Figure 1.

Sexually antagonistic selection on gene expression. (a) Sexual antagonism is resolved when sex-specific selection pressures (grey arrows for female specific, white for male specific) produce sex-biased gene expression. (b) For genes with broad overall fitness optima, sexual antagonism can produce clear male (white) and female (grey) distinctions as a result of sex-specific selection on any specific function. (c) For genes with pleiotropic effects, constraints from other functions, shown with black arrows prevent sex-specific selection from decoupling male and female expression levels, preventing the resolution of sexual antagonism. (d) These genes have narrow fitness optima, and therefore female and male profiles are largely overlapping.