Stefano MONA

Diplôme :
HDR
Date :
mercredi 02 mai 2018 - 14:00

M. Stefano MONA présente ses travaux en soutenance en vue de l'obtention de l'Habilitation à diriger des recherches

  • Muséum National d'Histoire Naturelle, Amphithéâtre d'Anatomie Comparée et de Paléontologie, 2 rue Buffon, 75005 Paris
  • Jury : M. GUILLAUME ACHAZ, Mme SOPHIE ARNAUD-HAOND, M. FRÉDÉRIC AUSTERLITZ, M. LOUNES CHIKHI, Mme CLAUDIE DOUMS, Mme STÉPHANIE MANEL

Over the last years, a long debate originated between supporters of phylogeography and theirs opponents. A model-based approach is now generally recommended, despite its inherent limits. The most obvious is related to the choice of the model: the battery of potential demographic models is infinite, so how can we find the one that best fit to our data? A wrong model will always give an answer, a wrong one. But quoting George Box, “all models are wrong, but some are useful”. My research focuses in finding models that are “less wrong” than others and exploiting their usefulness despite their limits. This is clearly a very general question in population genetics. I therefore restricted my attention to a more specific example: population structure, how much should we worry when performing demographic inferences? The goal of this thesis is not to give an answer to this question, but rather to raise attention to this important point which is unfortunately overlooked in the literature. Most of the species are indeed structured in meta-populations, i.e., organized in a network of demes exchanging migrants to some extent. Failing to take population structure into account can severely bias our understanding of the demography of a species, going from false signatures of population bottleneck and more generally false changes in effective population time through time. Here I will show how to interpret genetic diversity and how to reconstruct the evolutionary history of a species using meta-population models, trying also to show their relationship with unstructured models and how to combine them to obtain a clearer picture of the history of the species under investigation. I will present some simulation results as well as empirical applications to real data, particularly focusing on the evolutionary history of the black tip reef shark Carcharhinus melanopterus.