Genetic diversity and population demography of the endemic species <italic>Acrossocheilus longipinnis</italic> (Teleostei, Cyprinidae) based on mtDNA COI and cyt <italic>b</italic> gene sequences.

In this study, we investigated the population genetic structure and demographic history of <italic>Acrossocheilus longipinnis</italic> based on two mitochondrial genes (cytochrome <italic>b</italic> and cytochrome oxidase subunit I). A total of 14 haplotypes were identified for <italic>A. longipinnis.</italic> The total haplotype diversity and nucleotide diversity are 0.68586 and 0.00358, respectively, which suggest that <italic>A. longipinnis</italic> exhibits a low genetic diversity. The monophyly of <italic>A. longipinnis</italic> is not rejected by the analyses, and the species can be divided into two lineages. The analysis of molecular variance shows that more variation of genetic differentiation is present within populations than among populations. The negative values and mismatch analysis support that <italic>A. longipinnis</italic> underwent expansion and the times are estimated to be 0.07754 and 0.01977 MYA for the two lineages, respectively. These results reveal the genetic backgrounds of <italic>A. longipinnis</italic> and provide a rational basis for the implementation of more effective measures for its conservation. [ABSTRACT FROM AUTHOR]