DNA Barcoding of Mullets (Family Mugilidae) from Pakistan Reveals Surprisingly High Number of Unknown Candidate Species

Ariba Hasan,Shabir Ali Amir,Pirzada Jamal Ahmed Siddiqui,Jean-Dominique Durand

doi:10.3390/d13060232

Abstract

The mullets are a widespread group of ecologically and economically important fishes of disputed taxonomy due to their uniform external morphology. Barcoding and phylogenetic studies from various locations around the world largely highlighted the species diversity underestimation using morphological criteria used to establish the taxonomy of the family. Here, we investigated the mullet species diversity from Pakistan, a biogeographic area where nearly no mullet species were genetically characterized. Morphological examination of 40 mullets reveals 6 known species (Planiliza macrolepis, P. klunzingeri, P. subviridis, Crenimugil seheli, Ellochelon vaigiensis, and Mugil cephalus). Using a references DNA barcode library, the DNA barcode-based species identification flagged eight molecular operational taxonomic units (MOTUs) belonging to five genera (Crenimugil, Ellochelon, Mugil, Osteomugil, and Planiliza). Among these MOTUs, only one was already present in Barcode of Life Data system, all other representing new Barcode Index Numbers (BIN). These results emphasize the importance of the recognition of cryptic species and the necessity to re-evaluate the overall diversity by the genetic characterization of different species of this family. DNA barcoding is an effective tool to reveal cryptic species that need to be considered in conservation and management measures of fisheries in Pakistan.

Highlights

It is largely acknowledged that the current fish taxonomy based on the variation of morpho-anatomical characters greatly underestimated the species diversity [1,2]
The increasing number of new species detected through DNA barcoding suggests that the biodiversity level is greatly underestimated using solely the classical system of morphology-based identification
Delimitation of molecular operational taxonomic units (MOTUs) within the members of family Mugilidae found along the Pakistani waters was determined for the first time

Summary

Introduction

It is largely acknowledged that the current fish taxonomy based on the variation of morpho-anatomical characters greatly underestimated the species diversity [1,2]. Phylogenetic, and DNA barcoding studies flagged independent evolutionary lineages in widely geographically distributed species that are more and more recognized as cryptic species or at least as candidate species pending further taxonomic investigations [1,3,4,5,6,7,8,9]. From a more pragmatic perspective, incorrect identification of commercially important species may lead to overexploitation and contribute to fish stock depletion [13]. In this context, the DNA barcoding method proved to be a useful and independent approach based on the variation of morphometric and meristic characters for species identification [14]. Instead of observable and definite morphological differences, mitochondrial cytochrome c oxidase subunit I (COI) gene has been used to resolve many taxonomic ambiguities [15,16]

Methods

Results

Discussion

Conclusion