Geographic Variation in the Mitochondrial Control Region of Black-throated Blue Warblers (Dendroica caerulescens)

Abstract

ABSTRACT.— We investigated the genetic population structure of the Black-throated Blue Warbler (Dendroica caerulescens), a Nearctic-Neotropic migrant passerine that breeds in cool mixed deciduous-coniferous forests in eastern North America. A cline in plumage color in breeding populations in the central Appalachian Mountains suggests either a contact zone between two formerly allopatric populations or the presence of a strong contemporary selection gradient. Analysis of 333 base pairs of the mitochondrial control region from 287 individuals sampled from 14 populations revealed relatively high haplotype diversity, low nucleotide diversity, and limited but significant phylogeographic structure across the breeding range (analysis of molecular variance [AMOVA], variation among populations = 2.7%; P < 0.01) and between northern and southern population groups (AMOVA, variation among groups = 2.9%; P < 0.01). Genetic differentiation among populations did not conform to an isolation-by-distance model. Nucleotide ...