Comparative phylogeography of two commensal rat species (Rattus tanezumi
and R. norvegicus) in China: insights from mitochondiral DNA,
microsatellite and RADseq
Abstract
To explore the phylogeography of Rattus tanezumi and Rattus norvegicus
in China, 486 individuals collected from 31 localities were initially
analyzed with mitochondrial DNA and 10 microsatellite loci. Then, 123
individuals from 18 localities were subjected to 2b-RAD analyses. There
were several major findings. Although R. norvegicus is widely
distributed in China, R. tanezumi is mainly distributed in southern
China, but is currently invading northward and has occupied many regions
of northern China. Development of shipping transportation in ancient
China had an important role in expansion of these two species; except
for westward and southward colonization by land, some individuals of R.
norvegicus reached the southeast coast of China by shipping
transportation and subsequently expanded to central China; R. tanezumi
immigrated to the southeast coast of China from Southeast Asia, and then
expanded to central and western China. Before large-scale expansion
associated with human transportation, changes in Ne of these species
were closely related to climate changes. However, after immigration of
R. tanezumi into China, interspecies’ competition may have had a great
role in their population sizes, as the R. norvegicus population declined
rapidly with the increase of Ne for R. tanezumi. Analyses with 2b-RAD
sequences did not support interspecies hybridization, although
microsatellite data indicated potential gene introgression. Our study
provided a valuable framework for further investigations on the
expansion of the two dominant rat species in China. Finally, results
also indicated that previous investigations on hybridization based
solely on microsatellite data should be verified with genomic SNP data.