Dynamics of sexual selection in diploid populations

Describes results for a diploid, 2-locus model for the evolution of a female mating preference directed at an attractive male trait subject to viability and/or fertility selection. Using computer simulation, the authors studied a large, random sample of parameter values, assuming additivity of alleles at the preference locus and partial dominance at the trait locus. Results were classifiable into 9 types of parameter sets, each differing in equilibria, evolutionary trajectories, and rates of evolution. For many parameters, evolutionary trajectories converged on curves within the allelic frequency plane and subsequently evolved along the curves toward fixation. Neutrally stable curves of equilibria did not occur in Fisherian models that assume only viability and sexual selection unless there is complete dominance at the trait locus. The Fisherian models also exhibited oscillation of allelic frequencies and unique polymorphic equilibria. "Sexy son' models in which attractive males had reduced fertility were much less likely to lead to increase in traits and preferences than were the Fisherian models. However, if less fertile males had increased viability, trait polymorphisms and fixation of rare "sexy' alleles occurred. -from Authors