated populations is critical to improve relocation protocols and better predict relocation success.We investigated survival in naturally established and relocated populations of yellow-bellied toads (Bombina variegata), an amphibian that was nearly extinct in Belgium by the late 1990s. We quantified survival at three ontogenetic stages (juvenile, subadult, and adult) in the relocated population, the source population, and a control population. In the relocated population, we quantified survival in captive bred individuals and their locally born descendants.We showed that survival at juvenile and subadult stages was relatively similar in all populations. In contrast, relocated adult survival was lower than adult survival in the source and control populations. Despite this, offspring of relocated animals (the next generation, regardless of life stage) survived at similar rates to offspring in the source and control populations. Our simulations revealed that the relocated population was self-sustaining under different scenarios and that the fate (e.g., stability or finite rate of increase) of the simulated populations was highly dependent on the fecundity of relocated adults and their offspring.Policy implications. Our results indicate that survival in relocated individuals is lower than in non-relocated individuals but that this cost (= reduced survival) disappears in the second generation. A finer understanding of how relocation affects demographic processes is an important step in improving relocation success of amphibians and other animals.

International audience; Dispersal is one of the main processes that determine community structure. Individuals make dispersal decisions according to environmental and/or social cues that reflect the fitness prospects in a given patch. The presence and abundance of heterospecifics within the same ecological guild, and/or their breeding success, may act as public information that influences movement decisions. To date, most studies investigating the role of heterospecific attraction have focused on habitat choice, using both experimental and correlational approaches. The present study is the first to examine how long-term variation in heterospecific density in breeding patches may affect dispersal patterns in spatially structured populations. We investigate how the dispersal decisions of the great crested newt (Triturus cristatus) are related to the variable density of two other newt species, the alpine newt (Ichthyosaura alpestris) and the palmate newt (Lissotriton helveticus). To examine this issue, we used capture–recapture data collected in an experimental pond network over a 20-year period. The results revealed that the great crested newt’s dispersal is context dependent and is affected by variation in heterospecific density: individuals were less likely to emigrate from ponds with high heterospecific density and were more likely to immigrate to ponds with high heterospecific density. These findings suggest that individuals adjust their dispersal decisions at least partly based on public information provided by heterospecifics. This mechanism may play a critical role in the dynamics of spatially structured populations and community functioning.

International audience; Dispersal (i.e. movement from a natal or breeding site to another breeding site) is a central process in ecology and evolution as it affects the eco-evolutionary dynam- ics of spatially structured populations. Dispersal evolution is regulated by the bal- ance between costs and benefits, which is influenced by the individual phenotype (i.e. phenotype-dependent dispersal) and environmental factors (i.e. condition-dependent dispersal). Even though these processes have been extensively studied in species with simple life cycles, our knowledge about these mechanisms in organisms displaying complex life cycles remains fragmentary. In fact, little is specifically known about how the interplay between individual and environmental factors may lead to alternative dispersal strategies that, in turn, lead to the coexistence of contrasted site fidelity phe- notypes. In this paper, we examined breeding dispersal in a pond-breeding amphibian, the great crested newt Triturus cristatus, within usual walking distances for a newt. We took advantage of recent developments in multi-event capture–recapture models and used capture–recapture data (946 newts marked) collected in a spatially structured population occupying a large pond network (73 ponds). We showed a high rate of breeding site infidelity (i.e. pond use) and the coexistence of two dispersal phenotypes, namely, a highly pond faithful phenotype and a dispersing phenotype. Individuals that were site faithful at time t – 1 were therefore more likely to remain site faithful at time t. Our results also demonstrated that the probability that individuals belong to one or the other dispersal phenotypes depended on environmental and individual factors. In particular, we highlighted the existence of a dispersal syndrome implying a covariation pattern among dispersal behavior, body size, and survival. Our work opens new research prospects in the evolution of dispersal in organisms displaying complex life cycles and raises interesting questions about the evolutionary pathways that contribute to the diversification of movement strategies in the wild.

