Admixture and gene flow from Russia in the recovering Northern European brown bear (Ursus arctos)

Large carnivores were persecuted to near extinction during the last centuries, but have now recovered in some countries. It has been proposed earlier that the recovery of the Northern European brown bear is supported by migration from Russia. We tested this hypothesis by obtaining for the first time continuous sampling of the whole Finnish bear population, which is located centrally between the Russian and Scandinavian bear populations. The Finnish population is assumed to experience high gene flow from Russian Karelia. If so, no or a low degree of genetic differentiation between Finnish and Russian bears could be expected. We have genotyped bears extensively from all over Finland using 12 validated microsatellite markers and compared their genetic composition to bears from Russian Karelia, Sweden, and Norway. Our fine masked investigation identified two overlapping genetic clusters structured by isolation-by-distance in Finland (pairwise FST = 0.025). One cluster included Russian bears, and migration analyses showed a high number of migrants from Russia into Finland, providing evidence of eastern gene flow as an important driver during recovery. In comparison, both clusters excluded bears from Sweden and Norway, and we found no migrants from Finland in either country, indicating that eastern gene flow was probably not important for the population recovery in Scandinavia. Our analyses on different spatial scales suggest

Riistantutkimuksen symposium Petroskoissa syyskuussa 2018

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Red squirrels decline in abundance in the boreal forests of Finland and NW Russia

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Evidence of post-glacial secondary contact and subsequent anthropogenic influence on the genetic composition of Fennoscandian moose (Alces alces)

AimTo determine whether a contemporary population of the moose (Alces alces), a large northern ungulate, retains genetic signatures of post-glacial recolonization and/or the effects of anthropogenic factors. We focused on investigating spatial genetic structure and the distribution of genetic diversity of this species to clarify its still obscure history. LocationEastern Fennoscandia, Northern Europe. MethodsIn total, 574 Finnish and Russian Karelian moose were genotyped at 16 microsatellite loci, and the mitochondrial control region was sequenced from 224 individuals. Spatially explicit Bayesian clustering, multivariate and spatial autocorrelation methods were applied alongside traditional F-statistics to study the effects of landscape on genetic structure. The demographic history of our study populations was explored with coalescent analysis and Bayesian skyline plots. ResultsA major mitochondrial divergence of moose was discovered between northern parts of Finland and the rest of the studied area. Landscape genetic analyses on the microsatellite data identified three genetic clusters connected by clines, with coalescent analysis indicating the division to be of ancient origin. Additionally, recent population bottlenecks were detected using Bayesian skyline plots. Main conclusionsOur results indicate a post-glacial secondary contact between two distinct moose mitochondrial lineages that diverged during the Pleistocene, whereas admixture of three diverged genetic subpopulations was detected using microsatellites. The emergence of these subpopulations was estimated to have occurred after the post-glacial recolonization of Fennoscandia. The observed genetic bottlenecks coincide with recorded historical population declines in the 18th century. We conclude that the contemporary genetic composition of the moose population in eastern Fennoscandia has been affected by both ancient and recent factors.201