Limited gene flow among brown bear populations in far Northern Europe? Genetic analysis of the east–west border population in the Pasvik Valley

Noninvasively collected genetic data can be used to analyse large-scale connectivity patterns among populations of large predators without disturbing them, which may contribute to unravel the species’ roles in natural ecosystems and their requirements for long-term survival. The demographic history of brown bears (Ursus arctos) in Northern Europe indicates several extinction and recolonization events, but little is known about present gene flow between populations of the east and west. We used 12 validated microsatellite markers to analyse 1580 hair and faecal samples collected during six consecutive years (2005‐2010) in the Pasvik Valley at 70� N on the border of Norway, Finland and Russia. Our results showed an overall high correlation between the annual estimates of population size (Nc), density (D), effective size (Ne) and Ne ⁄Nc ratio. Furthermore, we observed a genetic heterogeneity of 0.8 and high Ne ⁄Nc ratios of 0.6, which suggests gene flow from the east. Thus, we expanded the population genetic