Extremely low genetic diversity of mtDNA control region and remarkable population differentiation of Ichthyophis bannanicus (Amphibia: Gymnophiona).

It is widely accepted that the mitochondria! DNA (mtDNA) control region (CR) gene evolves more quickly than protein-encoding genes, such as ND2 and Cyt b, with few exceptions. However, some species have a different evolution pattern. In the present study, we sequenced the mtDNA CR partial sequences (454 base pairs) of 142 individuals from five sampling sites of Ichthyophis bannanicus and compared the genetic diversity and structure with the information from the NADH dehydrogenase subunit 2 (ND2) and Cytochrome b (Cyt b) genes within this species. Extremely low genetic diversity was found in the mtDNA CR compared with those of the ND2 and Cyt b genes. These results showed that the relatively mean clock rate of the CR was broadly lower than those of the ND2 (about 2.55 times) and Cyt b (about 3.14 times) genes. Despite the extremely low genetic diversity of CR, the population structure analysis identified two groups, Xishuangbanna and Northern Vietnam-Yulin-Yangchun-Deqing, which indicated that the Red River systems may have acted as gene-flow barriers for I. bannanicus.