Republication from BioRxiv
Fig.1. Admixture results for K=6 showing the approximate location of the populations included in this study. The names of the populations are coloured according to their
linguistic affiliation as follows: red = Mongolic, blue = Turkic, dark green = North
Tungusic, light green = South Tungusic (Hezhen) and Manchu (Xibo), brown = Ugric,
orange = Samoyedic, black = Yenisseic, azure = Yukaghirs, maroon = Chukotko-
Kamchatkan, pink = Eskimo-Aleut, purple = Indo-European, teal = Sino-Tibetan and
Japonic. Where two subgroups are from the same geographic location, only one of the subgroups is shown (full results are presented in Fig.S1). Note that for reasons of space the location of the two distinct Yakut subgroups does not correspond to their true location. Each color indicates a different ancestry component referred to in the text as “(light) green” or European, “yellow” or Western Siberian, “blue” or Central Siberian, “pink” or Asian, “red” or Far Eastern, “dark green” or Eskimo.
Although Siberia was inhabited by modern humans at an early stage, there is still debate over whether this area remained habitable during the extremely cold period of the Last Glacial Maximum or whether it was subsequently repopulated by peoples with a recent shared ancestry. Previous studies of the genetic history of Siberian populations were hampered by the extensive admixture that appears to have taken place among these populations, since commonly used methods assume a tree-like population history and at most single admixture events. We therefore developed a new method based on the covariance of ancestry components, which we validated with simulated data, in order to investigate this potentially complex admixture history and to distinguish the effects of shared ancestry from prehistoric migrations and contact. We furthermore adapted a previously devised method of admixture dating for use with multiple events of gene flow, and applied these methods to whole-genome genotype data from over 500 individuals belonging to 20 different Siberian ethnolinguistic groups.
The results of these analyses indicate that there have indeed been multiple layers of admixture detectable in most of the Siberian populations, with considerable differences in the admixture histories of individual populations, and with the earliest events dated to not more than 4500 years ago. Furthermore, most of the populations of Siberia included here, even those settled far to the north, can be shown to have a southern origin. These results provide support for a recent population replacement in this region, with the northward expansions of different populations possibly being driven partly by the advent of pastoralism, especially reindeer domestication. These newly developed methods to analyse multiple admixture events should aid in the investigation of similarly complex population histories elsewhere.