Preliminary study on genetic differences between two species of finless porpoises, genus Neophocaena, with lack of genetic divergence between two subspecies of the narrow-ridged finless porpoise, TV. asiaeorientalis: cytochrome b sequence analyses

摘要

Using samples from bycaught finless porpoises, cytochrome b sequences were analysed and phylogcnctie trees were constructed. The aims were to: (I) determine genetic divergences within the genus Neophocaena; (2) examine interspecific divergences between N. asiaeorientalis and N. phocaenoides', and (3) examine intraspecific divcrgcncc between N.a. asiaeorientalis and N.a. sunameri. For this purpose, complete cytochrome b sequences for 12 N.a. sunameri specimens, collcctcd from fishery markets at Pohangin southeastern Korea, were obtained, and these sequences were compared to the corresponding partial (402bp) and complete (1,140bp) sequences of Neophocaena, obtained from GenBank. From a maximum likelihood tree with the partial sequences of the two Neophocaena species, two clades were detected, corresponding to the two species, with average gcnctic distance of 1.64%, four fixed site differences (1.00%), and a G** value of 0.64, although we did not examine the specimens from Southeast Asia and contiguous South China Sea. Furthermore, from the complete sequences, we recognised a lack of gcnctic divergence between the two subspecies of N. asiaeorientalis, with a value of 0.06 and two pairs of identical sequences between them, indicating that our resultsdo not support currcnt subspecies classification. Thus, wc newly found that our cytochrome b sequencing results are useful for the examination of interspecific and intraspeeific divergences in Neohpocaena, although further genetic analyses with additional specimens of Neophocaena across its distributional range are necessary to confirm the findings in this study.