Characterizing Dietary Effects on Drosophila melanogaster Reproductive Behaviors

Abstract

When choosing a mate, animals evaluate the attractiveness of potential partners. Attractiveness and its perception are condition-dependent traits. Animal condition is affected by complex interactions between genetic and environmental factors. Although the effects of diet on the condition of Drosophila melanogaster is well known, dietary effects on mating behavior are not well characterized. D. melanogaster, a genetic model organism, has been underutilized in the examination of intraspecific mate discrimination. In my Ph.D. dissertation, I developed behavioral assays to examine how macronutrient enriched diets affect D. melanogaster reproductive behaviors, demonstrating how traditional genetic models can advance condition-dependent mate choice studies.

I first examined how flies raised on either a control or a fat, protein, or sugar enriched diet interacted during courtship. Each diet affected the flies differently, and the responses were sexually dimorphic. High sugar diet had negligible effects. High protein diet affected only copulatory and post-copulatory traits, while high fat diet affected all traits with a stronger effect on females. I next examined the post-copulatory effects caused by low to high protein diets. This study confirmed that dietary protein content affects reproductive traits in a sexually dimorphic manner, as male contributed reproductive costs to females decrease with increasing protein content, while female contributions to the cost increase with dietary protein levels. Finally, I examined what female sexual cues could be altered by high fat diet (HFD), and the genetic factors that mediate HFD behavioral responses. I found that HFD alters female pheromone profiles to alter precopulatory behavior. Genetic manipulation of the same conserved metabolic pathways that rescue HFD health defects only rescued HFD male mating defects, further illustrating the sexual dimorphism of conditional responses in D. melanogaster. Through these three dissertation chapters, I have established a robust method for examining both environmental and genetic effects on a complex behavioral system.