EvoLunch Seminar: Sylvain Glémin (CNRS Rennes, FR)

How and why genetic diversity varies among species is a long-standing question in evolutionary biology. Life history traits have been shown to explain a large part of observed diversity. Among them, mating systems have one of the strongest impacts on genetic diversity, with selfing species usually showing much lower diversity than outcrossing relatives. Theory predicts that a high rate of selfing amplifies selection at linked sites, reducing genetic diversity genome-wide, but frequent bottlenecks and rapid population turn-over could also explain low genetic diversity in selfers. How linked selection varies with mating systems and whether it is sufficient to explain the observed difference between selfers and outcrossers is thus still unclear. I will present a comparative population genomic study in Aegilops/Triticum grass species, a group characterized by contrasted mating systems (from obligate outcrossing to high selfing) and marked recombination rate variation across the genome, to quantify the effects of mating system and linked selection on patterns of neutral and selected polymorphism. I will also present ongoing methodological developments to better estimate the joined effect of demography and linked selection on polymorphism patterns, in particular in partially selfing species.