Here we present what is, to the best of our knowledge, a systematic investigation of genetic admixture between different European and Asian populations using genome-wide single nucleotide polymorphism (SNP) data from 34 populations, including seven European groups (EUR), 9 Central or South Asian groups (CSA), and 17 East Asian groups (EAS) and one Tibetan group from Tibet Plateau.Based on statistical analysis using 4 Population Test (f, we detected gene flow between Europeans and Asians were prevalent for most populations including even those from west-northern Europe and East Asia which have been generally regarded as less admixed.
Interestingly, we observed a North-to-South decline of European gene flow in East Asians, suggesting a northern path of European gene flow diffusing into East Asian populations.
Our findings contribute to an improved understanding of the history of human migration and the evolutionary mechanisms that have shaped the genetic structure of populations in Eurasia.
These shifts of PC patterns are especially obvious for most CSA, some northern EAS including Mongolian, Xibo, Hezhen, Oroqen etc., and eastern EUR including Russian, Finnish and Adygei.
We then initiated formal testing for the presence of gene flow.(a) PC plot of 1,219 samples from 35 populations that were clustered into EAS, EUR, CSA, and African.
One Oceania population Papuan, which were not considered experiencing any recent admixture with EUR or EAS, was added into our model as an out-group), and each group should fall along a line with a negative slope (equation (3)) if most groups shared same degree of drift T and W.