MITOCHONDRIAL-DNA VARIATION AND THE PHYLOGENY OF ZONOTRICHIA

We used 19 restriction endonucleases to analyze patterns of cleavage site variation in the mitrochondrial DNA (mtDNA) of the five recognized species of Zonotrichia. Each species possesses a unique mtDNA profile. Relative to most congeneric avian comparisons, these species are closely related, with an average percent nucleotide divergence of 4.1%. The Golden-crowned Sparrow (Z. atricapilla) and White-crowned Sparrow (Z. leucophrys) differ by a single restriction site (out of 122), which yields an estimate of 0.11% sequence divergence. These species are sister species in all phylogenetic analyses (Wagner and Dollo parsimony, bootstrapping, distance analyses), and White-throated Sparrow (Z. albicollis) is the sister to these, followed by Harris' Sparrow (Z. querula) and Rufous-collared Sparrow (Z. capensis). The phylogeny based on mtDNA restriction sites differs from that based on allozymes (Zink 1982) in that Harris' and White-throated sparrows are reversed in this sequence. In general, however, the allozyme and mtDNA phylogenies are highly concordant. Similarities in song between White-throated and Golden-crowned sparrow can be interpreted as ancestral retentions. The song of the White-crowned Sparrow is derived relative to other north temperate congeners, and song dialects appear to have evolved independently in White-crowned and Rufous-collared sparrows. Based on the mtDNA data, patterns of hybridization are inconsistent with phylogenetic relationships, and we suggest that hybridization should not be used in taxonomic decisions.