The period gene: High conservation of the region coding for Thr-Gly dipeptides in the Drosophila nasuta species subgroup

In this study, the region corresponding to the Thr-Gly region of the period (per) gene in the Drosophila nasuta subgroup of species was sequenced. The results showed, that this region was highly conserved in the D. nasuta sub group. There were only nine variable sites found in this 300-bp-long region , all located in two small regions highly variable among Drosophila species . No length variation was observed either within this subgroup or in the Yu nnan (YN) population of D. albomicans. The deduced amino acid sequences wer e identical for all 14 taxa in the D. nasuta subgroup, and a stretch of alt ernating Thr-Gly pairs was not observed in this subgroup. A phylogenetic tr ee was constructed. The clustering of some species was in general agreement with previous works, but it also raised some question on the phylogenetic relationship between the nasuta species. The data did not implicate the Thr -Gly region playing a role in behavioral isolation in this subgroup of Dros ophila.