Paternal genetic structure of the Qiang ethnic group in China revealed by high-resolution Y-chromosome STRs and SNPs (original) (raw)

Forensic Population Genetics - Research Paper

Paternal genetic structure of the Qiang ethnic group in China revealed by high-resolution Y-chromosome STRs and SNPs

Introduction

The Qiang ethnic group is a minority mainly distributed in Sichuan Province, with its population size in Sichuan taking up 95.92 % (296931/309576), according to the results of the sixth National Population Census in 2010 (http://www.stats.gov.cn/tjsj/pcsj/rkpc/6rp/indexch.htm). One-third of the Qiang ethnic group is located in the Beichuan Qiang Autonomous County [1]. The Qiang ethnic group is one of the nomads in China. Historically, The Qiang people mostly lived nearby the mountainous areas of Minjiang River. They were a branch of ancient Qiang people, of whom the former ancient Qiang people were believed to be the progenitors of what is now known as Han Chinese. The latter ancient Qiang people were ancestors of Han, Qiang, Tibetans, Yi, Bai, Naxi, Pumi, Lisu, Lahu, Jinuo, Achang, Jingpo, Dulong, Nu, and Tujia ethnic groups. Qiang linguistically derived from Sino-Tibetan Tibeto-Burman Qiangic language subfamily, and they called themselves “Er’ma”. The name “Qiang” appeared very early in history, since the oracle bone inscription recorded abundant contacts and conflicts between Qiang and Han people from 1600 B.C. to 1046 B.C. in the Shang Dynasty [2]. The Qiang ethnic group originally lived on the prairie, and later began to migrate because of natural disasters and wars. One branch migrated southward to Rezi (now belonging to Songpan County), and because of the wars, they continued to migrate and multiply and were distributed along Minjiang River and some areas of Peijiang River, including Songpan County, Mao County, Wenchuan County, Li County and Heishui County. From the literature and territorial settings of Han Dynasty, the Qiang People had been active along Minjiang River during the Han Dynasty [2]. There were frequent conflicts between Qiang, Han, and Hulu People in Western Jin Dynasty, and the government control of this area in Eastern Jin Dynasty was extremely weak. In Tang Dynasty, with the rise of Tubo forces, the Qiang area became a contested territory between Tang and Tubo for a long time. The Qiang people continued to suffer from the chaos of wars and at the same time accepted a large amount of Tibetan culture. During the implementation of Tusi System (established in Ming Dynasty), the exchanges between different ethnic groups were frequent, and the social and economic development of the Qiang People was remarkable. At the end of Ming Dynasty, many Han People began to move into the Qiang’s territory, bringing in the production technologies of Han Nationality. In the middle of the seventeenth century, the court of Qing Dynasty gradually weakened the power of the native chieftains (chief of a tribe under Tusi System) and implemented the policy of “abolishing native chieftains and appointing government officials”. The Qiang area gradually entered the feudal landlord economy, and the exchanges between Qiang and Han Nationalities were further strengthened.

There were several presumptions about the origin of the Qiang ethnic group. The Qiangic languages in western Sichuan are believed to be the oldest branch of the Sino-Tibetan linguistic family, and therefore, all Sino-Tibetan populations might have originated in western Sichuan (WSC) [3]. According to previous studies, the Qiang had the greatest diversity of Sino-Tibetan populations, supporting the view of this population being the oldest in the family [4]. The Qiang population has been found with the highest STR diversity of O3-M117 (what is now defined as O2a2b1a1-M117 by the International Society of Genetic Genealogy, ISOGG), supporting the ancient tales that the Han Chinese clearly trace their origin to the Qiang people (Wang, Z. H. (1994) History of Nationalities in China (in Chinese). Beijing, China: Social Sciences Press.). Furthermore, ancient DNA revealed genetic connections between early Di-Qiang (Di and Qiang were historically combined to be one group) and Han Chinese [5], [6]. Archaeological findings also suggested that the Yangshao Culture of approximately 7000 years ago had its origin in the region of the Qiang people [6], [7]. Previously, the genetic feature of 29 Y-chromosome microsatellites of the Qiang ethnic group has been reported [1]. The result revealed that the Qiang people has a smaller genetic distance from the Han people compared to other reference population.

