PhD Thesis Title:
Demographic resilience and persistence of ectotherm populations under climate warming
Supervision:
Co-supervisors: Hugo Cayuela (University of Rennes, France), Daniel Noble (Australian National University, Australia)
Additional mentors: Hervet Colinet (University of Rennes, France), Jean-Paul Léna (University of Lyon, France),
Additional collaborator: Shinichi Nakagawa (University of Alberta, Canada), Rob Salguero-Gómez (University of Oxford, United Kingdom)
1. General background
Biodiversity is currently facing an unprecedented crisis driven by global environmental change. In ectothermic organisms, climate change, and more specifically rising temperatures, has been identified as a major driver of population declines over recent decades – for instance in amphibians and reptiles. While the effects of temperature on ectotherm physiology, development, and performance are well documented, the demographic consequences of these individual-level processes remain poorly understood.
This lack of integration between thermal ecology and demography limits our ability to predict population persistence and to design effective conservation strategies under future climate scenarios. In this context, understanding how temperature variation influences vital rates – such as survival, reproduction, and growth – and how these changes scale up to affect population dynamics is a critical challenge in contemporary evolutionary ecology and conservation biology.
This PhD project aims to address these knowledge gaps by combining large-scale comparative data with advanced demographic and phylogenetic modelling frameworks to quantify the effects of temperature on population persistence and resilience across ectothermic taxa.
2. Aim 1 – Thermoregulation mode and adult survival responses to temperature variation in tetrapods
The first component of the thesis will assess how thermoregulation mode (endothermy versus ectothermy) shapes adult survival patterns and modulates survival responses to temperature variation at both intra- and interspecific levels. This objective will be addressed using large comparative survival datasets. For ectotherms, adult survival estimates will be drawn from ongoing work on amphibians and reptiles, encompassing more than 550 species and over 1,500 natural populations. For birds, published survival databases will be used (e.g. Schöler et al. 2019; Beauchamp et al. 2021). For mammals, the project will assemble the first comprehensive database of adult survival estimates spanning all major mammalian clades. Analyses will rely on Bayesian hierarchical phylogenetic meta-analyses implemented in the R package MCMCglmm (Hadfield 2010), allowing robust quantification of how thermoregulatory strategy mediates temperature–survival relationships across tetrapods.
3. Aim 2 – Temperature effects on vital rates and life-history strategies in ectotherms
The second component of the thesis will investigate how temperature variation affects survival, fecundity, and growth, and how changes in these vital rates translate into variation in population growth rate (λ) and life-history strategies. This aim will focus on ectothermic taxa, including both invertebrates and vertebrates (amphibians, reptiles, and fishes). For invertebrates, the project will rely primarily on published experimental studies. For vertebrates, raw demographic data from the ECTOLIFE database will be used for amphibians and reptiles, complemented by published demographic data for fishes. Methodologically, this component will integrate Bayesian phylogenetic imputation of missing vital rates, matrix population models, life-table response experiments (LTREs), and Bayesian phylogenetic path analyses. This combined framework will allow identification of the vital rates most sensitive to temperature variation and their relative contribution to population growth across ectothermic life-history strategies.
4. Aim 3 – Temperature effects on demographic resilience of ectotherm populations
The third component of the thesis will examine how temperature variation influences demographic resilience, defined as a population’s capacity to resist and recover from perturbations. Specifically, the project will quantify temperature effects on key resilience components: attenuation (the ability to buffer population declines following disturbance), amplification (the capacity for post-disturbance population increase), and recovery time (the time required to return to a stable demographic state). These questions will be addressed across ectothermic taxa, including both invertebrates and vertebrates (amphibians, reptiles, and fishes), using the demographic data and estimates generated in the previous components of the thesis. The analytical framework will combine phylogenetically informed Bayesian models with transient demographic analyses to estimate resilience metrics and assess their sensitivity to temperature variation.
5. Candidate profile
The ideal candidate will demonstrate:
• Strong quantitative skills and excellent command of R for data analysis and modelling.
• A clear interest in evolutionary ecology, demography, and large-scale comparative approaches.
• Willingness to engage with advanced statistical methods, including Bayesian models, phylogenetic comparative analyses, and matrix population models.
• Ability to manage and analyse large and complex datasets.
• Autonomy, scientific rigour, organisation, and strong critical thinking skills.
• Excellent written and oral communication skills in English.
• Ability to work within international research networks and collaborate across multiple institutions.
• High motivation, scientific curiosity, and the ambition to develop an international research profile in quantitative evolutionary ecology.
6. Eligibility and application
Administrative eligibility:
Applicants must hold a Master’s degree (or equivalent) in ecology, evolutionary biology, biostatistics, or a related discipline at the time the PhD begins.
Application details:
• Application deadline: 15/05/2026
• Interviews: 17/05/2026
• EGAAL interview: 06/2026
• Expected start date: 01/10/2026
To apply, please submit:
• A curriculum vitae (CV),
• A cover letter describing your motivation, relevant experience, and research interests,
• Contact details for three academic referees.
Applications and inquiries should be sent to: hugo.cayuela@univ-rennes.fr
7. Literature cited
Beauchamp, G. (2021). Flocking in birds increases annual adult survival in a global analysis. Oecologia, 197, 387-394.
Hadfield, J. D. (2010). MCMC methods for multi-response generalized linear mixed models: the MCMCglmm R package. Journal of Statistical Software, 33, 1-22.
Scholer, M. N., Strimas‐Mackey, M., & Jankowski, J. E. (2020). A meta‐analysis of global avian survival across species and latitude. Ecology Letters, 23, 1537-1549.
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