GENOMICS OF SPECIATION IN DROSOPHILA ATHABASCA
Understanding the process of speciation is one of the primary aims in the field of evolutionary biology. As in all fields, techniques and models for studying species divergence have changed over time to take advantage of current technology. However, despite recent advances in molecular genetics and genomics, very little is actually known about the genome-wide patterns important to the evolution of species. The widespread availability of whole genome sequencing techniques opens up the opportunity to examine this topic at the genomic level. In fact, a very recent study utilized comparative genomics to identify differences between the genomes of species within the Drosophila pseudoobscura subgroup . However, although a comparative species approach is helpful for examining species differences, to study the process of speciation, a population genomic approach is necessary.
The Drosophila athabasca species complex, which is composed of three overlapping populations – Western-Northern, Eastern-A, and Eastern-B – provides a unique system in which to study incipient speciation using population genomics. The three populations of D. athabasca are estimated to have diverged between 5,000-23,000 years ago and are morphologically indistinguishable . Individuals will hybridize in the laboratory, but geographical ranges, fixed inversions, and distinct courtship songs resulting in premating isolation differentiate the populations sufficiently for them to be designated as separate semispecies . Recent divergence is ideal because speciation studies that rely only on examining differences between biologically distinct species may not detect forces important to the early stages of speciation and instead may be identifying differences that have secondarily accumulated. To identify features and patterns in the genome important for creating and maintaining new species, it is essential that we examine how evolution acts to maintain genetic boundaries of recently diverged populations, such as those in D. athabasca. This proposal takes advantage of both the unique semispecies complex of D. athabasca and whole genome sequencing techniques to uncover genome-wide evolutionary patterns that are important for population divergence and incipient speciation, allowing me to characterize the genes responsible for the creation of new species.