Molecular phylogeny of tephritid fruit flies in the Bactrocera tau complex using the mitochondrial COI sequences.

We compared sequences of the mitochondrial cytochrome oxidase I gene of eight species of the Bactrocera tau complex using Bactrocera dorsalis, Bactrocera pyrifoliae, Ceratitis capitata, Anopheles gambiae, and Locusta migratoria as outgroups. A 639-bp variable region was sequenced. The sequence divergence between species in the B. tau complex ranged from 0.06 to 28%, and up to 29% between the complex and its tephritid outgroups, B. dorsalis and C. capitata. According to the phylogenetic relationships, these members of the B. tau complex could be classified into four clades. Thus, species A and D form clades 1 and 3, respectively, while species C and I belong to clade 4. However, species B, E, and F form a distinct group, clade 2, and infested the fruits of non-cucurbit hosts. Host-plant shifts resulting in adaptive radiation and premating isolation among species might play an important role in species differentiation of the B. tau complex.