Sex chromosomes and the evolution of sexual dimorphism.

Abstract

An analytical model was used to explore the effect of X-linkage on the evolution of sexual dimorphism. The model examined the requisite conditions for increase when rare, and the equilibrium frequency of genes that produce a 'sexually-antagonistic' phenotype, ie a phenotype that is selectively favored in one sex but disfavored in the other sex. A simulation model was used to examine the evolution of sex-limited modifier genes that restrict the expression of sexually-antagonistic genes in the sex where they are selected against. Sex chromosomes appear to facilitate the evolution of sexual dimorphism and X-linked genes have a predominant role in coding for sexually dimorphic traits.-from Author