Population genetic structure of cobia Rachycentron canadum Linnaeus 1766 along the Indian coast using molecular markers

Abstract

Cobia, Rachycentron canadum is an economically important prime candidate newlinespecies with emerging global potential for mariculture in Asian countries. They newlinebelong to the monotypic family Rachycentridae, under the order Perciformes. Despite newlinethe importance of this species as a valuable marine resource in aquaculture, the newlineavailable genetic data of R. canadum remain limited in the Indian coast. The present newlinestudy aims to evaluate the genetic diversity and population structure of R. canadum newlineusing mitochondrial (Cytb gene and ATPase 6/8 genes) and nuclear markers newline(microsatellite) across Indian waters. This is the first wide-ranging holistic approach newlineto determine stock structure of R. canadum along Indian waters using both molecular newlinemarkers. Fresh 220 samples of R. canadum were analysed from four population viz. newlineVeraval, Cochin, Chennai and Kolkata. Mitochondrial DNA markers indicate a low newlinelevel of genetic differentiation i.e., entire population exists as single stock along the newlineIndian coast. However, genetic data derived from microsatellite markers suggests a newlinelow but significant differentiation with a fine scale structuring with three separate newlinestocks- Veraval; Cochin; Chennai and Kolkata along the Indian waters. This study newlineshowed that the combination of molecular markers with different modes of newlineinheritance and mutation rates is able to disentangle the complex patterns of newlinepopulation structure and dynamics of a highly migratory marine fish, the cobia. The newlinedemographic parameters determined using mitochondrial markers and bottleneck newlineanalysis using microsatellite data revealed that the population of cobia is genetically newlinestable in the Indian waters. The estimate of expansion of the population was inferred newlineto have occurred 0.035 to 0.046 Myrs ago, corresponding to the late Pleistocene newlineperiod. Comparison of R. canadum microsatellites along Indian, Pacific and Atlantic newlineoceans revealed a clear significant geographic sub-structuring of cobia populations newlineacross three oceans i.e., three main populations Atlantic Oc