This question have been following me since the last previous blogpost where I found this geographical distribution of chunkcounts PCA dimension 4 between Euroasian populations.
Everybody would probably agree about the northern distribution shown in blue and green apparently showing a genetic connection between North-East European populations like Saamis and Finns and Northern Siberian populations all the way from Fennoscandia to Beringia in Eastern Siberia as shown many times in this blog, from university research and from other bloggers. However if we look closer at the color distribution for the map:
We should of course not take this color distribution to literally as PCA plots distirbutions can be affected by many things but as we can see the red grade is close to the brown. This probably means the whole area from western continental Europe to East- and South-East Asia appear to show haplotype similarity. So it appears not only to have been a northern East-West influence but also a southern East-West influence as well.
To investigate this further I did a seperate run Chromopainter using 23k linked SNP at Chromosome 1 with a selection of individuals that had been phased together with over 2000 individuals using a high number of iterations in BEAGLE minimizing the error rate to a minimum. I used Chromopainters admixture functionality to design a admixture test using the relevant East-Asian, African and Siberian populations. As far I know from previous screening using ADMIXTURE all these individuals appear unmixed without any European admixture.
As we can see North-East Europeans appears to score low on East-Asian influence while continental Europeans from western and central Europe appear to score rather high vs the East-Asians. As expected we see the largest African like influence among the more southern populations and the North-Siberian influence in the more North-East European populations. Please note as this result is based on only 1 chromosome it doesn't always correlate 100% with the result of a whole genome analysis. There is a strong negative correlation between the East-Asian and Siberian component at -0.56 and there is even a stronger negative correlation between the Siberian and African component. The correlation between the East-Asian and Siberian component is weak at -0.17.
We can further see this using a area plot for the same data. The continental European populations from western and central Europe appear quite consistent to be closer to the East-Asian populations.
In Finestructure (from the previous run with the whole genome using superindividuals) the clustering appear to confirm what was observed above. The East-Asian influence appear rather consistent for all European populations included. In the North-East European populations this East-Asian influence appear to be lacking or less but the North-Siberian influence appear as expected from earlier analysis.
This is a seperate PCA run using Europeans, East Asians and Siberians as reference. The X axis (horizontal) shows dimension 1 and the Y-axis (vetical) shows dimension 2. The X axis shows the European vs East-Asian influence, the Y-axis shows the European vs Siberian influence.