MrBayes phylogeny with posterior probability values based on D-loop sequences from Mus musculus. The scale bar represents nucleotide substitutions per site. Clades and subclades are indicated. There are three main subclades in M. m. castaneus: CAS1, CAS2, and CAS3. All M. m. castaneus mice in mainland China are within the CAS1 clade (dark green branch), and there is no primary subclade for M. m. musculus (purple branch). Most samples from Taiwan (TW, the largest island in eastern China, which is close to Fuzhou, Fujian Province) are within CAS2, while samples from Fuzhou (FZ) and Jinmen (JM, Fujian Province) are in CAS1. KY, NZ, IND, and PAK are used as abbreviations for Kenya, New Zealand, India, and Pakistan, respectively.