RETRACTED: SEQUENCE ANALYSIS OF MITOCHONDRIAL CYTOCHROME C OXIDASE I GENE IN CATFISHES: AN INSIGHT INTO BARCODING AND PHYLOGENY

The standard methodology of DNA barcoding consists of clustering a taxonomic group using the Neighbour-joining (NJ) clustering method, which utilizes the divergence gap between species as a yardstick of species differentiation. With this approach, the present study is framed to decipher the divergence trend in catfish species - Clarias batrachus, C. gariepinus, Heteropneustes fossilis, Sperata seenghala, Wallago attu and Rita rita. The partial segment of the mitochondrial cytochrome c oxidase I subunit gene was used as the molecular marker of investigation. The intraspecific and interspecific divergence values were compared where a considerable gap was found between them. The average intraspecific divergence was found to be < 1%, while the average interspecific divergence found in the range of 16-24% which encompasses the divergence even at the family level. The NJ clustering has differentiated these species and has also shown phylogenetic insights as well. The species relatedness which appeared in NJ clustering was then reconfirmed using the Maximum likelihood (ML) approach with bootstrap support to trace their phylogenetic relationship. Interestingly, both NJ and ML clustering were found parallel, which assured the presence of phylogenetic signals in NJ tree too. Our study has successfully shown the role of intraspecific and interspecific divergence in species differentiation in catfishes, and simultaneously highlights the appearance of phylogenetic relationships in the NJ tree. A more comprehensive way of sampling is also discussed that could assist in looking deep into the divergence role to differentiate higher taxonomic levels.