International audience; Over the last three decades, climate abnormalities have been reported to be involved in biodiversity decline by affecting population dynamics. A growing number of studies have shown that the North Atlantic Oscillation (NAO) influences the demographic parameters of a wide range of plant and animal taxa in different ways. Life history theory could help to understand these different demographic responses to the NAO. Indeed, theory states that the impact of weather variation on a species’ demographic traits should depend on its position along the fast–slow continuum. In particular, it is expected that NAO would have a higher impact on recruitment than on adult survival in slow species, while the opposite pattern is expected occur in fast species. To test these predictions, we used long-term capture–recapture data- sets (more than 15,000 individuals marked from 1965 to 2015) on different sur- veyed populations of three amphibian species in Western Europe: Triturus cristatus, Bombina variegata, and Salamandra salamandra. Despite substantial intraspecific variation, our study revealed that these three species differ in their position on a slow–fast gradient of pace of life. Our results also suggest that the differences in life history tactics influence amphibian responses to NAO fluctuations: Adult survival was most affected by the NAO in the species with the fastest pace of life (T. cristatus), whereas recruitment was most impacted in species with a slower pace of life (B. variegata and S. salamandra). In the context of climate change, our findings suggest that the capacity of organisms to deal with future changes in NAO values could be closely linked to their position on the fast–slow continuum.

1.The environment of most species is heterogeneous at different spatial and temporal scales; this heterogeneity can have a direct effect on various components of fitness. As a consequence, individual space-use and movement strategies are central issues in ecology and conservation and receive considerable attention from researchers. 2.In the last 30 years, this issue has led to the development of capture–recapture models that allow movement between sites to be quantified, while handling imperfect detection. For studies involving numerous recapture sites in which the emphasis is on dispersal or migration rather than movement between particular sites, Lagrange et al. recently proposed a parsimonious CR multi-event model that contrasts individuals that move and individuals that stay in place, irrespective of the sites involved. 3.In this study, we developed a generalized version of this model to allow survival probability and movement probability to differ for different types of habitat to which the individual sites may be assigned. We investigated the potential of this new parameterization by studying the movements of an amphibian, the yellow-bellied toad (Bombina variegata), in a set of breeding and resting/foraging ponds. 4.Our capture-recapture multi-event model provides a highly flexible tool allowing users to model movements within and between several habitats. This approach can be potentially used to study movement behavior and space-use strategies of a wide range of taxa. This article is protected by copyright. All rights reserved.

International audience; Dispersal is a key process in ecological and evolutionary dynamics. Spatiotemporal vari- ation in habitat availability and characteristics has been suggested to be one of the main cause involved in dispersal evolution and has a strong influence on metapopulation dynamics. In recent dec- ades, the study of dispersal has led to the development of capture–recapture (CR) models that allow movement between sites to be quantified, while handling imperfect detection. For studies involving numerous recapture sites, Lagrange et al. (2014) proposed a multievent CR model that allows disper- sal to be estimated while omitting site identity by distinguishing between individuals that stay and individuals that move. More recently, Cayuela et al. (2017) extended this model to allow survival and dispersal probabilities to differ for the different types of habitat represented by several sites within a study area. Yet in both of these modeling systems, the state of sites is assumed to be static over time, which is not a realistic assumption in dynamic landscapes. For that purpose, we generalized the multi- event CR model proposed by Cayuela et al. (2017) to allow the estimation of dispersal, survival and recapture probabilities when a site may appear or disappear over time (MODEL 1) or when the char- acteristics of a site fluctuate over space and time (MODEL 2). This paper first presents these two new modeling systems, and then provides an illustration of their efficacy and usefulness by applying them to simulated CR data and data collected on two metapopulations of amphibians. MODEL 1 was tested using CR data recorded on a metapopulation of yellow-bellied toads (Bombina variegata). In this first empirical case, we examined whether the drying-out dynamics of ponds and the past dispersal status of an individual might affect dispersal behavior. Our study revealed that the probability of facul- tative dispersal (i.e., from a pond group that remained available/flooded) fluctuated between years and was higher in individuals that had previously dispersed. MODEL 2 was tested using CR data collected on a metapopulation of great crested newts (Triturus cristatus). In this second empirical example, we investigated whether the density of alpine newts (Ichthyosaura alpestris), a potential competitor, might affect the dispersal and survival of the crested newt. Our study revealed that the departure rate was lower in ponds with a high density of heterospecifics than in ponds with a low density of heterospeci- fics at both inter-annual and intra-annual scales. Moreover, annual survival was slightly higher in ponds with a high density of heterospecifics. Overall, our findings indicate that these multievent CR models provide a highly flexible means of modeling dispersal in dynamic landscapes.

