Supervisor: vanemteadur Urmas Saarma,
Opponent: prof. Ettore Randi, Bologna Ülikool
Phylogeography is a discipline that focuses on the principles and processes affecting the spatial distribution of genetic lineages, within and among closely related species. Among wild mammals, the brown bear (Ursus arctos) has become a model species for phylogeographic analysis, due to wide distribution, the availability of numerous subfossils and its female philopatry. Current thesis examined brown bear matrilineal phylogeography (by analysing mitochondrial DNA (mtDNA) sequences) in northern Eurasia with particular focus on the population in north-west Eurasia. Prior to the studies performed in the frame of this thesis, information on brown bear phylogeography was largely lacking for northern Eurasia, which nonetheless constitutes a major part of the species' current distribution and contains the majority of the world's brown bear population. The results suggest that all contemporary brown bears in northern Eurasia are relatively closely related and after the Last Glacial Maximum, brown bears underwent a sudden demographic expansion and no significant geographic barrier was found to restrict migration across northern continental Eurasia. Detailed analysis of the north-west Eurasian brown bear population using complete mitochondrial sequences revealed five divergent, geographically confined and only partially overlapping haplogroups. Our analysis demonstrated that these five haplogroups formed during the post-glacial period and thus reflect a combination of postglacial migration patterns and more recent demographic history. Ninety-five complete mitogenomes, sequenced during this study, allowed us to make the first analysis of intra-specific variation among brown bear mitogenomes. Positive selection was found to act on the gene ND6. The results of this study provide scientific data that is potentially very useful for the development of effective management and conservation strategies for Eurasian brown bears in the near future.