Phylogeography of Mitochondrial DNA in Two Species of White-Eyes in Australia

Abstract

Variation was assessed among mitochondrial DNAs (mtDNAs) from geographically dispersed individuals of two species of white-eyes (Zosterops lutea and Z. lateralis) in Australia. The survey revealed high levels of intraspecific divergence. The mtDNA of Z. lutea was paraphyletic; eastern samples were more closely related to eastern Z. lateralis than to western Z. lutea. The mtDNA of Z. lateralis showed a major phylogenetic break within the distribution of one subspecies, Z. l. halmaturina, and was relatively uniform across four subspecies distributed along the east coast of Australia. The discordance between species boundaries and the distribution of mtDNA haplotypes is probably due to historical hybridization. The poor correspondence between subspecies boundaries and mtDNA discontinuities in Z. lateralis implies that patterns of morphological variation may reflect local processes more than evolutionary history. In a sample of the morphologically divergent island race, Z. l. chlorocephala, mtDNA haplotypes were identical to those found on the adjacent mainland. However, the frequencies of mtDNA variants differed considerably between the two places. These data suggest that the island race is recently derived from the mainland, but that current gene flow is rare.