Genetic patterning in Central Eurasia: population history and pigmentation

Central-western Asia has often been underrepresented in population genetic studies, but it is important for the clarification of the peopling of Eurasia and the relationship between its western and eastern extremities. We genotyped individuals from over 40 population groups, mostly central Eurasian, for mitochondrial HVR1, CCR5del32 and five functional MC1R variants (p.Val60Leu, p.Val92Met, p.Arg151Cys, p.Arg160Trp, p.Arg163Gln), and collected published genotype data for comparison. Mitochondrial profiles confirm both the higher heterozygosity in Central Asia than in surrounding areas, and the broadly northern European distribution of CCR5del32. The MC1R variants profile alone is a good determinant of the longitudinal position of a population group, and combined FST values divide Eurasia into seven broad geographic divisions. We can conclude that Central Asia shares genetic features with both eastern and western Eurasia, compatible with both a scenario where the former acted as a source for the latter two’s genetic diversity, or one where Central Asia is a ‘hybrid zone’ where eastern and western peoples met. Furthermore, the overall high FST values for functional MC1R variants combined with presumed selection pressures on skin pigmentation in low-UV areas lead us to conclude that different variants were selected for in east and west Eurasia, an example of convergent evolution.