The cradle of Russians, an obvious Finno-Volgaic genetic hotspot

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First look of an accepted manuscript (behind paywall), Genome-wide sequence analyses of ethnic populations across Russia, by Zhernakova et al. Genomics (2019).

Interesting excerpts:

There remain ongoing discussions about the origins of the ethnic Russian population. The ancestors of ethnic Russians were among the Slavic tribes that separated from the early Indo-European Group, which included ancestors of modern Slavic, Germanic and Baltic speakers, who appeared in the northeastern part of Europe ca. 1,500 years ago. Slavs were found in the central part of Eastern Europe, where they came in direct contact with (and likely assimilation of) the populations speaking Uralic (Volga-Finnish and Baltic- Finnish), and also Baltic languages [11–13]. In the following centuries, Slavs interacted with the Iranian-Persian, Turkic and Scandinavian peoples, all of which in succession may have contributed to the current pattern of genome diversity across the different parts of Russia. At the end of the Middle Ages and in the early modern period, there occurred a division of the East Slavic unity into Russians, Ukrainians and Belarusians. It was the Russians who drove the colonization movement to the East, although other Slavic, Turkic and Finnish peoples took part in this movement, as the eastward migrations brought them to the Ural Mountains and further into Siberia, the Far East, and Alaska. During that interval, the Russians encountered the Finns, Ugrians, and Samoyeds speakers in the Urals, but also the Turkic, Mongolian and Tungus speakers of Siberia. Finally, in the great expanse between the Altai Mountains on the border with Mongolia, and the Bering Strait, they encountered paleo-Asiatic groups that may be genetically closest to the ancestors of the Native Americans. Today’s complex patchwork of human diversity in Russia has continued to be augmented by modern migrations from the Caucasus, and from Central Asia, as modern economic migrations take shape.

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Sample relatedness based on genotype data. Eurasia: Principal Component plot of 574 modern Russian genomes. Colors reflect geographical regions of collection; shapes reflect the sample source. Red circles show the location of Genome Russia samples.

In the current study, we annotated whole genome sequences of individuals currently living on the territory of Russia and identifying themselves as ethnic Russian or as members of a named ethnic minority (Fig. 1). We analyzed genetic variation in three modern populations of Russia (ethnic Russians from Pskov and Novgorod regions and ethnic Yakut from the Sakha Republic), and compared them to the recently released genome sequences collected from 52 indigenous Russian populations. The incidence of function-altering mutations was explored by identifying known variants and novel variants and their allele frequencies relative to variation in adjacent European, East Asian and South Asian populations. Genomic variation was further used to estimate genetic distance and relationships, historic gene flow and barriers to gene flow, the extent of population admixture, historic population contractions, and linkage disequilibrium patterns. Lastly, we present demographic models estimating historic founder events within Russia, and a preliminary HapMap of ethnic Russians from the European part of Russia and Yakuts from eastern Siberia.

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Sample relatedness based on genotype data. Western Russia and neighboring countries: Principal Component plot of 574 modern Russian genomes. Colors reflect geographical regions of collection; shapes reflect the sample source. Red circles show the location of Genome Russia samples.

The collection of identified SNPs was used to inspect quantitative distinctions among 264 individuals from across Eurasia (Fig. 1) using Principal Component Analysis (PCA) (Fig. 2). The first and the second eigenvectors of the PCA plot are associated with longitude and latitude, respectively, of the sample locations and accurately separate Eurasian populations according to geographic origin. East European samples cluster near Pskov and Novgorod samples, which fall between northern Russians, Finno-Ugric peoples (Karelian, Finns, Veps etc.), and other Northeastern European peoples (Swedes, Central Russians, Estonian, Latvians, Lithuanians, and Ukrainians) (Fig. 2b). Yakut individuals map into the Siberian sample cluster as expected (Fig. 2a). To obtain an extended view of population relationships, we performed a maximum likelihood-based estimation of ancestry and population structure using ADMIXTURE [46](Fig. 2c). The Novgorod and Pskov populations show similar profiles with their Northeastern European ancestors while the Yakut ethnic group showed mixed ancestry similar to the Buryat and Mongolian groups.

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Population structure across samples in 178 populations from five major geographic regions (k=5). Samples are pooled across three different studies that covered the territory of Russian Federation (Mallick et al. 2016 [36], Pagani et al. 2016 [37], this study). The optimal k-value was selected by value of cross validation error. Russian samples from all studies (highlighted in bold dark blue) show a slight gradient from Eastern European (Ukrainian, Belorussian, Polish) to North European (Estonian Karelian, Finnish) structures, reflecting population history of northward expansion. Yakut samples from different studies (highlighted in bold red) also show a slight gradient from Mongolian to Siberian people (Evens), as expected from their original admixture and northward expansions. The samples originated from this study are highlighted, and plotted in separated boxes below.

Possible admixture sources of the Genome Russia populations were addressed more formally by calculating F3 statistics, which is an allele frequency-based measure, allowing to test if a target population can be modeled as a mixture of two source populations [48]. Results showed that Yakut individuals are best modeled as an admixture of Evens or Evenks with various European populations (Supplemental Table S4). Pskov and Novgorod showed admixture of European with Siberian or Finno-Ugric populations, with Lithuanian and Latvian populations being the dominant European sources for Pskov samples.

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The heatmaps of gene flow barriers show for each point at the geographical map the interpolated differences in allele frequencies (AF) between the estimated AF at the point with AFs in the vicinity of this point. The direction of the maximal difference in allele frequencies is coded by colors and arrows.

So, Russians expanding in the Middle Ages as acculturaded Finno-Volgaic peoples.

Or maybe the true Germano-Slavonic™-speaking area was in north-eastern Europe, until the recent arrival of Finno-Permians with the totally believable Nganasan-Saami horde, whereas Yamna -> Bell Beaker represented Vasconic-Caucasian expanding all over Europe in the Bronze Age. Because steppe ancestry in Fennoscandia and Modern Basques in Iberia.

A really hard choice between equally plausible models.

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