The Hawaiian Islands with their populations of endemic Drosophila species provide an ideal natural laboratory for studying evolution and ecological adaptations. The vitellogenin or yolk protein genes of these diverse Hawaiian flies comprise an exceptional model system for analyzing mechanisms and rates of gene evolution in higher organisms. The members of this gene cluster, encoding three vitellogenin proteins, are subject to strict developmental regulation, which controls timing, tissue- specificity and rates of vitellogenin synthesis to coordinate egg maturation of each species with its particular ecological habitat. The proposed research will use the most recently developed techniques of molecular biology to expedite determination of DNA sequences of these genes in nine species and assay levels of sequence variation within and between populations of two species. DNA sequence comparisons will identify the molecular basis of interspecific differences in vitellogenin gene structure and function. Gene changes between species will be related to adaptive shifts in host plants and reproductive strategies, the goal being to distinguish the roles played by various types of DNA sequences in species evolution. Comparisons of phylogenies constructed using divergence in coding versus control sequences will test the hypothesis that regulatory changes in the genome are more closely aligned with adaptive and phylogenetic change.
