Abstract
Human adaptation to extreme climatic and geographic conditions mediated by natural selection may be one of the major factors for formation of genetic structure in North Eurasian populations. Using data on a genome-wide set of single nucleotide polymorphisms (SNPs), we searched for the signals of positive selection in five populations of Siberia and the Russian European North. From 113 to 185 genomic regions with extended homozygous haplotypes blocks containing altogether 771 genes were found in each of the populations. Cross-population search of the selection targets resulted in about 150 genomic regions, 57 of which overlap with the results of haplotype analysis in individual populations. Genomic loci with the most profound signals of positive selection in northern populations include regions of SLC30A9, CACNA1C, KCNQ5, ABCA1, ALDH1A2, CSMD1, RBFOX1, and WWOX, as well as some other genes. Bioinformatics analysis demonstrated that major biological processes where selection targets are implicated are those conferring the response to external stimuli, including proteins, nutrients, and glucose, and defense reactions, including inflammatory immune response. The network of protein-protein interactions of genes under positive selection forms distinct clusters related to a number of biological processes indicated above. Results of the study indicate that non-neutral microevolution mechanisms may play a substantial role in genetic structuring of the human populations during long-term adaptation to unfavorable environmental conditions.