Wednesday, June 26, 2013

Sakha origins


Sakha origins

An interesting quote from the paper:

Although the genetic heritage of the native populations of Sakha is mostly of East Asian ancestry, analyses of autosomal SNP data as well as haploid loci also show a minor West Eurasian genetic component. The patchy presence of the “European” (blue) component in the ADMIXTURE plot (Figure 6), most pronounced in Yukaghirs, probably testifies to recent admixture with Europeans. In addition, the presence of European-specific paternal lineages R1a-M458, I1 and I2a among Yakuts, Dolgans, Evenks and Yukaghirs likely points to a recent gene flow from East Europeans. Although only individuals with self-reported unadmixed ancestry for at least two generations were included in the study of haploid loci, mistakes in ethnic self-identification cannot be entirely excluded. One of the main sources of gene flow has likely been Russians who accounted for 37.8% of the population of Sakha in 2010 [61]. The migration of Russians (at first mainly men) to eastern Siberia started already in the 17th century, when Yakutia was incorporated into the Russian Empire [62]. But:
The mtDNA haplogroup J detected in the remains from a Yakut burial site dated to the beginning of the 17th century [41], long before the beginning of the settlement of Russian families in the 18th century [63], clearly points to more ancient gene flow from western Eurasia. The presence of haplogroups H8, H20 and HV1a1a among the Yakuts, Dolgans and Evenks (Figure 1) also suggests gene flow other than from Russians, because these haplogroups are rare (H8 and H20) or even absent (HV1a1a) among Russians [64-67], but are common among southern Siberian populations as well as in the Caucasus, the Middle and Near East [19,68-70].Moreover, the HVSI haplotypes of H8, H20a and HV1a1a in our sample exactly match those in the Buryats from the Buryat Republic [19]. Similarly, the Ychromosome haplogroup J in Dolgans and Evens very likely testifies to gene flow through South Siberia, as it is present among native South Siberian populations [47,71]. The scenario of ancient gene flow from West Eurasia is supported by ancient DNA data, which show that in the Bronze and Iron Ages, South Siberia, including the Altai region, was an area of overwhelmingly predominant western Eurasian settlement [72,73], and the Indo-European migration even reached northeastern Mongolia [74]. To summarize, the West Eurasian genetic component in Sakha may originate from recent admixture with East Europeans, whereas more ancient gene flow from West Eurasia through Central Asia and South Siberia is also probable. 
BMC Evolutionary Biology 2013, 13:127 doi:10.1186/1471-2148-13-127 
Autosomal and uniparental portraits of the native populations of Sakha (Yakutia): implications for the peopling of Northeast Eurasia 
Sardana A Fedorova et al. 
Abstract (provisional)
Background
Sakha -- an area connecting South and Northeast Siberia -- is significant for understanding the history of peopling of Northeast Eurasia and the Americas. Previous studies have shown a genetic contiguity between Siberia and East Asia and the key role of South Siberia in the colonization of Siberia. 
Results
We report the results of a high-resolution phylogenetic analysis of 701 mtDNAs and 318 Y chromosomes from five native populations of Sakha (Yakuts, Evenks, Evens, Yukaghirs and Dolgans) and of the analysis of more than 500,000 autosomal SNPs of 758 individuals from 55 populations, including 40 previously unpublished samples from Siberia. Phylogenetically terminal clades of East Asian mtDNA haplogroups C and D and Y-chromosome haplogroups N1c, N1b and C3, constituting the core of the gene pool of the native populations from Sakha, connect Sakha and South Siberia. Analysis of autosomal SNP data confirms the genetic continuity between Sakha and South Siberia. Maternal lineages D5a2a2, C4a1c, C4a2, C5b1b and the Yakut-specific STR sub-clade of Y-chromosome haplogroup N1c can be linked to a migration of Yakut ancestors, while the paternal lineage C3c was most likely carried to Sakha by the expansion of the Tungusic people. MtDNA haplogroups Z1a1b and Z1a3, present in Yukaghirs, Evens and Dolgans, show traces of different and probably more ancient migration(s). Analysis of both haploid loci and autosomal SNP data revealed only minor genetic components shared between Sakha and the extreme Northeast Siberia. Although the major part of West Eurasian maternal and paternal lineages in Sakha could originate from recent admixture with East Europeans, mtDNA haplogroups H8, H20a and HV1a1a, as well as Y-chromosome haplogroup J, more probably reflect an ancient gene flow from West Eurasia through Central Asia and South Siberia. 
Conclusions
Our high-resolution phylogenetic dissection of mtDNA and Y-chromosome haplogroups as well as analysis of autosomal SNP data suggests that Sakha was colonized by repeated expansions from South Siberia with minor gene flow from the Lower Amur/Southern Okhotsk region and/or Kamchatka. The minor West Eurasian component in Sakha attests to both recent and ongoing admixture with East Europeans and an ancient gene flow from West Eurasia.