A study on genetic divergence of the Red squirrel Sciurus vulgaris (Rodentia: Mammalia) from six regions in Eurasia: based on cytochrome b complete sequences

Cytochrome b complete sequences (1140 bp) of Sciurus vulgaris from four regions in continental Asia (Korea, northeastern China, far-eastern Russia, and Mongolia) were obtained and analysed with corresponding complete and partial (359 bp) haplotypes of S. vulgaris, obtained from GenBank. These sequences were used to compare our and previous results from partial sequences and to examine population differentiation of S. vulgaris in Eurasia by using complete sequences and by using more numerous specimens. Based on partial sequences from ten Eurasian regions (the four regions in Asia, Japan, Portugal, western China, Russia, and northern and southern Italy), we found that S. vulgaris is composed of two clades (a minor one from southern Italy and a major one from other Eurasian regions). We considered that our results are more conclusive than previous results by other researchers, performed without using haplotypes from Korea, Mongolia, and far-eastern Russia and detected three clades (southern Italy, Russia, and other Eurasia) or two clades with one distinguishable haplotype. Moreover, we found that our results from partial sequences are less informative than those from complete sequences, indicating that cytochrome b complete sequences from Eurasia are needed in order to examine population structure of S. vulgaris. Finally, in this study on population differentiation from cytochrome b complete sequence analyses, we found that genetic divergence of six Eurasian populations, including the four Asian populations, is low, and that our results do not support the current subspecies classification, recognizing 23 subspecies