MITOCHONDRIAL-DNA VARIATION AND EVOLUTIONARY RELATIONSHIPS IN THE AMAKIHI COMPLEX

An analysis of restriction-site variation in mitochondrial DNA was conducted to examine relationships among five taxa in one group of honeycreepers-the amakihi complex (genus Hemignathus). We analyzed 35 ingroup and 3 outgroup samples. Tree topologies, based on both distance and parsimony methods, grouped taxa into two distinct lineages: the virens-wilsoni lineage; and the chloris-stejnegeri-parvus group. Inter-island sequence divergence (average d(xy) = 0.0368) is considerably higher than intra-island variation (mean d(x) = 0.0035), and is higher than average for avian species. Variability (measured as both nucleotide diversity and maximum divergence between haplotypes) differs among island populations. Molecular evolutionary rates were calibrated on the basis of maximum island age estimates; sequence divergence in this lineage is approximately 2% per million years. The relationships within the chloris-stejnegeri-parvus clade generally are consistent with the previously proposed model of double invasion. Genetic distances and the pattern of relationships among amakihi taxa indicate that species status for H. v. chloris and H. v. stejnegeri may be warranted.