Phylogenetic analysis of brown bear (Ursus arctos) populations across Türkiye

Brown bears (Ursus arctos) are omnivores distributed across Eurasia and North America. Previous studies based on mitochondrial DNA (mtDNA) revealed significant differences in genetic variation between European and Middle Eastern brown bears, with each region characterized by distinct haplogroups. Türkiye, as a crossroads between three continents, is an important region for brown bear diversity, as it harbors haplotypes from both regions. However, previous information on brown bear genetic diversity in Türkiye was based on only mtDNA sequences and limited sample sizes. Therefore, the role Türkiye has played in the evolutionary history of brown bears is still largely unknown. Here, using genome-wide sequencing data together with the mtDNA D-loop region sequences, we aim to fill this gap by investigating the patterns of brown bear genetic diversity and differentiation across Türkiye and nearby regions. Our results demonstrate the geographical distribution of haplogroups across Türkiye and show that Turkish populations have three distinct mtDNA haplogroups clustered into western and eastern geographic groups. Genome-wide SNP analysis supported this conclusion, with high patterns of genetic diversity and distinct geographic structuring. Collectively, our results indicate that the evolutionary dynamics influencing brown bear populations across Türkiye and the Middle East are distinct and Türkiye's brown bears have higher genetic diversity than other world populations.