Systematics and Evolution of the Drosophila buzzatii (Diptera: Drosophilidae) Cluster Using mtDNA

The Drosophila buzzatii Patterson & Wheeler cluster (repleta group) includes seven species: D. buzzatii Patterson & Wheeler, D. koepferae Fontdevila et al. D. serido Vilela & Sene, D. seriema Tidon-Sklorz & Sene, D. borborema Vilela & Sene, D. sp. D and D. sp. B. These flies are widely distributed in South America outside the Amazon region. The systematics of this cluster has been based on chromosomal inversions and the aedeagus is used to identify species. These species use necrotic cactus tissues as breeding sites. The current hypothesis of differentiation and speciation of these species is related to expansion and retraction of cactus distribution in South America during Quaternary climatic cycles. We investigated the phylogenetic relationship among species of this cluster based on the mtDNA COI gene region and compared it with the relationship established using classical markers. The resulting phylogenetic hypothesis indicated that this cluster is a monophyletic group that can be divided into two sets of species: the one including D. buzzatii and D. koepferae and other with the remaining five species. The latter can also be divided into two clades. Although this branching pattern is similar to the one established by classical markers, some disagreement involving populations was observed that suggests secondary contact between populations of different species. The distribution pattern of COI haplotypes is partitioned geographically, which could be the result of limited gene flow between groups of species suggesting a longer history of differentiation than previously hypothesized for D. buzzatii cluster species.