Dispersal route of the Asian house rat (Rattus tanezumi) on mainland China: insights from microsatellite and mitochondrial DNA.

backgroundRattus tanezumi is a common commensal rat and an important host animal of bubonic plague in South China and Southeast Asia. The northward dispersal of this species in mainland China has been reported in recent decades, along with more recent intercontinental expansion. Population genetics of R. tanezumi in mainland China were studied to explain the relationship between dispersal history and the ancient and modern transportation networks of China.

resultsIn total, 502 individuals belonging to 18 populations were collected from 13 provincial areas. Nine microsatellite loci and two mtDNA sequences were analyzed. The results indicate that R. tanezumi populations from Yunnan have highest genetic diversity and populations from Tibet with lowest genetic diversity. 18 populations can be divided into four clusters, the first cluster including populations from southwest Yunnan, the second including two populations of Tibet, the third for populations from middle and east of mainland China, and the forth for two populations from north Yunnan. Both microsatellite and mtDNA data reveal that the populations from coastal areas are closely related to populations from Yunnan, whereas populations from Tibet are closely related with populations from Sichuan.

conclusionsThe results suggest that early dispersal of R. tanezumi in mainland China depended on shipping transportation, with subsequent expansion from coastal areas into Central China occurring along the Yangzi River. Further, the linkages between populations in Tibet and Sichuan point to a modern era introduction via the Chuan-Zang highway, rather than along the Tea Horse Ancient Road.