Opportunities and Constraints Imposed by the G matrix of Drosophila buzzatii Wings

Abstract

The Drosophila wing is a structure shared by males and females with the primary function of flight. However, in males, wings are also used to produce songs or visual displays during courtship. Understanding the genetic architecture underlying wing variation within and between the sexes is central to predicting the possible outcomes of evolutionary pressures. Here, we investigate these issues by studying how the wing has evolved in twelve populations of Drosophila buzzatii, a species for which the courtship song is crucial to copulation. We found that females and males evolved in slightly different directions and that cross-sex covariances reduced the predicted response to selection in the direction of the extant sexual dimorphism. Moreover, we found evidence of directional selection consistent with the hypothesis of asymmetric selection acting on wing shape in each sex. In summary, the evolution of D. buzzatii wing shape seems to be the product of a complex interplay between genetic constraints due to between-sex pleiotropy, and conflicting selective pressures.