| Background: Mitochondrial DNA (mtDNA) harbors a series of characteristics, such as matrilineal inheritance, absence of recombination, rapid rate of mutation, and high level of population-specific polymorphisms, which make it a very useful genetic marker for studying the human evolution and migration history of human ethnic groups. The matrilineal mode of inheritance enables researchers to trace related lineages back through time, highlighting the maternal ancestry of a population, without the confounding effects of biparental inheritance and recombination. Chaoshan, the eastern part of Guangdong Province, is a littoral located at the southeast of the Mainland China with its east abutting on Fujian. The whole region covers the areas of Shantou, Chaozhou, and Jieyang. People residing in this area speak in a unique dialect and have distinct lifestyle and are defined as Chaoshanese. According to history records, before 214 BC the main aboriginal living in the Chaoshan littoral was Minyue population. After the Qin and Han Dynasties, Han inhabitants of north-central China migrated into the Chaoshan area, gradually assimilated the preexisting aboriginals and eventually became the major population in the Chaoshan area. Our previous genetic study of Chaoshan population based on the Human leucocyte antigen (HLA) and autosomal Short tandem repeat (STR) markers revealed that Chaoshanese, while clustering in general with the southern China-related Han Chinese, had the highest affinity to the Mainland Minnanese, but separated distinctively from the northern Hans. Our study based on autosomal STR also showed that the gene pool of Chaoshan population consisted of a large majority of Central plain Han and a little Southern native origin.Objective: To investigate the genetic relationship between Chaoshan population and other Chinese populations from the perspective of maternal inheritance, and to analyze the genetic composition of Chaoshan population's matrilineal gene pool.Method: Sequences of mtDNA hypervariable segment (HVS-1 and HVS-2) and the COⅡ/tRNALys intergenic deletion were investigated , and the mtDNA haplogroup frequencies were calculated in 120 unrelated Chaoshan individuals. Moreover, the mtDNA hypervariable segment region 1 sequence and haplogroup frequency data of other Chinese populations were collected and used for population comparison. Population relationships were investigated by phylogenetic analysis and principal component analysis. In addition, the admixture analysis was performed to estimate relative contribution of northern Hans and southern natives to Chaoshan population.Result: For Chaoshan population:haplotype diversity (h) was 0.992 for HVS-1 and 0.942 for HVS-2;nucleotide diversity (π) was 0.02153 for HVS-1 and 0.01049 for HVS-2;the 9-bp deletion frequency was 18.33%;the overall frequency of southern native dominant haplogroups was slightly higher than the overall frequency of northern Han dominant haplogroups. The results of phylogenetic analysis and principal component analysis revealed thatChaoshan population clustered with other southern Hans. In matrilineal gene pool of Chaoshan population, genetic composition of southern natives and northern Hans took up about 50% respectively. In addition, the results of phylogenetic analysis and principal component analysis also suggested that the distinction between north and south population in China was noticeable Conclusion: Mitochondrial DNA hypervariable segments in Chaoshan population had a high level of polymorphism. Chaoshan population had the genetic characteristics of southern Han and the matrilineal genetic composition of Chaoshan population consisted of both northern Han and southern native origin. There was significant genetic difference between Southern and Northern populations in China. |
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