Abstract:This study aimed to explore the morphological adaptation and evolution characteristics of Triplophysa yarkandensis, an endemic fish in the Tarim River Basin, and further develop the proliferation and protection of native fish resources in the Tarim River Basin. This study is based on multivariate morphological metrics, and multivariate statistical analysis was conducted on 11 traditional indices and 22 framework indices of 509 samples from three geographical T. yarkandensis populations. A non-parametric test showed that, among the 31 proportional traits of the three geographic T. yarkandensis populations, 4–9/body length had significant differences (P<0.05), and 26 proportional traits such as body depth/body length had extremely significant differences (P<0.01). Principal component analysis revealed that the contribution rates of the first three principal components were 25.00%, 14.00% and 9.30%, with a cumulative contribution rate of 48.31%. The differences were primarily in the head and in front of the trunk. Cluster analysis and principal component analysis results were essentially identical. The Yarkand River and the Tarim River groups first converged into one branch that then converged into a branch with the Hotan River group. Specifically, the difference between the Yarkand River and Tarim River is small, and the difference between the Hotan River and the other two groups is large. During the verification of the built discriminant equations, the discriminant success rates were 88.48%, 88.89%, 87.73%, and the comprehensive discriminant rate was 88.37%. It is suggested that the nine morphological and proportional characters selected by discriminant analysis are feasible for the preliminary determination of different geographical populations of T. yarkandensis. The results showed that the special characteristics of the Tarim River system resulted in the morphological differences of T. yarkandensis in different river habitats, which could be distinguished effectively by multivariate analysis. However, the differences in habitat environment might be the predominant reason for the morphological differences or adaptation evolution of the fish.
