Genomic insight into the population structure and admixture history of Tai-Kadai-speaking Sui people in Southwest China

Sui people, which belongs to the Tai-Kadai-speaking family, remain poorly characterized due to a lack of genomic-wide data. To infer the fine-scale genetic structure and putative genetic sources of the Sui population, we genotyped 498,655 genome-wide single nucleotide polymorphisms (SNPs) using SNP-arrays in 58 Sui individuals from seven indigenous populations in Guizhou province and Guangxi Zhuang Autonomous Region, Southwest China. We applied principal component analysis (PCA), ADMIXTURE, pairwise Fst genetic distance, f-statistics, qpWave and qpAdm analysis to infer the genetic patterns of Sui people. Our results revealed that Guangxi and Guizhou Sui people showed a strong genetic affinity with southern China minorities, especially Tai-Kadai and Hmong-Mien speaking groups. They derived a large part of Southern East Asian-related ancestry (45.3%~63.8%), supporting Sui came from southern China originally. We also observed the genetic substructure within Sui groups: Guizhou Sui people was relatively homogeneous, showed similar genetic profiles with Tai-Kadai related populations, such as Maonan. While Sui people in Yizhou and Huanjiang of Guangxi might receive unique, additional gene flows after the divergence within other Sui populations, respectively. Guangxi Huanjiang Sui showed the strongest relationships with Hmong-Mien speaking groups, especially Huanjiang Miao and Hmong. Guangxi Yizhou Sui harbored more Sino-Tibetan-speaking related ancestry than other Sui groups. These findings help us better understand the demographic history of Tai-Kadai speaking Sui people and their interaction with neighboring populations in Southern China.