摘要
Corbicula japonica is the best-known bivalve inhabiting widely in brackish estuaries and lakes in Japan. Although this species has been most commercially important species of inland fisheries in Japan, the gradual decline in its production over 40 years caused not only economic problems in fishery industry but also ecological disturbances in biodiversity conservation. The aim of this study was to evaluate the reproduction structure of C. japonica populations in major fishing brackish lakes based on the genetic diversity inferred by mitochondrial DNA sequence analysis of the cytochrome oxidase c subunit I gene. Of a total of 188 C. japonica individuals collected in Lakes Shinji, Jusan, Ogawara and Abashiri, 25 haplotypes were obtained, and only the haplotype HT01 was apparent with relatively high abundance in all lakes. Minimum spanning network analysis of haplotypes showed different population structures between Lake Shinji and Lakes Jusan, Ogawara and Abashiri. In addition, pairwise population genetic distance FST and ΦST values were significantly higher in Lake Shinji than Lakes Jusan, Ogawara and Abashiri. The mismatch distribution analysis showed unimodal profile for Lakes Jusan and Ogawara and bimodal profile for Lakes Shinji and Abashiri. Those results indicate a recent population expansion in all lakes, and Lakes Shinji and Abashiri and Lakes Jusan and Ogawara maintained continuous reproduction structure and suffered to rapid population growth, respectively.
Corbicula japonica is the best-known bivalve inhabiting widely in brackish estuaries and lakes in Japan. Although this species has been most commercially important species of inland fisheries in Japan, the gradual decline in its production over 40 years caused not only economic problems in fishery industry but also ecological disturbances in biodiversity conservation. The aim of this study was to evaluate the reproduction structure of C. japonica populations in major fishing brackish lakes based on the genetic diversity inferred by mitochondrial DNA sequence analysis of the cytochrome oxidase c subunit I gene. Of a total of 188 C. japonica individuals collected in Lakes Shinji, Jusan, Ogawara and Abashiri, 25 haplotypes were obtained, and only the haplotype HT01 was apparent with relatively high abundance in all lakes. Minimum spanning network analysis of haplotypes showed different population structures between Lake Shinji and Lakes Jusan, Ogawara and Abashiri. In addition, pairwise population genetic distance FST and ΦST values were significantly higher in Lake Shinji than Lakes Jusan, Ogawara and Abashiri. The mismatch distribution analysis showed unimodal profile for Lakes Jusan and Ogawara and bimodal profile for Lakes Shinji and Abashiri. Those results indicate a recent population expansion in all lakes, and Lakes Shinji and Abashiri and Lakes Jusan and Ogawara maintained continuous reproduction structure and suffered to rapid population growth, respectively.
