Abstract
Mongolians dwell at the Eastern Eurasian Steppe, where is the agriculture and pasture interlaced area, practice pastoral subsistence strategies for generations, and have their own complex genetic formation history. There is evidence that the eastward expansion of Western Steppe herders transformed the lifestyle of post-Bronze Age Mongolia Plateau populations and brought gene flow into the gene pool of Eastern Eurasians. Here, we reported genome-wide data for 42 individuals from the Inner Mongolia Autonomous Region of North China. We observed that our studied Mongolians were structured into three distinct genetic clusters possessing different genetic affinity with previous studied Inner Mongolians and Mongols and various Eastern and Western Eurasian ancestries: two subgroups harbored dominant Eastern Eurasian ancestry from Neolithic millet farmers of Yellow River Basin; another subgroup derived Eastern Eurasian ancestry primarily from Neolithic hunter-gatherers of North Asia. Besides, three-way/four-way qpAdm admixture models revealed that both north and southern Western Eurasian ancestry related to the Western Steppe herders and Iranian farmers contributed to the genetic materials into modern Mongolians. ALDER-based admixture coefficient and haplotype-based GLOBETROTTER demonstrated that the former western ancestry detected in modern Mongolian could be recently traced back to a historic period in accordance with the historical record about the westward expansion of the Mongol empire. Furthermore, the natural selection analysis of Mongolians showed that the Major Histocompatibility Complex (MHC) region underwent significantly positive selective sweeps. The functional genes, alcohol dehydrogenase (ADH) and lactase persistence (LCT), were not identified, while the higher/lower frequencies of derived mutations were strongly correlated with the genetic affinity to East Asian/Western Eurasian populations. Our attested complex population movement and admixture in the agriculture and pasture interlaced area played an important role in the formation of modern Mongolians.
Highlights
The vast Eurasian steppe zone stretching from Hungary in the west to Mongolia and northeastern China in the east has witnessed a dynamic demographic history
In a principal component analysis (PCA) of Eurasian individuals, modern and ancient Eastern and Western Eurasian populations were separated into PC1 and PC2 split Eastern Eurasians along a north-south cline with Tungusic and Mongolic speakers who connecting with the west-east Eurasian cline (Figure 1A)
The proportions of ancestry components associated with Eastern or Western Eurasians were well concordant with the results of PCA
Summary
The vast Eurasian steppe zone stretching from Hungary in the west to Mongolia and northeastern China in the east has witnessed a dynamic demographic history. Ancient DNA findings from Western Eurasian Steppe showed the massive continental-scale steppe population migrations, admixture, and turnover since the Early Bronze Age (Allentoft et al, 2015; Mathieson et al, 2015; Damgaard et al, 2018; Wang et al, 2019). 2200–1700 BCE) in the Late Bronze Age brought related culture into the Eastern Steppe and substantially contributed to the gene pool of the Eastern Steppe, forming the genetic heterogeneity with west-east admixture cline of Western Steppe-related ancestry. Even though the Western Steppe-related ancestry fluctuated in ancient Mongolia populations, modern Mongolian groups still show some extent of affinity with Western Eurasian-related populations and show genetic structure with different proportions of the Western Eurasian-related ancestry (Bai et al, 2018; He et al, 2019; Jeong et al, 2019; Zhao et al, 2020)
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