International audience; Among the multiple factors involved in the decline of amphibians, competition with alien species remains understudied. In Western Europe, non-native marsh frogs (Pelophylax ridibundus and other sister species) have been widely imported for gastronomic purposes and have then often escaped from captivity. Apart from closely related species, the impact of the subsequent colonization of non-native species on native amphibians is still unknown. In this study, we analysed the response of a threatened species, the yellow-bellied toad (Bombina variegata), faced with the presence of alien frogs in mountain rivers in France. We studied the co-occurrence pattern of the native toad and the alien frog, while taking into account co-dependence of the detection rates in both species. We tested three main scenarios to explain a non-random pond occur- rence for each species and to establish their respective habitat preferenda: (1) a pond-area-dependent scenario, predicting different responses from each species for a given pond size, (2) a fish-dependent scenario, predict- ing different responses from each species given the presence of fish in ponds, and (3) a floodplain-width- dependent scenario, predicting different responses from each species given the geomorphological characteristics of the floodplain. Taking into account site-specific covariates, we concluded that introduced frogs do not currently have an impact on the native population of the yellow-bellied toad.

Species that occur in ephemeral habitats such as temporary waterbodies have evolved specific strategies that allow them to respond to spatial and temporal variations in water availability and quality. Their life-history strategies, involving complex life cycles, have evolved to allow individuals to escape deteriorating environmental conditions when a waterbody dries up. These adaptations have led to the emergence of complex movement behaviour, which might then be expected to affect the spatiotemporal dynamics of reproduction. To date, few empirical studies have investigated how the risks of waterbody drying out affects movement behaviour at the individual level and how movement decisions then shape waterbody occupancy dynamics. In this study, we examined this issue in an endangered amphibian, the yellow-bellied toad (Bombina variegata). For this purpose, we experimentally manipulated waterbody hydroperiod and collected capture-recapture and presence-absence data in 334 waterbodies located in 15 B.variegata populations in the region of Geneva (Switzerland) during a 5-year period (2012-2016). The results of our analyses reveal that the waterbody hydroperiod affects this species' movement behaviour. Adults were less likely to leave waterbodies with a long hydroperiod both intra- and inter-annually. In addition, breeding occupancy strongly depended on a waterbody's hydroperiod. In particular, interannual changes in breeding occurrence were less frequent in waterbodies with a long hydroperiod. Our findings show that the hydroperiod strongly affects ecological processes at different levels, from individuals' movement decisions to waterbody occupancy dynamics. The results demonstrate that adults adjust their movement decisions according to the risk of breeding failure driven by the hydroperiod, which then affects the waterbody occupancy dynamics.

International audience; In many species, females may be particularly selective about the expected direct benefits of choosing a potential mate or the male's genetic contribution to their offspring. Growing evidence suggests that female choosiness can also be influenced, for instance, by local abiotic factors, the social environment or the presence of heterospecifics. In amphibians that breed in highly temporary ponds with limited trophic resources (such as the yellow-bellied toad, Bombina variegata), competition during larval development may have a strong impact on the fitness of offspring. Accordingly, one might expect females to apply hierarchical decision making, balancing intraspecific competition risks during larval growth against the relative indirect benefits associated with the quality of the male. To investigate this issue, we conducted experiments in seminatural enclosures to test whether the preference of yellow-bellied toad females for good call attractiveness (determined by fundamental frequency) is affected by the risk of larval competition within the pond occupied by the callers. Overall, our results showed that females have a preference for low-frequency calls when prior information does not enable them to assess the relative quality of ponds. However, when prior information enables females to unambiguously determine relative pond quality, females appear to apply hierarchical decision making in which the quality of a pond prevails over call cues related to the quality of the male.

When deciding to mate, it is assumed that females choose males bearing genes that will improve the genetic quality of their offspring, which is affected by both additive and nonadditive genetic variation. In this context, a ‘compatible genes’ model has been put forward to explain female mating decisions. According to this model, females are assumed to increase the genetic quality of their offspring by choosing mates on the basis of interactions between maternal and paternal genomes. Yet, this model is mainly supported by empirical data in endotherm vertebrates. Few studies have investigated this issue in terrestrial ectotherms like amphibians. These organisms often live in spatially structured populations characterized by small subpopulations and a high degree of philopatry, leading to striking reduction in gene flow, high genetic drift and relatively high inbreeding levels. In such a situation, one might expect that natural selection should favour mating tactics limiting the risk of inbreeding depression. In this paper, using an experimental approach controlling for the reproductive state of males, we examined how genetic compatibility may affect mating behaviour in an anuran, the yellow-bellied toad, Bombina variegata. First, our analyses confirmed a high degree of inbreeding in the studied population. Yet, we did not find any mating tactic that reduced the risk of inbreeding depression. Contrary to our expectations, males more closely related to the female had the higher mating success. We discuss the ecological and evolutionary implications of these results.

