Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands ( ABC islands) of Alaska. Here, we present...

Collared lemmings (genus D icrostonyx ) are circumpolar A rctic arvicoline rodents associated with tundra. However, during the last glacial maximum ( LGM ), D icrostonyx lived along the southern ice margin of the L aurentide ice sheet in communities comprising both temperate and boreal species. To better understand these communities and the fate of these southern individuals, we compare mitochondrial cytochrome b sequence data...