Mitochondrial DNA analysis of Iranian brown bears (Ursus arctos) reveals new phylogeographic lineage

Brown bears are mostly found in relatively low densities in the mountainous forests of Iran, from north to northwest and west, as well. Phylogeographic and genetic relationships between Iranian brown bears and others in the world are still unclear. We sequenced a 614 bp fragment of mtDNA control region of 15 sampled brown bears throughout Iran, where a dataset comprising a total number of 336 sequences belonging to brown and polar bears was included in the analyses. As compared to other brown bears, the Iranian brown bear presents remarkable haplotype diversity (15 individuals, 12 new haplotypes). Phylogenetic analyses revealed one major previously uncharacterized mtDNA lineage within Iranian brown bears, comprising 2–3 subclades: (i) Northern Iran, which includes bears from the Alborz and the Iranian Caucasus Mountains; (ii) Western Iran, including the individuals from the Zagros Mountains; and (iii) Fars, which comprises bears living in the Southern Zagros Mountains. These subclades are found in different geographic locations in Iran, indicating pronounced current population structuring in females. Moreover, statistical analyses of fixation index (FST) and analysis of molecular variance (AMOVA) demonstrate significant genetic structure among the subclades. Fu's FS test suggested that northern and western Iranian brown bears probably underwent a recent population expansion, indicating significant deviations from neutrality. Overall, these findings likely imply the survival of brown bears in several refugia during the last glacial maximum in (or near) Iran.