Genetic Differentiation of Carassius auratus and C. cuvieri by the Cytochrome C Oxidase I Gene Analysis

Abstract

It is estimated that 27 bony fish species have been introduced into Korean freshwaters for aquaculture and the enhancement of fishery resources. Among them, Carassius cuvieri has completely adapted and is widely distributed throughout Korean freshwater ecosystems. In this study we investigated the genetic relationship between C. cuvieri and the closely related native crucian carp species Carassius auratus. Nucleotide sequence variation within the mtDNA cytochrome c oxidase I (COI) gene was used to study the genetic divergence and phylogenetic relationships among the species and to identify their taxonomic status in the family Cyprinidae. We compared partial COI gene sequences (630 base pairs) from three populations of C. auratus and three populations of C. cuvieri. A total of 46 variable sites were identified from 163 individuals, yielding 23 haplotypes. The two species showed very close genetic relationship with 95% sequence identity in the COI gene, the frequency and distribution of haplotypes showed clear separation, suggesting divergent evolution of these two species. Therefore, despite the morphological similarity and phylogenetic closeness, the populations of these two species should be regarded as separate management units in the ongoing recovery program.