Population Genetic Diversity of Goldfish (Carassius auratus) from Zhejiang River Basin Based on Mitochondrial Cytochrome Oxidase Subunit I (COI) Gene Sequence

Carassius auratus is an indigenous and economically important species in China. The genetic diversity of three C. auratus populations from Tiaoxi River (TXR), Oujiang River (OJR), and Qiantangjiang (QTJ) River basin, were studied. The genetic diversity of the three populations was evaluated by mitochondrial cytochrome oxidase subunit I (COI) sequences. Totally, 225 individuals were sampled from three populations. After the sequencing of 541 bp fragments of COI gene, 536 variable sites were found and no insertion or deletion was detected. The Hap_38 (haplotype 38) was the dominant haplotype shared by 225 individuals (11.11% of all individuals) and existed in all localities. The haplotype diversity (Hd) values ranged from 0.866 to 0.931, while the values of nucleotide diversity (Pi) varied from 0.388 to 0.549. All three populations showed high genetic diversity. The pair-wise fixation index (FST) value between TXR and QTJ populations was 0.1409, which indicated that they were in middle genetic differentiation (0.05<FST<0.15), while the FST value between TXR and OJR populations, and between OJR and QTJ populations were 0.1816 and 0.1775, respectively, which indicated that they were in high genetic differentiation (FST>0.15). Based on the genetic structure, TXR and OJR populations were in the same cluster separated from QTJ population. In summary, by mitochondrial COI gene analysis, all three C. auratus populations had high genetic diversity. Populations TXR and OJR had a closer genetic distance, and they had a large genetic distance with QTJ population. This study provides a particularly important basis for C. auratus resource conservation and utilization.