Fine-scale genetic analysis of species-specific female preference in Drosophila simulans

Behavioral differences are thought to be the first components to contribute to species isolation, yet the precise genetic basis of behavioral isolation remains poorly understood. Here, we used a combination of behavior assays and genetic mapping to provide the first refined map locating candidate genes for interspecific female preference isolating Drosophila simulans from D. melanogaster. First, we tested whether two genes identified as affecting D. melanogaster female intraspecific mate choice also affect interspecific mate choice; neither of these genes was found to contribute to species-specific female preference. Next, we used deficiency mapping to locate genes on the right arm of the third chromosome for species-specific female preference and identified five small significant regions that contain candidate genes contributing to behavioral isolation. All five regions were located in areas that would have low interspecific recombination, which mirrors the results of other behavioral isolation studies that used quantitative trait locus (QTL) mapping, but without the potential concern of bias towards regions of low recombination that QTL mapping may have. Since this model system may be refined to the individual gene level using the same methodology, this initial map we provide may potentially serve as a ready template for the identification and characterization of the first behavioral isolation genes.