International audience; Dispersal is a central component of life history evolution. An increasing number of studies suggest that spatiotemporally variable environments may promote the evolution of “dispersal syndromes,” consisting of covariation patterns between dispersal and morphologi- cal, physiological, behavioral, and life history traits. At the interspecific scale, the “colonizer syndrome” appears to be one of the most frequently recorded associations between dispersal and life history traits, linking a high dispersal rate, high fecundity, and a short lifespan as sys- tematically combined adaptations in spatiotemporally varying environments. However, few studies have highlighted the existence of a “colonizer syndrome” at the intraspecific scale, and none have investigated how different degrees of habitat stochasticity might shape covariation patterns between dispersal and life history traits. In this study, we examined this issue in free- ranging metapopulations of the yellow-bellied toad (Bombina variegata) using capture–recap- ture data. Combining the results of this study with another recent study, we found that a high dispersal rate, high fecundity, and a short lifespan are associated in metapopulations experi- encing unpredictable environments. In contrast, a very low dispersal rate (close to zero), low fecundity and a long lifespan are associated in metapopulations occupying predictable environ- ments. We discuss these results as well as their demographic and evolutionary consequences.

International audience; Climate is globally changing. In Europe, studies have highlighted an increasing trend in both the frequency and magnitude of droughts. Abrupt changes in the frequency, location, or intensity of extreme heatwaves and droughts can have direct and severe effects on wild populations. Amphibians are the planet's most threatened group of vertebrates, with over 40% of known species considered in decline. To date, researchers have mainly focused on the influence of repeated droughts on species occurrence and community composition; however, evidence of the direct impact of climatic factors on the demographic parameters of amphibians is currently not well documented. Further investigation of this issue is therefore of critical importance in order to optimize local and global wildlife conservation policies in the context of a changing climate. This study used capture-recapture data to investigate the impact of severe drought on the survival and fecundity of a threatened amphibian, the yellow-bellied toad (Bombina variegata, L.), as well as to predict how potential changes in the frequency of droughts might influence the population growth rate. By developing multievent capture-recapture models, we showed that severe drought has a negative impact on fecundity and postmetamorphic survival at different ontogenetic stages. Then, using stochastic matrix population models, we predicted that changes in drought frequency negatively influence the population growth rate, which is a warning sign for population persistence. Direct conservation actions are then proposed to mitigate the detrimental effects of drought on population dynamics.

International audience; Weather fluctuations have been demonstrated to affect demographic traits in many species. In long-lived organisms, their impact on adult survival might be buffered by the evolution of traits that reduce variation in interannual adult survival. For example, skipping breeding is an effective behavioral mechanism that may limit yearly variation in adult survival when harsh weather conditions occur; however, this in turn would likely lead to strong variation in recruitment. Yet, only a few studies to date have examined the impact of weather variation on survival, recruitment and breeding probability simultaneously in different populations of the same species. To fill this gap, we studied the impact of spring temperatures and spring rainfall on survival, on reproductive skipping behavior and on recruitment in five populations of a long-lived amphibian, the yellow-bellied toad (Bombina variegata). Based on capture–recapture data, our findings demonstrate that survival depends on interactions between age, population and weather variation. Varying weather conditions in the spring result in strong variation in the survival of immature toads, whereas they have little effect on adult toads. Breeding probability depends on both the individual’s previous reproductive status and on the weather conditions during the current breeding season, leading to high interannual variation in recruit- ment. Crucially, we found that the impact of weather variation on demographic traits is largely context dependent and may thus differ sharply between populations. Our results suggest that studies predicting the impact of climate change on population dynamics should be taken with caution when the relationship between climate and demo- graphic traits is established using only one population or few populations. We therefore highly recommend further research that includes surveys replicated in a substantial number of populations to account for context-dependent variation in demographic processes.

