Pleistocene glacial cycles and physical barriers influence phylogeographic structure in black-capped chickadees, a widespread North American passerine

The non-migratory black-capped chickadee (Poecile atricapillus, Linnaeus 1766) has a continent-wide distribution extending across large parts of North America. To investigate the phylogeographic structure, and verify possible refugia during the last glacial maximum, we sequenced a 678 base pair region of the mitochondrial control region from 633 chickadees at 35 sites across North America, and performed paleoecological distribution modeling. Two genetically distinct groups were found using multiple analyses: one in Newfoundland and a widespread continental group, with additional substructure evident in western continental populations. While gene flow is low throughout the range, it is especially low in peripheral populations. The Newfoundland population has remained isolated from continental populations for at least 65,000 years and contains a number of fixed nucleotide differences. Within the continental populations, chickadees are subdivided into Pacific Coast, Alaska, southeast Rockies and main-northeast groups consistent with late Pleistocene vicariance events. Evidence of secondary contact was identified between the Pacific and main-northeast populations in northwest British Columbia and between the southeast Rockies and main-northeast group in Montana. Paleoecological distribution modeling predicted suitable habitat in Alaska, off the coast of Newfoundland and several locations across the southern United States during the last glacial maximum; whereas suitable habitat during the last interglacial was more similar to the contemporary distribution.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author