Sexually discordant selection is associated with trait specific morphological changes and a complex genomic response

Abstract

AbstractSexes often have differing fitness optima, potentially generating intra-locus sexual conflict, as each sex bears a genetic ‘load’ of alleles beneficial to the other sex. One strategy to evaluate conflict in the genome is to artificially select populations discordantly, against established sexual dimorphism, reintroducing attenuated conflict. We investigate a long-term artificial selection experiment reversing sexual size dimorphism inDrosophila melanogasterduring ∼350 generations of sexually discordant selection. We explore morphological and genomic changes to identify loci under selection between the sexes in discordantly and concordantly size selected treatments. Despite substantial changes to overall size, concordant selection maintained ancestral sexual dimorphism. However, discordant selection altered size dimorphism in a trait-specific manner. We observe multiple, possible soft selective sweeps in the genome, with size related genes showing signs of selection. Patterns of genomic differentiation between the sexes within lineages identified potential sites maintained by sexual conflict. One discordant selection lineage shows a pattern of elevated genomic differentiation on chromosome 3L, consistent with the maintenance of sexual conflict. Our results suggest measurable signs of conflict and differentially segregating alleles between the sexes due to discordant selection.