Genetic variations on Y chromosome are informative for deciphering human evolutionary process from the aspect of male lineages. Y chromosome is uniparental and passed directly from fathers to sons. The non-recombining portion of Y chromosome (NRY) undergoes no genetic recombination when passing to the next generation, and thus its diversity only derives from mutation. It is, therefore, easier to identify the difference between populations. These characteristics make NRY a medium for reconstructing population demographic and evolutionary changes. Few studies have reported the Y chromosomal polymorphisms of the Qiang ethnic group or Di-Qiang populations and the marker sets were comparatively small [4], [8], [9]. Sichuan is of great importance for its variety in populations. However, the population structure of the Qiang ethnic group in this region is not adequately studied. The population size of the Qiang ethnic group ranks fourth in Sichuan, with other three ethnic groups being Han, Yi, and Tibetans. The paternal genetic structure of the Qiang remained unclear. Recently, Wu et al. reported the allele frequencies of 29 Y-chromosome short tandem repeats (Y-STRs) of 242 unrelated Qiang males, mainly exploring the forensic parameters of these Y-STRs [1]. Further genetic insight into the Qiang ethnic group remains to be uncovered. To what extent did gene flow between Qiang and Han, Qiang and Tibetans happen? Did the Qiang have any genetic admixture or affinity with other populations in China? Based on the minimal phylogeny [10] and the advanced version of haplogroup tree, we focus on Y-chromosome single nucleotide polymorphisms (Y-SNPs) to investigate a fine-scale Y-chromosome phylogenic tree to reveal the paternal population structure of the Qiang ethnic group residing in Sichuan Province. A total of 422 unrelated male individuals were recruited and genotyped by a combination of multiplex genotyping systems, a high-resolution panel containing 233 Y-SNPs and 29 Y-STRs. The Y-SNPs were sequenced by the SNaPShot sequencing, and the Y-STRs were typed by capillary electrophoresis (CE). Median-joining tree analysis, as well as Y-STR comparison within haplogroups, was performed to yield new insight into the genetic structure of the Qiang ethnic group.

Section snippets

Samples

A total of 422 male individuals in the Qiang ethnic group were involved in the Y-SNP and Y-STR analysis. The samples were collected after receiving written informed consent and with the approval of the Ethics Committee in Sichuan University (K2019018). Buccal swab samples were collected using FTA cards (Whatman, Clifton, NJ, USA). The inclusion criteria for participation were males of the Qiang ethnic group whose ancestors have lived in Beichuan Qiang Autonomous County for at least three

Y-chromosomal haplogroup distribution

Y-SNPs used in this study was shown in Supplementary Table S1. Haplotype and haplogroup data generated in this study were listed in Supplementary Table S2. All samples belonged to the main haplogroup C, D, J, N, O, Q, or R (Supplementary Fig. S1), which covered four dominant haplogroups (accounting for 92.87 % of the East Asian Y chromosomes), O-M175, D-M174, C-M130 (not including C5-M356), and N-M231 [28]. Haplogroup O-M175 (N = 312) was the most predominant haplogroup in the Qiang ethnic

Haplogroup-specific microvariants

For haplogroup-specific microvariants or null alleles, twenty-one intermediate alleles occurred in the process of Y-STR genotyping, of which 14 were at locus DYS518. Interestingly, these fourteen microvariants were all two nucleotides smaller or bigger. Without exception, all of them belonged to haplogroup Q-M242, which is the ancestral haplogroup of the native American-specific haplogroup Q1a3a-M3 [28], [31]. These two findings were consistent with Lang's study, where 32 individuals with

Conclusion

The Qiang ethnic group has the highest genetic diversity when it came to haplogroup diversity. Although having a part of individuals in haplogroup D, the Qiang had totally different terminal haplogroups compared to Tibetans, Yi and Japanese. Gene flow was observed in the Qiang and Han ethnic group, and the considerable haplogroup O percentage showing the genetic similarity with Han Chinese. At the same time, the higher genetic diversity implied that the Qiang might be older than Han ethnic

CRediT authorship contribution statement

Mengyuan Song: Conceptualization, Methodology, Data curation, Investigation, Writing – original draft, Formal analysis. Zefei Wang: Data curation, Investigation. Qiang Lyu: Validation. Jun Ying: Validation. Qian Wu: Data curation, Investigation. Lanrui Jiang: Data curation, Investigation. Fei Wang: Visualization. Yuxiang Zhou: Data curation, Investigation. Feng Song: Validation. Haibo Luo: Validation. Yiping Hou: Conceptualization, Methodology, Supervision, Writing – review & editing, Funding

Conflict of interest

The authors declare that they have no conflict of interest.

Acknowledgements

Thanks for the volunteers who participate in this study. This study was supported by grants from the National Natural Science Foundation of China (81672096, 82202614 and 81871532). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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