Genetic Diversity and Phylogenetic Analysis of Five Cultrinae Species in West Dongting Lake Based on Cytb and COI Genes

Aiming to understand the genetic diversity of <i>Culter</i> and <i>Cultrichthys</i> fishes in West Dongting Lake following the implementation of fishing ban, this study analyzed the genetic diversity and phylogeny of five Cultrinae species based on mitochondrial <i>Cytb</i> and <i>COI</i> gene sequences. For <i>Cytb</i>, 50 haplotypes were identified with high overall genetic diversity (<i>H_d</i> = 0.954, <i>π</i> = 0.04765, <i>K</i> = 53.506). Similarly, <i>COI</i> yielded 48 haplotypes (<i>H_d</i> = 0.950, <i>π</i> = 0.03251, <i>K</i> = 36.414). Interspecific comparisons revealed that <i>Culter mongolicus</i> and <i>Culter alburnus</i> exhibited the highest genetic diversity, while <i>Cultrichthys erythropterus</i> showed the lowest. Demographic inferences from neutrality tests and mismatch distribution analyses differed between markers. Based on <i>Cytb</i>, populations of <i>C. erythropterus</i> and <i>C. oxycephaloides</i> appeared to be at neutrality, whereas <i>C. mongolicus</i>, <i>C. alburnus</i>, and <i>C. dabryi</i> significantly deviated, suggesting historical expansion. Mismatch distributions supported recent expansion in <i>C. mongolicus</i> and <i>C. dabryi.</i> In contrast, <i>COI</i>-based neutrality tests indicated expansion in <i>C. mongolicus</i>, <i>C. alburnus</i>, and <i>C. dabryi</i>, with mismatch results confirming this signal for <i>C. dabryi</i>. The negative values of <i>Tajima's D</i> and <i>Fu's Fs</i> observed across all five species reflect an accumulation of low-frequency alleles within populations, which may indicate a recent rapid demographic recovery. These findings provide genetic evidence that the genetic diversity of these Cultrinae species has likely been recovering since the fishing ban took effect on 1 January 2020. Further conservation strategies are therefore recommended to promote population recovery and enhance genetic diversity.