Fig. 5.—

Sex antagonism and evolution of gene expression level (made after Barrett and Hough 2013): A hypothetical scenario in which females (red) and males (blue) have different optima for the same trait, causing sex-biased selection (blue and red arrows). A shared genetic architecture can constrain the sexes from evolving toward their respective trait optima (grey arrows). However, sexual dimorphism can still evolve when such trade-offs exist, and this can involve sex-limited gene expression and the breakdown of strong intersexual genetic correlations, possibly facilitated by the evolution of SNRs.