Hugo Cayuela, PhD

Research theme 1: Biodemography and senescence

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My research focuses on population ecology and evolutionary demography. I am especially interested in senescence ecology and evolution. I quantify actuarial and reproductive senescence at both intraspecific and interspecific levels. My work aims at identifying the intrinsic and extrinsic factors driving the broad variation of senescence patterns reported within and among species (Figure 1). In particular, I examine how environmental factors such as climate and habitat anthropization (Figure 2) affect actuarial senescence intensity. I also evaluate how functional traits such as protective phenotypes and growth patterns  influence actuarial senescence. Furthermore, I study the contribution of the genetic backgound (e.g., sex chromosomes, mtDNA mutations) to sex-specific differences in actuarial senescence.

 

I mainly investigate questions related to senescence ecology and evolution in ectothermic tetrapods (amphibians and reptiles) that have been neglected for decades by aging studies. These organisms call into question our usual conception of actuarial senescence, which has long been perceived as an inevitable process. Our recent work indicates that nearly 25% of amphibians and reptiles show negligible or even negative actuarial senescence. Moreover, some species of amphibians show an intraspecific variability in the rate of actuarial senescence whose amplitude is almost as large as that observed in mammals as a whole. Ectothermic tetrapods thus impose new challenges for the study of aging while offering us an excellent opportunity to develop our knowledge of the mechanisms shaping the diversity of mortality patterns in nature.

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I also investigate the demographic mechanisms shaping dynamics and long-term viability of wild populations. In particular, I study how human activities and their impact on natural habitats (e.g., habitat destruction and creation) influence various vital rates including survival, reproduction, and lifetime reproductive success (Figure 2). In addition, I investigate how climate factors (e.g., temperature, precipitation) impact demographic parameters within and among species. I mainly investigate these issues in amphibians (e.g., Bombina variegata, Triturus cristatus), which are highly sensitive to anthropogenic habitat changes and climate because of their physiology and thermobiology. In a applied perspective, amphibians are among the most endangered vertebrates in the world, making them important target for conservation policies.

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To adress biodemographic questions, I use longitudinal (capture-recapture) data collected via long-term individual surveys that I carry out myself or in collaboration with environmental NGO and natural reserves. In addition, the development of international networks of collaborators and large-scale demographic databases is at the heart of my research activities. Our knowledge on the demography and senescence of ectothermic tetrapods was until now strongly constrained by the absence of a global and centralized demographic database. Since 2017, I have been developing the ECTOLIFE database that compiles longitudinal and cross-sectional demographic data of survival, fertility and age (as well as other phenotypic traits such as sex and body size). At present time, ECTOLIFE includes capture-recapture and skeletochronological data from 400 and 500 populations respectively, in almost 300 species of amphibians and reptiles. ECTOLIFE is based on a consortium of 241 collaborators (researchers, wildlife managers) from 29 countries around the world.

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Research theme 2: Dispersal ecology and evolution in spatially structured populations

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I investigate the ultimate and proximal causes of dispersal, and the consequences of this behavior for the dynamics and genetics of spatially structured populations. I study how genotype and phenotype plasticity (including transgenerational plasticity) determine the evolution of dispersal and dispersal-related traits. I examine how genotype and phenotypic traits (e.g., body size and condition, size, age) faciliate or impede dispersal, leading to the emergence of dispersal syndromes. In addition, I analyze how environmental factors such patch characteristics (e.g., area, disturbance) and landscape matrix composition influence the different steps (i.e., emigration, transience, and immigration) of dispersal. Moreover, I examine how dispersal patterns (dispersal rates and kernels) influence gene flow and adaptative processes in spatially structured populations.

 

I address these questions in pond-breeding amphibians (Bombina variegata, Triturus cristatus), social birds (Tetrao urogallus), and protists (Tetrahymena thermophyla). I use an integrative approach combining experimental studies (common garden experiments and behavioral tests in arena), capture-recapture data, and genetic/genomic data. Furthermore, I develop novel capture-recapture models allowing quantifying dispersal, survival, and recapture probabilities in spatio-temporally variable landscapes.

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Research theme 3: Population genomics, adaptation, and genetic bases of life history

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I study the evolutionary forces (i.e., dispersion/migration, selection, mutation and drift) shaping the neutral and adaptive genetic structure of populations. I have a particular interest in the molecular mechanisms involved in adaptation to environmental variations with critical effects on phenotypic and demographic traits. I especially examine how molecular signals of adaptation to temperature and habitat anthropization are associated with variation in life history traits among wild populations. I evaluate the role potentially played by different types of genetic variants (SNPs, CNVs and chromosomal rearrangements) in these adaptive processes (see Figure 3).

I address these issues in ectothermic vertebrates, especially fish (Mallotus villosus) and amphibians (Rana luteiventris, Bombina variegata). I develop integrative approaches combining genetic/genomic data (RAD-seq, genome resequencing), long-term longitudinal data (capture-recapture) and common garden experiments.

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