Nucleotide sequence comparison of the Adh gene in three drosophilids

Summary The alcohol dehydrogenase (Adh) gene has been isolated fromDrosophila simulans andD. mauritiana by screening clone libraries of each with a previously cloned Adh gene fromD. melanogaster. The isolated clones were subcloned and partially sequenced to determine the relatedness of these species and to examine details of evolutionary change in the structure of the Adh gene. We report the sequence of the first 704 nucleotides of each gene as well as 127 bases in the 5 untranslated region. When these sequences are compared,D. melanogaster differs fromD. simulans andD. mauritiana by 2.8% and 3.1%, respectively.D. simulans andD. mauritiana differ by only 1.8%, implying that they are more closely related to each other than either is toD. melanogaster. This is consistent with phylogenetic relationships established by a variety of genetic, biochemical, and morphological means and illustrates that DNA sequencing of a single gene may be used to assess the evolutionary relationships of species.