Patterns of Allozyme, Mitochondrial DNA, and Morphometric Variation in Four Sparrow Genera

Abstract

We sequenced 432 base pairs (bp) of the mitochondrial DNA (mtDNA) cytochrome-b gene in all recognized biological species in the genera Zonotrichia, Passerella, and Melospiza, as well as Junco hyemalis and Pipilo chlorurus. Our goals were: to estimate the phylogenetic pattern within and among genera; to compare our estimate with previous estimates based on allozymes and mtDNA restriction sites; to map morphometric distances onto the phylogenetic hypothesis; and to determine the extent of geographic variation in two polytypic species, the Fox Sparrow (Passerella iliaca) and Song Sparrow (Melospiza melodia). There was no geographic pattern to cytochrome-b variation within the Song Sparrow, whereas four mtDNA lineages of Fox Sparrows were found; these results corroborate those obtained from mtDNA restriction-site data. Analysis of cytochrome b yielded 14 equally-parsimonious trees. Although mtDNA and allozyme trees were statistically congruent, they differed somewhat, and the data were combined to estimate phylogeny; two equally-parsimonious trees resulted. The consensus tree indicated the following relationships: within Melospiza, the pattern is {Song Sparrow {Swamp Sparrow [M. georgiana], Lincoln's Sparrow [M. lincolnii]}}; Junco and Zonotrichia are sister genera; within Zonotrichia, the pattern is {Rufous-collared Sparrow [Z. capensis] {White-throated Sparrow [Z. albicollis] {Harris' Sparrow [Z. querula] {White-crowned Sparrow [Z. leucophrys], Golden-crowned Sparrow [Z. atricapilla]}}}}; the data could not reliably resolve relationships among the other genra. In general, restriction sites and cytochrome-b sequence data yielded congruent phylogenies. Morphometric distances mapped onto the phylogenetic hypothesis revealed instances in which molecular and phenotypic evolution proceeded at different rates, except within Melospiza, where the two data sets yielded congruent patterns. Song dialects apparently evolved twice within Zonotrichia.