Sequence evolution of the Gpdh gene in the Drosophila virilis species group.

The nucleotide sequence of the Gpdh gene from six taxa, D. virilis, D. lummei, D. novamexicana, D. a. americana, D. a. texana and D. ezoana, belonging to the virilis species group was determined to examine details of evolutionary change in the structure of the Gpdh gene. The Gpdh gene is comprised of one 5' non-translated region, eight exons, seven introns and three 3' non-translated regions. Exon/intron organization was identical in all the species examined, but different from that of mammals. Interspecific nucleotide divergence in the entire Gpdh gene followed the common pattern: it was low in the exon, high in the intron and intermediate in the non-translated regions. The degree of nucleotide divergence differed within these regions, suggesting that selection exerts constraints differentially on nucleotide change of the Gpdh gene. A phylogenetic tree of the virilis phylad constructed from nucleotide variation of total sequence was consistent with those obtained from other data.