Sexually antagonistic selection: a review of the theory and its implications

Ewan Flintham, Thomas Lesaffre, Sarah Otto, Charles Mullon 

Sexually antagonistic selection arises when females and males have different fitness optima for traits with a shared genetic basis, so that the same alleles are favoured in one sex but disfavoured in the other. It has been implicated in a wide range of ecological and evolutionary processes, from the maintenance of a sex load to the evolution of sex chromosomes. Mathematical models have long been central to understanding sexually antagonistic selection and its consequences. Here, we review the theory of sexual antagonism across population genetic, adaptive dynamics, and quantitative genetic models. We highlight how these approaches give concordant and complementary descriptions of evolution in response to sex-specific selection and consider extensions incorporating genetic drift, non-random mating, demographic effects, jointly evolving multiple traits, sex-specific inheritance, and the evolution of genetic modifiers. We then discuss how these results bear on the sex load, the maintenance of genetic polymorphism, the evolution of sex linkage and sex chromosomes, and the origins of sexual dimorphism. By making assumptions and mechanisms explicit across approaches, we identify which conclusions are robust and which depend on specific modelling choices and finally outline open questions for future theoretical work.