Molecular Phylogeny of the Large Carpenter Bees, Genus Xylocopa (Hymenoptera: Apidae), Based on Mitochondrial DNA Sequences

Abstract

Carpenter bees, genus Xylocopa Latreille, a group of bees found on all continents, are of particular interest to behavioral ecologists because of their utility for studies of the evolution of mating strategies and sociality. This paper presents phylogenetic analyses based on sequences of two mitochondrial genes cytochrome oxidase 1 and cytochrome b for 22 subgenera of Xylocopa. Maximum-parsimony and maximum-likelihood methods were used to infer phylogenetic relationships. The analyses resulted in three resolved clades of subgenera: a South American group (including the subgenera Stenoxylocopa, Megaxylocopa, and Neoxylocopa), a group including the subgenera Xylocopa s.s. and Ctenoxylocopa, and an Ethiopean group (including the subgenera Afroxylocopa, Mesotrichia, Alloxylocopa, Platynopoda, Hoploxylocopa, and Koptortosoma). The relationships between the 11 other subgenera and the resolved clades are unclear. Within the Ethiopian group we found a clear separation of the African and the Oriental taxa and apparent polyphyly of the subgenus Koptortosoma. Using an evolutionary rate for ants, we investigated whether Gondwana vicariance or more recent dispersal events could best explain the present-day distribution of subgenera. Although some taxa show divergences that approach Gondwanan breakup times, most divergences between geographic groups are too recent to support a vicariance hypothesis.