Genic capture, sex linkage, and the heritability of fitness.

Several sexual selection models predict that females will obtain indirect genetic benefits by preferentially mating with males that transmit high-quality genes to their offspring. However, despite widespread observations of additive population genetic variation for fitness as well as for male sexually selected traits, estimated fitness associations between fathers and offspring are often weak. Perhaps more puzzling, the strength of these associations differs drastically between species, leading many researchers to question the relevance of genetic benefits for processes of sexual selection. Here, I show that a species' sex chromosome system can strongly influence the genetic architecture of male and female fitness variation and, consequently, the heritability of fitness between fathers and their offspring. Indirect genetic benefits are reduced, and sexually antagonistic costs are pronounced, in species with X chromosomes relative to species with homomorphic sex chromosomes, environmental sex determination, or Z chromosomes. Data from the sexual selection literature are consistent with predictions of the models, though additional studies will be required to circumvent phylogenetic nonindependence between sex determination systems. This study strongly suggests that inferences about genetic benefits of female choice must be considered within a species-specific genomic context, and it has several implications for the evolution of female preferences as well as the genomic consequences of sex and sexual selection.