Rates and patterns of mitochondrial DNA sequence evolution in fringilline finches (fringilla spp.) and the greenfinch (Carduelis chloris)

Rates and patterns of evolution in partial sequences of five mitochondrialgenes (cytochrome b, ATPase 6, NADH dehydrogenase subunit 5, tRNA(Glu), andthe control region) were compared among taxa in the passerine bird generaFringilla and Carduelis. Rates of divergence do not vary significantlyamong genes, even in comparisons with the control region. Rate variationamong lineages is significant only for the control region and NADHdehydrogenase subunit 5, and patterns of variation are consistent with theexpectations of neutral theory. Base composition is biased in all genes butis stationary among lineages, and there is evidence for directionalmutation pressure only in the control region. Despite these similarities,patterns of substitution differ among genes, consistent with alternativeregimes of selective constraint. Rates of nonsynonymous substitution arehigher in NADH dehydrogenase subunit 5 than in other protein-coding genes,and transitions exist in elevated proportions relative to transversions.Transitions appear to accumulate linearly with time in tRNA(Glu), anddespite exhibiting the highest overall rate of divergence among species,there are no transversional changes in this gene. Finally, for resolvingphylogenetic relationships among Fringilla taxa, the combinedprotein-coding data are broadly similar to those of the control region interms of phylogenetic informativeness and statistical support.