ENS

PSL

Département de Biologie École normale supérieure Directeur : Pierre Paoletti

12h

Le séminaire de Charles MULLON (University of Lausanne) aura lieu dans la salle Favard, IBENS 46 rue d’Ulm 75005 Paris

Abstract : Selection often favours different trait values in males and females, leading to genetic conflicts between the sexes when traits share a genetic basis. Such sexual antagonism has been proposed as a mechanism to maintain genetic polymorphism. However, this notion relies largely on population genetic models of single loci with fixed fitness effects. In this talk, I’ll review recent findings that challenge this view. Specifically, we modelled the evolution of a continuous trait with a shared genetic basis but differing optima in males and females, examining various genetic architectures and fitness landscapes. For autosomal loci, the long-term maintenance of polymorphism requires strong sexual conflict generating unusual sex-specific fitness patterns. More realistic fitness landscapes typically produce stabilising selection, resulting in an evolutionarily stable state dominated by a single homozygous genotype. Thus, genetic variation from sexual antagonism at autosomal loci is likely rare and transient, making it difficult to detect. In contrast, loci tightly linked to the sex-determining region are more conducive to sexually antagonistic variation, generating strong selection to reduce recombination and facilitating the linkage of sexually antagonistic alleles to the sex where they confer advantages. This process can initiate and accelerate sex chromosome evolution.