Proposal for a thesis project in comparative ecophysiology – application to the Ecole Doctorale 227 competitive process at Sorbonne University

Laboratory iEES Paris, Paris
Supervisors: Jean-François Le Galliard & Tom van Dooren (CNRS)

We are looking for a candidate to apply for a thesis subject for the ED 227 competitive selection process with the alternative possibility of a fully funded contract from the IBEES program at Sorbonne University.

Subject
Arid environments are characterized by a combination of high temperature and low precipitation with a scarcity of water resources in time and space. Semi-arid to arid regions represent about 30 to 40% of the planet’s continental surface. It is expected that their surface will increase considerably with global warming. While climatic constraints result in low species diversity, they also act as a powerful evolutionary filter selecting specialized taxa to resist and survive in water restricted environments. Studying the evolution of species traits along aridity gradients is therefore crucial to understand these adaptive processes, identify constraints and assess which functional traits or species are most sensitive to global changes.

To this end, this thesis project proposes to analyze the evolution of a set of functional traits strongly involved in adaptation to arid climates in squamate reptiles. Squamates are a monophyletic order of scaly vertebrates (Lepidosauria) comprising about 11,000 species of lizards, snakes and amphisbenians. They occupy all continental environments with peaks of diversity in the tropics, Oceania and southern Africa6. Their resistance to aridity involves functional traits controlling water loss (morphology and behaviors), energy metabolism, and thermoregulation (thermal preferences and behaviors). No study has specifically characterized the coevolutionary sequence of these traits along aridity gradients.

The project will build on the expertise of the iEES Paris laboratory in collaboration with ISYEB, CEBC and the University of Antwerp to understand the variability of thermohydroregulatory strategies using large ecophysiological, bioclimatic and biogeographic datasets, modern phylogenetic comparative analyses and focused empirical studies. Specifically, we will exploit a global database characterizing squamate water loss to determine environmental correlates of interspecific variability in water resistance. We will cross-reference these data with thermoregulatory and metabolic data to characterize the evolution of thermohydroregulatory syndromes along aridity gradients. We will complement these global analyses with a targeted study of the evolution of skin water loss in Lacertidae by collecting new data on approximately 40 species representative of a diversity of environments9. Finally, focusing on historical climate niche modeling and evolutionary sequence analysis, we will specifically look for key innovations and life history tactics that allow these species to maintain or colonize arid habitats. These comparative analyses will take into account phylogenetic proximity of species as well as differences in activity patterns, diet and morphology.

Profile sought:
The desired candidate will meet the following requirements: (1) have a strong background in functional and evolutionary ecology including skills in biostatistics and animal ecophysiology, (2) be creative and independent, and (3) have experience in the professional field (comparative analyses, ecophysiology, phylogeny). He or she will have the freedom to propose complementary work that will allow the adaptation of the thesis project.

Details on the ED 227 website:
https://www.adum.fr/as/ed/voirproposition.pl?langue=&site=ed227&matricule_prop=40294

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