Unveiling intraspecific variations in Notopterus notopterus and Chitala chitala through landmark-based morphometry and mitochondrial DNA barcoding

This study assessed the biodiversity of Notopteridae family by involving Notopterus notopterus and Chitala chitala because of their contribution to the ecological balance of freshwater habitats, food security, economic importance and aquaculture. Both fish species are under pressure and facing threats in their natural habitats and especially Chitala chitala is considered near threatened. Fish were sampled from the natural riverine population of the Punjab, Pakistan including Taunsa Barrage, Trimmu Head and Chashma Barrage. Fish samples were recognized morphologically, and the COI gene sequence was used to prepare them for genetic study. Maximum Likelihood (ML) trees were constructed using MEGA ۱۱ and the K۲P model. A total ۳۰ individual of N. notopterus and C. chitala (۱۵ of each) were identified by using morphometric and truss analysis. Twenty-five morphological, five meristic and ۲۷ landmarks were measured. In this study, all meristic characters of N. notopterus and C. chitala species showed non-significant (p>۰.۰۵) results and ۱۴ out of ۲۵ morphological characters of N. notopterus showed significant (p<۰.۰۵) results while C. chitala showed non-significant results in all morphological characters. Clustered analysis of N. notopterus and C. chitala showed higher mean values of the external morphological traits in Taunsa barrage and Chashma barrage, respectively. In truss study PC۱ and PC۲ revealed ۷۴.۹% and ۱۱.۲% in N. notopterus and ۸۵.۶% and ۱۱.۵% in C. chitala, respectively. The overall mean of base composition of family Notopteridae was observed as T (۲۹.۴۵%), C (۲۶.۱۷%), A (۲۷.۷۵%), G (۱۶.۶۳%). Generally, GC content (۴۲.۸%) was less than AT content (۵۷.۲%), which revealed a distinct pattern of anti-G bias. The genetic distance within two genus of family Notopteridae species were found to be ۰ while between species, the mean distance varied from ۰.۰۰۲ to ۰.۱۴۹.  Phylogenetic tree revealed the identity in the range of ۹۹% for sequences of N. notopterus and C. chitala that clustered in two clads due to two distinct genera but having same family. In this study, ۱۲ barcodes of family Notopteridae with an e-value of ۰.۰ and a maximum similarity of ۹۹–۱۰۰% with a maximum length of ۶۰۰ bp were found. The current work developed the idea for the establishment of the Pakistani fish gene bank, which is still needed, and supported the effectiveness of the COI gene for the species identification in the riverine population. Information of population structure and genetic variation obtained from current study would be helpful for planning appropriate strategies for the rehabilitation, conservation and efficient management for these two species.

کلیدواژه ها:

N. notopterus ، C. chitala ، Morphological ، Meristic ، Truss analysis ، DNA barcoding ، Phylogeny ، Conservation