earticle

영어

The genus Bufo is the most specious group in the family Bufonidae. In South Korea, there are two species of the genus Bufo : B. gargarizans and B. stejnegeri. According to previous studies on B. gargarizans, there are large genetic differentiations between the Chinese and Korean populations. Thus, to elucidate the species status and to investigate the genetic diversity of B. gargarizans in East Asia (China, Russia, North Korea and South Korea), we analyzed three mitochondrial DNA genes. To ensure a reliable estimation of the evolutionary history, partial sequences of the NADH-ubiquinone oxidoreductase chain 2 gene (ND2; 516bp), full sequences of cytochrome b gene (cyt b; 1146bp), and cytochrome c oxidase subunit I (CO1; 697bp) were analyzed in 138, 58 and 22 specimens, respectively. The phylogenetic trees constructed using the three different mitochondrial genes showed similar results with the western Chinese specimen grouping into a separate clade from the specimens from Northeast China, Russia, North Korea and South Korea (Eastern Asia clade) with a pairwise sequence divergence of 9.1% for cytochrome b and 6.9% for CO1 (K2P). Based on the partial sequence of the mitochondrial ND2 gene, 77 haplotypes were defined, consisting of three subclades of B. gargarizans in East Asia. The clade BG1 is composed of B. gargarizans in Northeast China, Russia, North Korea and South Korea. The clade BG2 and BG3 are composed of B. gargarizans in Western and Southern China. These clades are not geographically grouped. The pairwise sequence divergence between the clade BG1 and BG2 is 5.1%, and the clade BG1 and BG3 is 7.1% (K2P). The estimation of divergence time revealed that the Korean B. gargarizans in South Korea diverged during the late Miocene, approximately 7 MYA.