Genetic diversity and population demography of narrow-ridged finless porpoises from South Korea on the basis of mitochondrial DNA variation: Implications for its conservation in East Asia

The narrow-ridged finless porpoise, Neophocaena asiaeorientalis, is a small cetacean inhabiting the coastal waters of Taiwan, East China, Korea, and Japan, and is threatened by anthropogenic pressures. We analyzed the mitochondrial control region of N. asiaeorientalis from Korean waters to better understand the genetic diversity, population structure, and demographic history through comparison with previously reported sequences from Japan and China. The network and phylogenetic analyses illustrated that few common haplotypes were centrally located, and that most of the unique haplotypes were on the edges of the branches. Moreover, the estimates of fixation indices and gene flow revealed significant genetic differentiation among the regions in East Asia. The mismatch distribution suggested a population expansion in the late Pleistocene. We propose that the current genetic variation in N. asiaeorientalis in East Asia was shaped by historical demographic expansion during the late Pleistocene. The N. asiaeorientalis of Korean waters has the highest diversity observed with the sampling available at this time. However, the abundance of N. asiaeorientalis in Korean waters has rapidly declined and the species needs protection from bycatch.