Abstract:Neosalanx taihuensis is an icefish endemic to China and mainly distributed in the middle and lower reaches of the Yangtze and Huaihe rivers and affiliated lakes. In recent years, the natural resources of this species have declined markedly. To assess the genetic diversity and genetic structure of wild populations of N. taihuensis, we amplified and sequenced mitochondrial cyt b gene sequences from 144 individuals from four lakes [Tai Lake (TH), Gaoyou Lake (GY), Hongze Lake (HZ) and Luoma Lake (LM)] in Jiangsu Province. The results detected 29 polymorphic nucleotide sites and 25 haplotypes among the cyt b sequences of the 144 individuals. Haplotype diversity was 0.682±0.037, and nucleotide diversity was 0.00231±0.00021. The GY population showed the highest genetic diversity among the four populations and the TH population the lowest. Analysis of molecular variance showed that 71.53% of the molecular variation was among populations and 28.47% was within populations, with the molecular variation originating mainly from interpopulation differences. A pairwise fixation index (Fst) revealed significant differences between the LM population and the TH, GY, and HZ populations, and no significant differences among the TH, GY, and HZ populations. A phylogenetic tree and a minimum spanning network showed that the 25 haplotypes form two distinct geographical clades: one consisting of the TH, GY, and HZ populations, and the other consisting of the LM population. The results of a neutrality test showed that the values of Tajima’s D and Fu’s Fs were negative, and had significant differences. The mismatch distribution was unimodal, which indicated that the four N. taihuensis populations had experienced population expansion. As the genetic diversity of the N. taihuensis populations is low, measures to protect its wild resources are warranted. The TH, GY, and HZ populations should be protected and managed as a whole population and the LM population as a distinct population.
