Rapid evolution of ecological sexual dimorphism driven by resource competition

Abstract

Sex differences in ecologically-important traits are common in animals and plants, and prompted Darwin to first propose an ecological cause of sexual dimorphism. Despite theoretical plausibility and Darwins original notion, a role for ecological resource competition in the evolution of sexual dimorphism has never been directly demonstrated and remains controversial. I used experimental evolution in Drosophila melanogaster to test the hypothesis that resource competition can drive the evolution of sex differences in diet. Following just three generations of adaptation, offspring from flies evolved in low-resource, high-competition environments show elevated sexual dimorphism in diet preference compared to both the ancestor and populations evolved on high resource availability. These results provide the first real-time direct evidence for evolution of sexual dimorphism driven by an ecological cause. One sentence summarySex differences in fly diet evolved rapidly under elevated competition, demonstrating ecological cause of sex differences.