Phylogenetic relationships of silver crusian carp Carassius auratus gibelio, C. auratus cuvieri, crucian carp Carassius carassius, and common carp Cyprinus carpio as inferred from mitochondrial DNA variation

PCR-RFLP analysis of the ND3/ND4L/ND4 and 12S/16S rRNA regions and nucleotide sequence variation of the cytochrome b gene were used to study the mtDNA divergence in species of the family Cyprinidae, to examine the phylogenetic relationships of the species, and to identify their taxonomic status. The results indicated that an ancestral form diverged into silver crucian carp and crucian carp after its separation from the common carp lineage. The divergence of continental Carassius auratus gibelio and Japanese C. auratus cuvieri occurred more recently. Two well distinguishable mtDNA phylogroups, suggesting divergent evolution, were observed in continental C. auratus gibelio populations. The divergence was possibly related to the formation of two silver crucian carp groups with different types of reproduction, triploid gynogenetic and diploid gonochoric. At the same time, the results supported the high probability of current genetic exchange between the forms. In view of these findings and high morphological similarity of the two forms, they were not considered to be separate species.