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

• Published in: Ecology and Evolution
• Main Authors: Campagna, Leonardo, Van Coeverden de Groot, Peter J., Saunders, Brenda L., Atkinson, Stephen N., Weber, Diana S., Dyck, Markus G., Boag, Peter T., Lougheed, Stephen C.
• Other Authors: Government of Nunavut, Government of the Northwestern Territories, Nunavut Wildlife Management Board, Indian and Northern Affairs, University of Saskatchewan, NSERC
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2013
• Subjects: Arctic; Canadian Arctic Archipelago; M'Clintock; M'Clintock Channel; Northwest Passage; The Gib; Arctic Archipelago; Global warming; Northwest passage; Sea ice; Ursus maritimus
• Online Access: http://dx.doi.org/10.1002/ece3.662; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fece3.662; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.662

Abstract As global warming accelerates the melting of A rctic sea ice, polar bears ( U rsus 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 C anadian A rctic A rchipelago spanning the G ulf of B oothia ( 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 ( F ST = 0.01) and mitochondrial (Φ ST = 0.47; F ST = 0.29) loci, allowing B ayesian clustering analyses to assign individuals to either group. Our data imply that the causes of the mitochondrial and nuclear genetic patterns differ. Analysis of mt DNA reveals the matrilineal structure dates at least to the Holocene, and is common to individuals throughout the species’ range. These mt DNA 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 mt DNA capture different aspects of a species demographic history.