Comparative and evolutionary analysis of mitochondrial genes in Indian major carps.

Abstract

Direct sequencing of mitochondrial DNA regions such as cytochrome b, ATPase 6/8 and control region was performed to study comparative and evolutionary status of the three mitochondrial genes in Labeo rohita, Catla catla and Cirrhinus mrigala. DNA sequence alignment among species using specific software revealed comparative rates of divergence with considerably faster and more heterogeneous substitution rate for control region as compared to cytochrome b and ATPase 6/8. Despite the relatively high variability of control region, the overall levels of sequence divergence were low in coding regions. Two protein coding genes and the control region with varying degree of sequence divergence established two distinct groups which are genetically distant from each other exhibiting identical phylogenetic structure in IMCs. Closest relationship was between Labeo rohita and Catla catla indicating that they might have diverged from a common ancestral stock in genealogical lineage whereas Cirrhinus mrigala showed greater divergence with all the three DNA regions studied. Findings of this study will help to understand evolution of mitochondrial DNA genes in carps and facilitate future investigations on phylogeographic structure of Indian carps.