Genomic Insights Into the Genetic Structure and Natural Selection of Mongolians

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.

Genomic insights into the genetic structure and population history of Mongolians in Liaoning Province

“…We also found there were genetic differences among Mongolians, Fuxin Mongolians had less ARB and MP hunter–gatherer-related ancestry and Western Eurasian-related ancestry relative to Baotou Mongolian and Outer Mongolian, and Bijie Mongolians in Guizhou Province had more Sino-Tibetan-related ancestry and Southern-related ancestry than other Mongolian people. These results further supported the conclusions of previous studies ( He et al, 2021 ; Yang et al, 2021 ).…”

“…In this study, we merged our newly genotyped 36 individuals’ data with the Affymetrix Human Origins (HO) array dataset ( Patterson et al, 2012 ) and recently published population data from Baotou Mongolian and Bijie Mongolian ( Chen et al, 2021 ; Yang et al, 2021 ) to constitute a dataset containing 52,403 SNPs that was used to perform principal component analysis (PCA), F ST , admixture, TreeMix, and ALDER. Also, we merged newly genotyped data with the 1240K dataset from the Reich Lab ( https://reich.hms.harvard.edu/allen-ancient-dna-resource-aadr-downloadable-genotypes-present-day-and-ancient-dna-data ) to obtain a dataset with a larger number of SNPs (139,592 SNPs) for performing f 3 -statistics, f 4 -statistics, qp Wave/ qp Adm, and qp Graph.…”

“…Steppe pastoralists have a genetic influence on East Asian populations, but their genetic contributions are limited (Ning et al, 2019;Wang et al, 2021a;Yang et al, 2021). The influence of steppe pastoralists on the genetic formation of MP populations was discontinuous (Wang et al, 2021a), but the steppe pastoralist-related ancestry has persisted in Northwest China since the Early Bronze Age (~3000 BCE) (Ning et al, 2019;Wang et al, 2021c;Zhang et al, 2021a), and the steppe pastoralistrelated ancestry also exists in the genetic makeup of modern populations in South Siberia and Western and Northern China (Feng et al, 2017;He et al, 2021;Ma et al, 2021).…”

“…The Eurasian Steppe zone is the largest steppe zone in the world that stretches from Eastern Europe through Mongolia to Northeast China, Bronze-Age Yamnaya Steppe pastoralists expanded eastward through the Eurasian Steppe, and then Afanasievo, Andronovo, and Sintashta cultures, which are related to the Yamnaya culture, established, respectively ( Haak et al, 2015 ; de Barros Damgaard et al, 2018 ; Ning et al, 2019 ). Steppe pastoralists have a genetic influence on East Asian populations, but their genetic contributions are limited ( Ning et al, 2019 ; Wang et al, 2021a ; Yang et al, 2021 ). The influence of steppe pastoralists on the genetic formation of MP populations was discontinuous ( Wang et al, 2021a ), but the steppe pastoralist-related ancestry has persisted in Northwest China since the Early Bronze Age (∼3000 BCE) ( Ning et al, 2019 ; Wang et al, 2021c ; Zhang et al, 2021a ), and the steppe pastoralist-related ancestry also exists in the genetic makeup of modern populations in South Siberia and Western and Northern China ( Feng et al, 2017 ; He et al, 2021 ; Ma et al, 2021 ).…”

“…This reveals Mongolians gradually mixed with the local indigenous people along with their migration ( Chen et al, 2021 ; He et al, 2021 ). Also, there is a different admixture history in western and eastern Chinese Mongolians, the western Mongolians receive more genetic influence of western Eurasians, and the Eastern Mongolians possess more Neolithic YRB- and ARB-related ancestry ( He et al, 2021 ; Yang et al, 2021 ). Ancient Mongolia is formed by multiple tribes, every ancient Mongolian tribe experience a different origin, exchange, and admixture history, and their descendants live in different regions, which may be one of the reasons why genetic differences existed in modern Mongolians.…”