The quantitative genetic basis of female and male body size and their implications on the evolution of body size dimorphism in the house cricket Acheta domesticus (Gryllidae)

Abstract

Few theoretical and experimental studies have analyzed the genetic basis of body size dimorphism. Since the evolutionary response to selection depends of the genetic variance in a population it is to be expected that traits under selection would have smaller genetic variance than traits not affected by selection. The evolution of sexual size dimorphism is affected by the genetic correlation between females and males, with the most dimorphic traits showing smaller genetic correlations between the sexes. As result of the differences in the intensity of sexual selection between the sexes, it is expected that the levels of genetic variance would be larger in females than males. I analyzed the genetic additive variance underlying six traits of Acheta domesticus, and the genetic correlations between females and males. The most dimorphic trait with the smallest genetic correlation between the sexes was forewing length, this trait showing genetic variance only in females. It may be that sexual selection acting on male traits has depleted the genetic variance not only in male traits but also for those female traits that have a large genetic correlation with male traits. It is also possible that the evolution of sexual dimorphism in A. domesticus could be constrained as a result of the large genetic correlation between the sexes. Copyright by the Brazilian Society of Genetics.