Sex-limited mutations and the evolution of sexual dimorphism

Although the developmental and genetic mechanisms underlying sex difference s are being elucidated in great detail in a number of species, there remain s a breach between proximate and evolutionary studies of sexual dimorphism. More precisely, the evolution of sex-limited gene expression at autosomal loci has not been well reasoned using either theoretical or empirical metho ds. Here, I show that a Mendelian genetic model including elementary detail s of sexual differentiation provides novel insight into the evolution of se x differences via sex limitation. This model indicates that the nature of a llelic effects and the pattern of selection must be known in both sexes to predict the evolution of sex differences. That is, selection interacts with genetic variation for sexual dimorphism to produce unanticipated patterns of trait divergence or convergence between the sexes. Ultimately, this mode l may explain why previous models for the evolution of sexual dimorphism do not predict the erratic behavior of the sex difference during artificial s election experiments.