Multiple Domestication Centers Revealed by the Geographical Distribution of Chinese Native Pigs

Previous studies have shown that Southeast Asian pigs were independently domesticated from local wild boars. However, the domestication of Chinese native pigs remains a subject of debate. In the present study, phylogenetic analysis of Chinese native pigs was performed by screening for haplotypes inferred from a phylogenetic tree of pig mitochondrial DNA (mtDNA) sequences based on sequence-specific mutations. A total of 2466 domestic pigs formed 124 haplotypes and were assigned to four clades. Clade A comprised pigs distributed mainly in the Qinghai-Tibet Plateau and its surrounding areas; these pigs clustered into three groups. The pigs of clade B were mainly from the Mekong River Basin in Yunnan Province and had been exposed to genetic infiltration from European populations. Clade C comprised pigs mainly from the middle and lower reaches of the Yangtze River. The pigs of clade D were distributed mainly at the intersection of Yunnan, Sichuan, and Gansu provinces east of the Hengduan Mountains (YSGH). Compared with wild boar, at least three domestication centers and one expansion center of pigs in China were detected. Among the four centers detected, two were for Tibetan pigs and were in the Qinghai-Tibet Plateau and at the YSGH intersection, and the other two were in the Mekong River Basin in Yunnan Province and the middle and downstream regions of the Yangtze River.