Effects of Genetic Dominance on Runaway Sexual Selection

Distinguishing among theories of sexual selection requires that one develop diagnostic predictions that can be tested in living systems. Recently, genetic studies of female species preferences in Drosophila supported the predictions of a model of sexual selection through pleiotropy with adap tive traits: preferences generally behaved as recessive characters. However, the dominance predic tions of female preferences resulting from runaway sexual selection have not been investigated. Here, I present an extension of previous simulation models of runaway sexual selection by varying the dominance of the female preference and incorporating genetic drift. I show that runaway sex ual selection is generally more likely to favor the evolution of dominant female preferences than recessive ones. Also, in contrast to the results of a previous study, dominant preferred male char acters spread more quickly by runaway sexual selection than recessive ones under some conditions. Overall, the predictions derived from this model of runaway sexual selection are not supported by empirical data on the genetic basis of species preferences, suggesting that runaway sexual selection may not be a major force in the evolution of such preferences. More empirical studies will be nec essary to further evaluate both the predictions and the assumptions of this model, however.