A review of genetic intra- and interspecific relationships of deep-sea Buccinum and Neptunea species around Japan (with special reference to the Sea of Japan)

Abstract

Abstract:The Sea of Japan is a marginal sea surrounded by narrow, shallow straits which became isolated from neighboring waters when the sea level fell during the Pleistocene glacial periods. In order to understand the influences of such paleoenvironmental changes on the formation of populations of marine organisms in the Sea of Japan, deep-sea whelks (genera Buccinum and Neptunea (Buccinidae)) are appropriate materials considering their low dispersal abilities through direct development. Deep-sea whelks are also important marine species for fisheries in the Sea of Japan. However, several taxonomical problems due to morphological variations and lack of knowledge about gene flows among local populations in deep-sea whelks may lead to inappropriate fisheries management. We and my collaborators examined the genetic inter-and intraspecific relationships of deep-sea Buccinum and Neptunea species by means of molecular markers with samples from various stations around Japan (mainly from the Sea of Japan). We found some intriguing genetic structures closely related to their characteristic reproductive mode and paleoenvironmental changes in the Sea of Japan. In addition, by comparing inter-and intraspecies relationships of some Buccinum species, I clarified some novel taxonomical aspects of these species. Here, I review these genetic structures of deep-sea whelks and describe the future direction of phylogeographical approaches to deep-sea organisms in the Sea of Japan.

Genetic divergence of Argis lar and A. hozawai, distinct sibling species of deep-sea crangonid shrimp from the Sea of Japan

“…During the Pleistocene glacial periods in the Sea of Japan, the surface water became brackish, and the bottom water was anoxic (reviewed in Itaki et al 2004). It has been reported that these major environmental changes resulted in reduction of populations of many deep-sea taxa (Kojima et al 2001, Iguchi 2010. As the vertical distribution of both A. lar and A. hozawai is relatively deep (160-260 m; Uji 1994), the two shrimps may have experienced similar demographic responses as a result of environmental changes.…”