Meeting Abstract
Genitalia are some of the most rapidly evolving structures in the animal kingdom, and sexual selection is thought to be the primary driver of genital diversity. One promising approach to the study of genital evolution is to explore whether and how selection acts on standing intraspecific variation. This includes female structures, which are traditionally underrepresented in the literature, as well as male structures. Using Drosophila melanogaster as a model system, I explore how variation in a male genital structure, the posterior lobe, and a recently discovered female structure, the oviscapt pouch, affect copulatory behavior. Morphometric analyses of isogenic lines suggest that genetic variation in structure size and shape is present in natural populations. Field-sampling efforts further confirm a substantial amount of phenotypic variation is present in most wild populations. Using variants of a gene enhancer region that controls both posterior lobe and oviscapt pouch development, I generated fly lines with measurable differences in lobe and pouch dimensions. This fine-scale manipulation of male and female traits has minimal additional pleiotropic consequences. I found sex-dependent effects of morphological changes on trait function during courtship and copulation. These data represent a fundamental link between specific gene enhancers and genital structure function, and are especially novel in their application to female genitalia. This connection illuminates the interplay between small molecular changes and whole-organism performance.
