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Dernière mise à jour : Mai 2018

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ESE - Ecology and Ecosystem Health

Comparative population genomics in animals and plants: genetic diversity, selection efficacy and effective population size

ESEminar 2019-05-14
Sylvain Glémin, UMR ECOBIO, CNRS Rennes, will lead the next ESEminaire

When? Tuesday 14 May 2019, at 13:00

Where? Roux Amphitheatre, Building 15, Agrocampus Ouest

Abstract

What determines levels of genetic diversity within species is a central question in evolutionary biology but has remained a puzzling question for decades. Particularly the relative influences of species biology and ecology versus population history have been much debated. To address this question we investigated the genome-wide diversity of 76 non-model animal species by sequencing the transcriptome of two to ten individuals  in each species. The distribution of synonymous genetic diversity (πS)  between species revealed no detectable influence of geographic range or  invasive status but was accurately predicted by key species traits related to parental investment: long-lived or low-fecundity species with  brooding ability were genetically less diverse than short-lived or highly fecund ones. Then we extended this analysis to a comparison with plants by analysing full-genome data in 34 animal and 28 plant species.
As in animals, we found a strong effect of longevity and, in addition, of mating systems. We then tested whether the efficacy of purifying selection was affected by the effective size of a population (Ne). In agreement with the nearly neutral theory of molecular evolution, we found a strong negative correlation between πS (as a proxy for Ne) and πNS, the ratio of non-synonymous vs synonymous diversity (as a proxy for the efficacy of purifying selection). In addition, we also found that the distribution of fitness effect of mutations also varies among species, contributing to variation in πNS
Finally I will present results on the specific effect of mating systems  on genetic diversity and the efficacy of selection at a much smaller phylogenetic scale, focusing on wheat relatives. From these results, I will discuss how global life-history strategies can affect Ne and the efficacy of selection and whether genomic-based measures, such as πNS, can tell us something about the fate of a species.