Data from: When east meets west: population structure of a high- latitude resident species, the boreal chickadee (Poecile hudsonicus)

MtDNA data showed evidence of eastern and western groups, with secondary admixture occurring in central Canada. This suggests that the boreal chickadee probably persisted in multiple glacial refugia, one in Beringia and at least one in the east. Palaeo-distribution modelling identified suitable habitat in Beringia (Alaska), Atlantic Canada and the southern United States, and correspond to divergence dates of 60–96 kya.

Pairwise FST values for both mtDNA and microsatellites were significant for all comparisons involving Newfoundland, though mtDNA data suggest a more recent separation. Furthermore, unlike mtDNA data, nuclear data support population connectivity among the continental populations, possibly due to male-biased dispersal. Although both are significant, the isolation-by-distance signal is much stronger for mtDNA (r2=0.51) than for microsatellites (r2=0.05), supporting the hypothesis of male-biased dispersal.

The population structure of the boreal chickadee was influenced by isolation in multiple refugia and contemporary barriers. In addition to geographical distance, physical barriers such as the Strait of Belle Isle and northern mountains in Alaska are restricting gene flow, whereas the Rocky Mountains in the west are a porous barrier.

Usage notes

Microsatellite raw data of 6 loci for boreal chickadees across North America The file contains the raw sizes for six microsatellite loci. Regions were isolated using M13-labelled target-site specific primers and run on a 6% gel using a LI-COR 4300 DNA Analyzer. Sizes were scored by hand relative to 4 standards and a mystery plate.

Samples were either collected in the field or were provided by museums (see SI). HDY-12-OR0281-microsatellite raw data.xlsx