Phylogeographic analysis of mitochondrial genome polymorphism in the Shors

The variability of nucleotide sequences of complete mitochondrial genomes in the Shors, a Turkic-speaking people from the Altai-Sayan region, was studied. The Shors exhibit a high level of nucleotide diversity due to the presence of two components of the East and West Eurasian origin in their gene pool (79.5 and 20.5 %, respectively). However, a relatively low level of mtDNA haplotype diversity was found among the Shors, which is associated with the high prevalence of certain identical mitochondrial haplotypes. Multidimensional scaling of interpopulation genetic distances indicates that the Shors fall in between East Asian ethnic groups and indigenous East Siberian peoples. By examining the polymorphism of whole mitochondrial genomes in individuals with the same hypervariable segment 1 haplotype belonging to haplogroup F1b1, found in ~37 % of the Shors, we identified six mtDNA haplotypes belonging to haplogroups F1b1-b1 and F1b1-b2. Phylogeographic analysis shows that the Shor mitochondrial gene pool is characterized by a high frequency (65.9 %) of mtDNA haplogroups found solely in the Altai-Sayan region: A-a1c1a, B4b1a3a1a, C4a1a4a1a, C4e, C5c*, D4b1a2a1a, D4m2a2, D5c1a2b, F1b1-b1, F1b1-b2, F2b1b1, and H8b1a. According to molecular dating results, the evolutionary age of these mtDNA haplogroups varies from 0.9 to 5.0 thousand years. All of the mtDNA haplogroups listed are of East Asian origin, except for the West Eurasian H8b1a. The isolated evolution of mitochondrial haplogroups specific to the peoples of the Altai-Sayan region is assumed to have been facilitated by their isolation from East Asian neighbors. This isolation occurred during the Bronze Age, when the Afanasyevo culture formed as a result of the mixing of indigenous populations and migrants - representatives of the Yamnaya culture, which existed in the Urals and Volga regions. In the absence of a significant influx of additional East Asian mtDNA haplotypes to the populations of the Altai-Sayan region over several thousand years, it appears that existing genetic lineages of East Asian origin diversified.