Range extension process of gastropods with southern origin on the Pacific coast of the eastern Japan suggesting the effects of global warming

点击翻译按钮获取中文摘要

Nucleotide sequences of a part of mitochondrial DNA(about 8500 base pair) were determined for each one specimen of Cerithidea djadjariensis from Honshu Island and Okinawa-jima Island and compared them to select three regions with high molecular evolution rates, namely, COI and ND2 genes and a region between 12S and 16S ribosomal DNAs which contains three tRNA genes and non-cording sequences. Nucleotide sequences of about 4000 base pair were also determined for Batillaria cumingi and B. multiformis. No difference in gene order was recognized among them and the order did not correspond to those of any mollusks whose gene orders have been reported. The genetic characteristics of three populations of C. djadjariensis that were recently discovered on the Pacific coast of the eastern Japan, namely, Mangokuura Lagoon, Miyagi Prefecture ; Matsukawaura Lagoon, Fukushima Prefecture ; and Shinhamako Lagoon in Tokyo Bay, were compared with other Japanese conspecific populations on the basis of the nucleotide sequences of the three regions mentioned above. Two populations in Mangokuura Lagoon and Matsukawaura Lagoon showed lower genetic diversity than and no significant differentiation from populations in western Honshu and Kyushu. The foundation of these populations might be attributed to range expansion along the coast, probably due to global warming. On the other hand, the population in Tokyo Bay, which was rediscovered in 2001 on an artificial tideland, was shown to be genetically different from all other Japanese populations whose genetic structures have been analyzed, which suggests that this population was founded by human-mediated introduction- Slightly increase of frequency of the Kuroshio-type individuals of Batillaria cumingi around Mangokuura Lagoon between 2000 and 2006 might be attributable to northward range expansion of them due to global warming.