Phylogeography and Domestication of Chinese Swamp Buffalo

Water buffaloes are widespread throughout central and southern China, with the total number of 23 million (FAO, 2003), which is the third largest population of buffalo in the world. To further probe into whether swamp buffaloes were domesticated once or multiple times in China, the current study examined the complete mitochondrial DNA (mtDNA) D-loop diversity of 471 individuals representing 22 populations of 455 Chinese swamp buffaloes and 16 river buffaloes. Phylogenetic analysis revealed that Chinese swamp buffaloes could be divided into two distinct lineages, A and B. Of the two lineages, lineage A was predominant across all populations. For predominant lineage A, Southwestern buffalo populations harbor the highest genetic diversity among the three hypothesized domestication centers (Southeastern, Central, and Southwestern China), suggesting Southwestern China as the most likely location for the origin of lineage A. However, a complex pattern of diversity is detected for the lineage B, preventing the unambiguous pinpointing of the exact place of origin and suggesting the presence of a long-term, strong gene flow among swamp buffalo populations caused by extensive migrations of buffaloes and frequent human movements along the Yangtze River throughout history. In other hand, archaeological information and historical records indicated that domestication of swamp buffalo first occurred in Southwestern China in the Eastern Han period. Combined with our mitochondrial DNA analysis, the current study suggests the Southwestern China is the most likely origin center for lineage A, and may have been a primary center of swamp buffalo domestication.