Fig. 3 a) Ancestry coefficients for a) two clusters (K=2), b) three
clusters (K=3), and c) four clusters (K=4).
Four geographically distinct groupings with sharp species boundaries can
be distinguished and assigned to the given regions from Western to
Eastern Eurasia. When two clusters were set (K=2), cluster 1 (Western
Siberia) was genetically distinct from cluster 2 (Eastern Siberia) (Fig.
3 a). Cluster 1 spreads out from Northern to Southern Siberia over the
entire zone of the West Siberian Plain. Cluster 2 runs from across the
Taymyr Peninsula in the northern part of Siberia through Yakutia to
Bolshoi Toko in Southern Yakutia. Between cluster 1 and cluster 2, the
Yenisey River and the Central Siberian Plateau form a clear boundary.
Under three clusters (K=3), the former Eastern Siberian cluster divides
into two distinct clusters (Fig. 3 b): cluster 2 (Yakutia) and further
east in the region of Chukotka cluster 3 (Chukotka). Under four clusters
(K=4), the Yakutian cluster is divided into a western and an eastern
cluster (Fig. 3 c). Between cluster 3 (Western Yakutia) and cluster 4
(Eastern Yakutia), the Lena River is visible, which is located parallel
to the Verkhoyansk Range.
Many individuals (63%) can be assigned with 75–100% confidence to a
definite cluster (Fig. 5). When comparing the admixture plots with the
spatial distribution of the clusters (Fig. 3 c), it becomes apparent
that the individuals in the core area of the clusters have a clear
affiliation to exclusively one cluster and the individuals at the edge
of the clusters have a fragmented affiliation to different clusters.
This is also apparent in the pie charts on a map provided in Appendix
S5.