The origin of species has been a central question in evolutionary biology ever since Darwin. Despite our great advances in knowledge about natural selection and adaptation within a species, there still remains much controversy over the meaning of species, the mechanisms by which new species originate, and the genetic basis of the traits responsible for defining a new species. The investigators propose to study these issues with male calling song in the Hawaiian cricket genus Laupala. There are currently 37 recognized species in this genus. The species tend to look alike, but they differ greatly in the time interval between sounds in the male calling song. It has been proposed that male song is used by females to identify potential mates. If true, male song would be important in defining the species boundaries of these crickets. They will test this hypothesis by using molecular genetic survey techniques to define populations of crickets that share similar genes. They will then see if genetically similar populations also share a common song. With the same molecular data they will also reconstruct an evolutionary tree of all the species. This evolutionary tree will allow them to estimate how the songs have evolved between species. These molecular data will also be used to test the hypothesis that the rate of DNA evolution is accelerated when a new species arises on a different island than its ancestor, as has been found for Hawaiian fruit flies (Drosophila). These data will also be used to test the hypothesis that differences in song among local populations within a species promote genetic differentiation. Finally, because they can successfully cross species in the laboratory, they will study the genetic basis of the song differences between species using traditional breeding analysis as well as modern molecular techniques to map and identify genes. This last study will not only allow them to address the evolutionary question of the types of genetic differences that arise among a species, but it will also a direct comparison of the traditional versus molecular approaches to genetic analysis: a comparison that is relevant to many applications in the health sciences.
