Reduced genetic variance among high fitness individuals: inferring stabilizing selection on male sexual displays in Drosophila serrata.

Directional selection is prevalent in nature, yet phenotypes tend to remain relatively constant, suggesting a limit to trait evolution. However, the genetic basis of this limit is unresolved. Given widespread pleiotropy, opposing selection on a trait may arise from the effects of the underlying alleles on other traits under selection, generating net stabilizing selection on trait genetic variance. These pleiotropic costs of trait exaggeration may arise through any number of other traits, making them hard to detect in phenotypic analyses. Stabilizing selection can be inferred, however, if genetic variance is greater among low- compared to high-fitness individuals. We extend a recently suggested approach to provide a direct test of a difference in genetic variance for a suite of cuticular hydrocarbons (CHCs) in Drosophila serrata. Despite strong directional sexual selection on these traits, genetic variance differed between high- and low-fitness individuals and was greater among the low-fitness males for seven of eight CHCs, significantly more than expected by chance. Univariate tests of a difference in genetic variance were nonsignificant but likely have low power. Our results suggest that further CHC exaggeration in D. serrata in response to sexual selection is limited by pleiotropic costs mediated through other traits.

Sztepanacz JL ，Rundle HD 《-》

Condition dependence of a multicomponent sexual display trait in Drosophila serrata.

Delcourt M ，Rundle HD 《-》

An evolutionary limit to male mating success.

McGuigan K ，Van Homrigh A ，Blows MW 《EVOLUTION》

Orientation of the genetic variance-covariance matrix and the fitness surface for multiple male sexually selected traits.

Blows MW ，Chenoweth SF ，Hine E 《-》

Comparing complex fitness surfaces: among-population variation in mutual sexual selection in Drosophila serrata.

Rundle HD ，Chenoweth SF ，Blows MW 《-》