The Xu Shuhua/He Yungang team at Fudan University worked together to reconstruct the evolutionary history of the Li ethnic group in Hainan and trace the genetic lineage of the Baiyue population

On September 30, 2022, Molecular Biology and Evolution, a well-known international journal in the field of molecular evolution, published the collaborative research results of Professor Xu Shuhua's team from the School of Life Sciences of Fudan University, He Yungang of the Institute of Biomedical Sciences of Fudan University, and Lin Rong, a researcher at Hainan Medical College, "Tracing Bai-Yue ancestry in aboriginal Li people on Hainan.
" Island”
。 Based on whole-genome sequencing data analysis, the research team studied the genetic origin, population history and adaptive evolution of the Li people in Hainan.
Combined with the Dong Dai language groups in China and Vietnam, the genetic evolution model of the "Baiyue" ethnic group was reconstructed; It provides genetic evidence and genetic perspective
for in-depth understanding of the historical relationship between China's ancient population and the Chinese nation today.

The Li people located on Hainan Island in China are famous for their long ethnic culture and unique ethnic customs, but there are still many opinions about the genetic origin and history of the
Li people.
As early as the "History" of the Han Dynasty, it has been recorded that the Li ethnic group in Hainan has the same root and the same origin as the Baiyue clan in the Lingnan region, and previous research has also confirmed the close connection between
the Li ethnic group in Hainan and the ethnic minorities in southern China.
However, when the Li people arrived on Hainan Island today, their source and flow have still not been systematically analyzed
.
In addition, Hainan, as China's only island province located in the tropics, how Hainan's unique climate and island environment have created the ancestors of the Li people who have lived on the island for thousands of years is still an unexplored puzzle
.

The research team first combined with the various ethnic groups in southern China and Southeast Asia, confirmed that the Li ethnic group in Hainan had a close genetic relationship with the Baiyue ethnic group that used the Dong-Dai language family in history, and identified a Baiyue ancestral source enriched in the Baiyue ethnic group, and found that the ancestral source had the highest ancestral proportion among the Li people in Hainan (Figure 1).

Later, the team analyzed ancient DNA samples and found that the Hainan Li people had a closer genetic relationship
with ancient ancestors from southern China than other Baiyue ethnic groups.
Based on further analysis of genetic mixing, the research team observed that the Li had fewer mixed signals than other Baiyue ethnic groups, exhibiting the characteristics
of isolated populations.
These findings show that the Li people of Hainan, because they live in a relatively isolated island environment, have fully preserved the ancestral characteristics of the ancient Baiyue ethnic group, and have become a model group that can represent the ancestors of Baiyue in today's population
.

Figure 1 Genetic relationship characteristics of the Li people in Hainan

The research team further reconstructed
the genetic history of the Li people in Hainan.
Based on the analysis of Y chromosome data, the research team believes that the Baiyue lineage originated about 11,000 years ago
.
Analysis based on autosomal data found that around 7400, the Baiyue ethnic group experienced a decrease in effective population size; Since 4000, the Baiyue ethnic group located on land has resumed an increase in effective group size, while the Li ethnic group in Hainan continues to experience a decrease in effective group size (Figure 2
).
The research team speculated that the ancestors of the Li people of Hainan began to migrate to Hainan Island in about 4000, due to the lack of genetic exchange with the surrounding population in the isolated environment of the island, which led to the continuation of the founder effect; The Baiyue population located on land has resumed an increase
in effective population size due to genetic mixing with surrounding populations (such as Han Chinese).

Figure 2 Population genetic history of the Li ethnic group in Hainan

In addition, the research team also explored
the adaptive evolution of the Li people in Hainan.
The research team first identified the presence of selection signals in FADS1 and FADS2 associated with polyunsaturated fatty acid metabolism in the Li people of Hainan, and found that this signal was different in the north and south of East Asia, and the frequency of alleles was most frequent in the Li people (Figure 3).

At the same time, the research team also found that there are adaptive selection signals that occur on multiple malaria-related genes (such as CR1) and genes related to blood diseases such as B-cell lymphoma (such as CD3G), and that the adaptive selection signals of the Hainan Li people are significantly enriched into
pathways related to hematopoietic function.
This is most likely due to the high incidence of malaria on Hainan Island, located in the tropics, where the Li ancestors on the island have created a number of trade-offs
related to blood diseases under the pressure of malaria selection.
Finally, the research team also combined the population history and adaptive evolutionary characteristics of the Baiyue population to construct the genetic evolution model of the Baiyue population (Figure 3
).

Figure 3 Adaptive evolution and genetic evolution model of Baiyue population

Overall, this study not only conducts a systematic population genetics study of the Li ethnic group in Hainan from the whole genome sequencing data level, reveals the genetic flow and adaptive evolutionary characteristics of the Li ethnic group in Hainan, but also constructs the genetic and evolutionary model
of the Baiyue ethnic group in Chinese history in combination with the Baiyue ethnic groups in Chinese history.
This study not only provides a theoretical basis for further understanding the genetic history and genetic diversity of ethnic minorities in the southern region of China, but also provides a reference example
for the construction of genetic evolution models of terrestrial and island populations.

This research work was jointly completed
by the team of Professor Xu Shuhua of the School of Life Sciences of Fudan University, researcher He Yungang of the Institute of Biomedical Sciences of Fudan University, and researcher Lin Rong of Hainan Medical College.
Chen Hao, Ph.
D.
student at Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, and Lin Rong, researcher of Hainan Medical College, are co-first authors of this paper; Professor Xu Shuhua and Researcher He Yungang are co-corresponding authors
of this paper.
The authors involved in the study included Dr.
Yang Gao, associate researcher Lu Yan of Fudan University, and Dr.
Rui Zhang, a doctoral student at the Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences
.

This work has been funded
by the National Natural Science Foundation of China, Hainan Medical College, the Chinese Academy of Sciences Pilot Project, and the Shanghai International Human Phenotyping Group Program Municipal Science and Technology Major Project.

Original link: https://academic.
oup.
com/mbe/advance-article/doi/10.
1093/molbev/msac210/6731089