International audience; Because it modulates the fitness returns of possible options of energy expenditure at each ontogenetic stage, environmental stochasticity is usually considered a selective force in driving or constraining possible life histories. Divergent regimes of envi- ronmental fluctuation experienced by populations are expected to generate differences in the resource allocation schedule between survival and reproductive effort and outputs. To our knowledge, no study has previously examined how different regimes of stochastic variation in environmental conditions could result in changes in both the temporal variation and mean of demographic parameters, which could then lead to intraspecific variation along the slow–fast continuum of life history tactics. To investigate these issues, we used capture–recapture data collected on five populations of a long-lived amphibian (Bombina variegata) experiencing two distinct levels of stochastic environmental variation: (1) constant availability of breeding sites in space and time (predictable environment), and (2) variable spatio-temporal availability of breeding sites (unpredictable environment). We found that female breeding propensity varied more from year to year in unpredictable than in pre- dictable environments. Although females in unpredictable environments produced on average more viable offspring per year, offspring production was more variable between years. Survival at each ontogenetic stage was slightly lower and varied significantly more from year to year in unpredictable environments. Taken together, these results confirm that increased environmental stochasticity can modify the resource allocation schedule between survival and reproductive effort and outputs and may lead to intraspecific variation along the slow–fast continuum of life history tactics.

Amphibians are considered to be the most threatened group of vertebrates. Among the multiple factors involved in their decline, habitat loss and alteration as a result of human activities is a major threat. At the individual level the effects of habitat alteration are potentially multiple, including a range of morphological and physiological responses. Analysing and understanding these responses is therefore a critical challenge for amphibian conservation. We examined the influence of intensive vehicle traffic (motorbikes and trucks on unpaved pathways) on the body size and condition and on the production of glucocorticoids (i.e. corticosterone) in the yellow-bellied toad Bombina variegata. In particular, we tested the hypothesis that intensive vehicle traffic has a negative influence on body size and body condition, and postulated that it also increases corticosterone production. Using morphometric data and saliva samples collected from four populations in France, we found that intensive vehicle traffic is associated with a decrease in body size and body condition in both males and females. Furthermore, our analysis revealed that corticosterone production was lower in both sexes in populations experiencing intensive vehicle traffic. We suggest that measures should be applied to reduce vehicle traffic intensity on unpaved pathways during toad breeding activity. This is critical for B. variegata, for which man-made ruts and residual puddles could mitigate the loss of natural habitats.

International audience; Mate preference was long assumed to be static and open-ended. However, a growing body of evidence actually suggests that the predominant factor in mate choice fluctuates due to the context dependence of the factors involved in sexual selection. In particu- lar, fluctuation in the local environment, the density of individuals, and the presence of heterospecifics can all alter the strength, form, or direction of sexual selection by shaping the fitness costs and benefits of the traits that mediate male–female interactions. Amphibians constitute useful biological models to examine context dependence in sexual selection as the availability of suitable breeding resources may significantly impact the cost–benefit trade-off between mating strategies. Using an experimental approach, we examined how the risk of larval competition in breeding ponds affects pond occupancy, male–male spacing behavior, and spawn- ing decisions in an anuran, the yellow-bellied toad (Bombina variegata). Then, we examined how female mate choice is affected by male body condition and how the risk of larval competition might influence females when choosing a mate. Our results indicate that male pond preference is strongly affected by the presence of conspecific tadpoles. Males preferentially selected ponds free of tadpoles, and spawning mainly occurred in these same ponds. This preference influenced male spacing behavior by enhancing the proximity of competing males when the availability of good-quality sites was experimentally manipulated, which had further significant consequences on females’ choice of mate. The article also discusses the evolutionary causes and consequences of such context- dependent mate choice in amphibians and beyond.

Because of the narrowness of their niches, specialised species are often vulnerable because their populations suffer from fragmentation or low densities. Whatever the causes of their specialization, one might expect micro-habitat selection to be strong within the boundaries of the chosen niche to compensate for the costs linked to habitat constraints (variability of reproductive success due to high larval mortality, habitat fragmentation). We tested this hypothesis by investigating breeding site selection in the yellow-bellied toad (Bombina variegata) in the context of rock pools at riverbanks, which are supposed to be one of the pristine habitats of the species. In this species, breeding habitat use differs markedly from that of other European anurans since spawning takes place in small pools located in the close vicinity of rivers. Such pools experience high risks of drying up and flooding. By measuring 8 habitat variables at 187 rock pools along a 250 m river segment, we show a breeding habitat use based on a preference for pools with large volumes of water provided that they are devoid of alluvia, with a good exposition to sun. By ensuring longer water periods and faster development rates, large volumes and warm water probably reduce the mortality risks due to drying up (within suitable temperature range). This result contributes to understanding the process of niche conservatism (persistence of narrow range on certain dimensions of the niche), which is an important challenge in ecology and conservation biology.