The primary objective of this project is to investigate both interspecific and intraspecific variation in the Drosophila willistoni group, through analysis of structural and DNA sequence polymorphism in the Alcohol dehydrogenase (Adh) gene. Specific aims of this study are 1) to analyze structural polymorphism at the Adh locus of the willistoni group by assaying for the presence/absence of the third intron of the Adh gene 2) determine the degree of DNA sequence polymorphism in the Adh gene among species of the willistoni group and within D. willistoni 3) to derive a phylogeny of the willistoni group and the subgenus Sophophora using DNA sequence data and 4) to analyze the degree of inter- and intraspecific codon usage bias for Adh in the willistoni group. The codon usage analysis will aim at determining 1) if the level of codon usage bias varies among species of the willistoni group and/or within D. willistoni 2 if rate of synonymous substitution is constrained by codon usage bias and 3) if there is a preference for a particular base at the third position of codons. This study uses molecular population genetics and evolutionary genetics of the Adh locus to examine evolutionary patterns in the D. willistoni group, and will further our understanding of evolution at the molecular level.
