Estimation of phylogenetic relationships among Japanese brown frogs from mitochondrial cytochrome b gene (Amphibia: Anura).

We investigated phylogenetic relationships among five species of Japanese brown frogs by the analysis of nucleotide sequences in the cytochrome b gene of mitochondrial DNA (mtDNA). The sequence of the 251-base pairs, which cover approximately 22% of the cytochrome b gene, was determined by PCR-Direct sequencing method. Phylogenetic relationships were analyzed by UPGMA, neighbor-joining, maximum-likelihood, and maximum parsimony analyses. The sequences only slightly varied within one population of Rana japonica. Intraspecific variation in sequences varied among species, and R. tagoi showed more pronounced variation than did R. ornativentris. Rana japonica and R. tagoi share 2n = 26 chromosomes with each other, but the former was closer to R. pirica and R. ornativentris, both with 2n = 24, than to the latter. Phylogenetic relationships estimated from the nucleotide sequence of the cytochrome b gene generally conformed to the idea hitherto proposed chiefly on the bases of morphological and ecological evidences.