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Flux génique et sélection fréquence-dépendante négative au locus d'auto-incompatibilité chez les plantes

SJ

Membre a labase

Simon Joly

Résumé du colloque

The development of approaches to identify loci under selection is a major goal of population genomics. For loci under negative frequency dependent selection, one potentially diagnostic signature is higher effective migration rates compared with neutral loci. Using a novel procedure to estimate divergence time and migration rate simultaneously for two sets of loci, we examined sequence variation at loci linked and unlinked to the self-incompatibility locus (S-locus) in Leavenworthia alabamica and L. crassa (Brassicaceae). Contrary to expectation, significantly higher migration rates could not be detected at the S-linked locus. Forward simulations clarify that this pattern may be expected when species are recently diverged, as is the case for these Leavenworthia species. The simulations demonstrate that the effective migration rate at the S-locus increases with time following speciation, beginning with values equal to those of neutral loci, but eventually stabilizing at much higher values. We argue that increased divergence at the S-locus generates stronger selection favoring novel immigrant alleles. Taking divergence time into account may be an important requirement of population genomics efforts that seek to detect selection and perhaps can best be achieved by modifying inference-based approaches to allow migration rates to change over time.

Contexte

manager icon Responsables :
Hervé Philippe
host icon Hôte : Université de Montréal

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