Basal relationships in the Drosophila melanogaster species group.

The Drosophila melanogaster species group is a popular model for evolutionary studies due to its morphological and ecological diversity and its inclusion of the model species D. melanogaster. However, phylogenetic relationships among major lineages within this species group remain controversial. In this report, the phylogeny of 10 species representing each of the well-supported monophyletic clades in the melanogaster group was studied using the sequences of 14 loci that together comprise 9493 nucleotide positions. Combined Bayesian analysis using gene-specific substitution models produced a 100% credible set of two trees. In the strict consensus of these trees, the ananassae subgroup branches first in the melanogaster species group, followed by the montium subgroup. The remaining lineages form a monophyletic clade in which D. ficusphila and D. elegans branch first, followed by D. biarmipes, D. eugracilis, and the melanogaster subgroup. This strongly supported phylogeny resolves most basal relationships in the melanogaster species group, and provides a framework that can be extended in the future to encompass more species.