DNA Barcoding of Fish Species Diversity in Guizhou, China

Abstract

Guizhou is an important ecological barrier in the upper reaches of the Yangtze River and the Pearl River basins with abundant fish species. However, fish from these regions are threatened by anthropogenic activities, including overfishing and habitat destruction. Here, we assessed the fish diversity including more than half of the species from the region using DNA barcoding (partial sequence of cytochrome c oxidase subunit I (COI) gene). We obtained 800 mitochondrial COI barcode sequences from 82 genera, 18 families and 8 orders of fishes. The average Kimura two-parameter (K2P) distances within species and genera were 0.35% and 5.44%, respectively. The average interspecific distance was 15.54 times higher than the mean intraspecific distance. Moreover, DNA barcodes revealed 175 operational taxonomic units (OTUs) based on consensus demarcation schemes. Barcoding gaps were detected in 94.81% of morphospecies. Three fish species (Schistura fasciolata, Vanmanenia pingchowensis, and Misgurnus dabryanus) have considerable intraspecific variability, and each was divided into multiple molecular operational taxonomic units (MOTUs) using molecular definition methods (Automatic Barcode Gap Discovery, Refined Single Linkage, General Mixed Yule Coalescent, and Poisson Tree Processes), possibly indicating the occurrence of cryptic species. Altogether, our study reveals the complex diversity of fish species in Guizhou Province, serving as a reference for the conservation and monitoring of fish species in this region.