Reproductive isolation is important for the maintenance of species as distinct entities. Since reproductive isolation is often predominantly maintained through behavioral traits, it can be affected by changes in courtship patterns. The period (per) gene of Drosophila, because it is species-specific and regulates an aspect of courtship song, provides an opportunity to examine change in a courtship behavior, as related not only to reproductive isolation but also amino acid and nucleotide level changes. An ideal group in which to study these relationships is Drosophila willistoni and its sibling or closely related species. The group exhibits different degrees of reproductive isolation among its species, semispecies and subspecies. Specifically the project will examine; 1) the molecular variation in per and behavioral variation in courtship song for several populations of D. willistoni; 2) the variation in the gene locus and in song for the D. willistoni sibling species; 3) if there is evidence for reproductive character displacement among populations of D. paulistorum living together vs those living isolated from each other and 4) relationships of the sibling species as determined by the per sequence. This project should help explain the relationships of genetic variation, behavioral change, and reproductive isolation in the formation of species.
