Abstract: Xenophysogobio boulengeri is an endemic fish in the upper reaches of the Yangtze River, which mainly distribute in the main river from Chongqing to Shuifu and Minjiang River, a tributary of the Yangtze River. The natural resource of this species declined in recent years. In this study, mtDNA control region sequences were used to analyze the population genetic structure of X. boulengeri. A total of 38 polymorphic sites were detected from data set of 839 bp, which defined 41 haplotypes from 178 individuals. The average haplotype diversity (H_d) and nucleotide diversity (P_i) were 0.817 and 0.002, respectively. Analysis of molecular variance (AMOVA) indicated that most of the genetic variation (96.05%) existed within populations. However, pairwise AMOVA showed that F_ST values among Jiangjin population and other populations, and among Shuifu population and other populations were greater than 7%, indicating moderate genetic divergence between these populations. The mismatch distribution and neutral test revealed that X. boulengeri population had experienced an expansion event in about 0.0173 Ma. The haplotype network structure and NJ phylogenetic tree demonstrated single genetic population. Our results suggest that X. boulengeri should be wholly conserved in situ.

Key words: volcanic geology, climate change, soil microorganism, plant resource, forest ecology, Changbai Mountain, CiteSpace.