In vertebrates exhibiting intermittent breeding, breeding activity is a factor of critical importance in capturerecapture studies using data from individually marked animals. Nonbreeders can be absent from locations used by breeders and can be considered "temporary emigrants". We addressed the influence of sex on survival in common toads, Bufo bufo (L., 1758), using the Joly-Seber model and the existance of temporary emigration in male common toads by assessing trap-dependence and by conducting a robust design analysis. We addressed the hypothesis that the probability of the presence of an individual in the study area depends on the presence of the individual the year before (i.e., that transitions between reproductive states are a first-order Markovian process). Results provided support for the hypotheses of random temporary emigration, of sex-specific differences in survival, and of the presence of "transients" in males. Females had intermediate survival compared with the groups of "transients + residents" and "resident" males. Females had lower recapture probability under the Joly-Seber model, which may be interpreted as evidence of lower breeding probability or lower detectability of breeding females. Behaviour may explain this difference in that females may attend ponds for shorter periods. This may be common in species where females aggregate to seek fertilization and lay eggs in locations attended by males and in species with a "resource-based lek" mating system. Résumé :Chez les vertébrés à reproduction intermittente, l'activité reproductrice est un facteur d'importance capitale dans les études de capture-recapture basées sur des données de marquage individuel. Les non-reproducteurs peuvent être absents des zones utilisées par les reproducteurs et peuvent être considérés comme des « émigrants temporaires ». Nous avons étudié chez le crapaud commun, Bufo bufo (L., 1758), l'influence du sexe sur la survie en utilisant le modèle de Jolly-Seber, ainsi que l'émigration temporaire en évaluant la présence d'un effet de la capture ("trapdependence") et en faisant une analyse de type « plan robuste » ("robust design") chez les mâles. Nous avons testé l'hypothèse selon laquelle la probabilité de présence d'un individu dans la zone d'étude dépend du fait qu'il ait été présent l'année précédente (c.-à-d. que la transition entre les états reproductifs est un processus de Markov de premier ordre). Nous avons mis en évidence un effet du sexe sur la survie et démontré l'existence d'émigration temporaire aléatoire et la présence d'individus de passage chez les mâles. La survie des femelles est intermédiaire par rapport à celle des groupes de mâles « de passage + résidents » et de mâles « résidents ». La probabilité de recapture estimée avec le modèle de Jolly-Seber est plus faible chez les femelles, ce qui pourrait indiquer une plus faible probabilité de reproduction ou alors une détectabilité inférieure des reproductrices. Des différences comportementales contribuent peut-être à expliquer ce phénomène : les femelles pour...

Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher diversity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.

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.

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