2014 Volume 9 Issue 2 Pages 99-104
The Sea of Japan is a semi-closed marginal sea where genetic break and/or speciation have been reported for some deep-sea taxa. Population structure was compared between the congeneric deep-sea flounder species Hippoglossoides dubius and H. pinetorum inhabiting the Sea of Japan and neighboring seas. Based on nucleotide sequences of mitochondrial control regions, the H. dubius population was concluded to be genetically homogeneous, while 2 genetically distinct groups were recognized among H. pinetorum. Although the rare group of H. pinetorum populates the Sea of Japan, the Yellow Sea, the Okhotsk Sea, and the northwestern Pacific, frequency was the highest in the Sea of Japan. The unique phylogeographic pattern of H. pinetorum may be attributable to secondary contact with the Sea of Japan lineage, which was isolated from other sea areas during the last glacial period. A difference in bathymetrical distribution between the two species might explain their contrasting genetic population structures.
