A Study Of Fish Diversity In Guizhou Province Based On DNA Barcoding

The unique water environment of Guizhou Province has nurtured abundant fish resources.According to the newly published Guizhou Fish,there are 288 fish species in Guizhou Province.However,the phenotypic characteristics of fish can change in ontogeny stages and under different environmental conditions,increasing the difficulty of morphological identification.Guizhou Province is a landlocked province with low fish farming production.With the change in lifestyle and economic growth in recent years,the increase in demand for fish has led to an increasing variety of fish products being sold in the Guiyang market,yet there is a lack of clarity in the sales ledger,making the traceability of fish products low.Currently,there are limitations in the identification of fish species in Guizhou province based on morphological methods.With the development of molecular biology,DNA barcoding technology has become an important molecular method for fish identification,diversity analysis,and discovery of cryptic species.In this study,DNA barcoding technology was used to identify fish products in Guiyang city market,and fish species in Guizhou province respectively.Verification of the feasibility of DNA barcoding in the study of fish species diversity in Guizhou Province,leading to the establishment of a DNA barcode database of fish species in Guizhou Province.The results of this study are as follows:(1)191 samples were successfully extracted and amplified from 202 fish samples collected from six municipal districts in Guiyang,yielding 171 full DNA barcodes and 191 mini DNA barcodes.The samples were divided into 4 types: 94 fresh fish samples,45 frozen fish samples,44 cooked fish samples and 8 canned fish samples.A total of 74 species of fish belonging to 61 genera in 14 orders and 39 families were identified by comparison with the homologous sequences in the database.Genetic distance results showed that the mean interspecific genetic distances were more than 10-fold with the mean intraspecific genetic distances for both full and mini-DNA barcodes.Neighbour joining trees showed that the mislabeled sample sequences clustered together with the reference sequences downloaded from Gen Bank,with a high support rate.The results of identification of fish products showed that 20.42% of samples did not match the label name,with 11.70%,20.00%,34.09% and 50.00% of fresh fish samples,frozen fish samples,cooked fish samples and canned fish samples mislabeled,respectively.This study found that among mislabeled samples,most fresh fish samples were replaced by other fish with similar morphological characteristics,high-value fish were replaced by low-value fish in processed fish products,and even some of the same fish species were labeled sold under different trade names.In conclusion,DNA barcoding can be used as a tool for the effective identification of fish products in Guiyang.(2)Fish samples collected from watersheds within Guizhou Province were morphologically identified as 159 species belonging to in 5 orders,18 families,82 genera.A total of 800 DNA barcode sequences were obtained by amplification of the CO? gene from the samples.The results of genetic distances calculated using MEGA7.0 software showed that genetic distances increased with increasing taxonomic rank and that interspecific genetic distances were 15.54 times greater than intraspecific genetic distances.Paired genetic distances calculated using the "ape" package showed that 94.81% of the morphological species had barcode gaps.These results confirm the validity of DNA barcoding in the study of fish species diversity in Guizhou Province.The number of MOTUs delimitated using RESL,ABGD,GMYC and b PTP was higher than the number of morphospecies,with a total of 176 OTUs delimitated by consensus delimitation,and no barcode overlap of all OTUs.In the species delimitated method divided results,some closely related species all shared an OTU,possibly due to recent divergence resulting in genetic differences not reaching a threshold.The mean intraspecific genetic distances of Misgurnus dabryanus,Vanmanenia pingchowensis and Schistura fasciolata have high intraspecific variability and are all classified into multiple OTUs by consensus delimitation,suggesting that there may be cryptic species in these three species.In summary,this study confirmed the effectiveness of DNA barcoding in delimitated fish species in Guizhou Province,and the results of study provided a reference basis for fish conservation and ecological research in Guizhou Province.