Data from: Extensive sampling of polar bears (Ursus maritimus) in the Northwest Passage (Canadian Arctic Archipelago) reveals population differentiation across multiple spatial and temporal scales

As global warming accelerates the melting of Arctic sea ice, polar bears
(Ursus maritimus) must adapt to a rapidly changing landscape. This process
will necessarily alter the species distribution together with population
dynamics and structure. Detailed knowledge of these changes is crucial to
delineating conservation priorities. Here, we sampled 361 polar bears from
across the center of the Canadian Arctic Archipelago spanning the Gulf of
Boothia (GB) and M'Clintock Channel (MC). We use DNA microsatellites
and mitochondrial control region sequences to quantify genetic
differentiation, estimate gene flow, and infer population history. Two
populations, roughly coincident with GB and MC, are significantly
differentiated at both nuclear (FST = 0.01) and mitochondrial (ΦST = 0.47;
FST = 0.29) loci, allowing Bayesian clustering analyses to assign
individuals to either group. Our data imply that the causes of the
mitochondrial and nuclear genetic patterns differ. Analysis of mtDNA
reveals the matrilineal structure dates at least to the Holocene, and is
common to individuals throughout the species’ range. These mtDNA
differences probably reflect both genetic drift and historical
colonization dynamics. In contrast, the differentiation inferred from
microsatellites is only on the scale of hundreds of years, possibly
reflecting contemporary impediments to gene flow. Taken together, our data
suggest that gene flow is insufficient to homogenize the GB and MC
populations and support the designation of GB and MC as separate polar
bear conservation units. Our study also provide a striking example of how
nuclear DNA and mtDNA capture different aspects of a species demographic
history.