Artificial selection to increase the phenotypic variance in gmax fails

Stabilizing selection is important in evolutionary theories of the maintenance of genetic variance, and has been invoked as the key process determining macro-evolutionary patterns of trait evolution. However, manipulative evidence for the extent of stabilizing selection, particularly on multivariate trait combinations is lacking. We used artificial disruptive selection in Drosophila serrata as a tool to determine the relative strength of stabilizing selection experienced by multivariate trait combinations with contrasting levels of genetic and mutational variance. Contrary to expectation, when disruptive selection was applied to the major axis of standing genetic variance, we observed a significant and repeatable decrease in its phenotypic variance. In contrast, the trait combination predicted to be under strong stabilizing selection, showed a significant and repeatable increase in its phenotypic variance. Correlated responses were observed in all selection treatments, and
viability s...