Evidence for mitochondrial DNA recombination in a human population of island Melanesia

Mitochondrial DNA (mtDNA) analysis has proved useful in studies of recent h uman evolution and the genetic affinities of human groups of different geog raphical regions. As part of an extensive survey of mtDNA diversity in pres ent-day Pacific populations, we obtained sequence information of the hyperv ariable mtDNA control region of 452 individuals from various localities in the western Pacific. The mtDNA types fell into three major groups which ref lect the settlement history of the area. Interestingly, we detected an extr emely rare point mutation at high frequency in the small island of Nguna in the Melanesian archipelago of Vanuatu. Phylogenetic analysis of the mtDNA data indicated that the mutation was present in individuals of separate mtD NA lineages. We propose that the multiple occurrence of a rare mutation eve nt in one isolated locality is highly improbable, and that recombination be tween different mtDNA types is a more likely explanation for our observatio n. If correct, this conclusion has important implications for the use of mt DNA in phylogenetic and evolutionary studies.