The sequence variation of the mtDNA control region was analyzed for Myodes rufocanus and M. rex and compared interspecifically and regionally (Hokkaido mainland and Rebun and Rishiri Islands). On the mainland, the observed number of haplotypes (the observed γ-diversity) was 300 (n = 1028) and 46 (n = 136) for M. rufocanus and M. rex, respectively. The estimated γ-diversity, including unobserved haplotypes, was 613.3 and 150.4 for M. rufocanus and M. rex, respectively. The average haplotype richness from 52 sampling plots (α-diversity) of M. rufocanus was 10.1, which was higher than twice that of M. rex (4.6) from 15 plots. The β-diversity showed no interspecific difference. The higher γ-diversity of M. rufocanus on the mainland was explained by having more local populations with higher α-diversity than M. rex. The observed γ-diversity was higher for M. rex than M. rufocanus on Rebun Island, whereas it was similar on Rishiri Island. The α- and β-diversity did not show statistically significant differences between the species on both Rebun and Rishiri Islands, although β-diversity appeared higher for M. rex than M. rufocanus on Rebun Island. These interspecific and regional variations were interpreted based on the historical vegetation changes in the study area.
Published online 27 December, 2023; Print publication 30 April, 2024