Figure 1: Sexually antagonistic selection and monogamy.
From: Evolution under monogamy feminizes gene expression in Drosophila melanogaster
Levels of gene expression may experience no sexually antagonistic selection if male and female expression levels evolved to reach sex-specific optima (dashed lines) (a). Alternatively, sexually dimorphic genes may experience sexually antagonistic selection (indicated by arrows) if expression in each sex is genetically constrained (symbolized by a bracket) (b). Under monogamy, sexual selection on males may be either weakened (c) or shift the position of male optima (d), both of which favour feminization of male-biased genes (indicated by the shift in distributions). The same prediction of feminization under monogamy holds for female-biased genes.
