Genetic diversity and genetic structure of <italic>Coilia nasus taihuensis</italic> populations in Jiangsu Province based on mtDNA control region sequences

Abstract

<italic>Coilia nasus taihuensis</italic> is the dominant species in freshwater lake fish community of the lower reaches of the Yangtze River and Huaihe River, and it is also an important fishing target. In order to better understand the genetic diversity and genetic structure of <italic>C</italic>. <italic>nasus taihuensis</italic> populations in freshwater lakes, we analyzed the genetic variation of mitochondrial DNA loop region among six wild lake populations (Ge Lake, Tai Lake, Gaoyou Lake, Baima Lake, Hongze Lake and Luoma Lake) of <italic>C</italic>. <italic>nasus taihuensis</italic> in Jiangsu Province. By means of PCR amplification and sequencing, the full length of D-loop sequences were obtained and then used for genetic diversity and genetic structure analysis. A total of 103 variable sites and 92 haplotypes were detected in 214 individuals. The haplotype diversity and nucleotide diversity of six populations varied from 0.726 to 0.951, from 0.005 52 to 0.005 52, respectively. Meanwhile, the haplotype diversity and nucleotide diversity of total populations were 0.857 and 0.007 29, respectively. Results suggested that the haplotype diversity of <italic>C</italic>. <italic>nasus taihuensis</italic> was high, while the nucleotide diversity was low. AMOVA analysis indicated that 6.20% of the molecular variation occurred between populations, and 93.80% occurred within populations, suggesting that great genetic differentiation existed among certain populations. The genetic differentiation index (<italic>F</italic>_st) value of total populations was 0.061 99 (<italic>P</italic><0.01), and the pairwise <italic>F</italic>_st values among populations indicated that there was significant genetic differentiation between Ge Lake population and the other five populations, and there was no significant genetic differentiation among the five populations. The neighbor-joining phylogenetic tree and parsimony network of haplotypes indicated that individuls of <italic>C</italic>. <italic>nasus taihuensis</italic> were divided into two lineages without correlation with geographical populations. The neutrality tests suggested <italic>C</italic>. <italic>nasus taihuensis</italic> population had undergone population expansion in evolutionary history, and the population expansion appeared in 0.089-0.16 million years ago. The research results showed that the genetic diversity of <italic>C</italic>. <italic>nasus taihuensis</italic> was abundant in Jiangsu Province. The Ge Lake population owned multiple peculiar haplotypes, and there were significant genetic differences between Ge Lake population and the other five lake populations. So, the Ge Lake population should be managed as an independent unit, and the other five populations should be managed and utilized as a whole unit.