Meeting Abstract
Differences in mating behaviors are a common mechanism preventing mating between species. However, little is known about how mating behaviors become different between species, at the genetic or neurological level. In Drosophila, pheromones act as important species-specific signals that prevent hybridization. In D. sechellia, females express the pheromone 7,11-heptacosadiene (7,11-HD); D. simulans females express a different pheromone. D. sechellia males are stimulated to court by 7,11-HD. But for D. simulans, 7,11-HD suppresses courtship behavior. Because these species overlap in range, male pheromone preference is the primary mechanism preventing hybridization, accounting for ~71% of the gene flow restricted between them. We have harnessed this difference in pheromone preference, in combination with next generation DNA sequencing technology, to identify the genetic basis of male pheromone response. We have mapped a majority of the difference (~61%) in pheromone preference to a small region on a single chromosome, suggesting that sexual isolation may be attributed to a small genomic region with large effect. This locus also controls other aspects of male courtship behavior, like latency and investment. This implies that substantial mating barriers can evolve via changes to just a couple genes, rapidly isolating populations. We will present the results of our efforts to fine-map this region and test a widely-studied gene of interest, expressed in the developing fly brain, for its role in behavioral divergence. We aim to provide an in-depth study of the mechanisms underlying the evolution of a reproductively isolating behavior—a necessary goal of behavioral research, so that we may uncover general patterns in the changes underlying evolutionary shifts in behaviors that isolate species.
