Evaluating genetic differentiation in wild populations of the Indian major carp, Cirrhinus mrigala (Hamilton–Buchanan, 1882): Evidence from allozyme and microsatellite markers

The population structure of Cirrhinus mrigala from different riverine locations in India was investigated using allozyme and microsatellite loci. C. mrigala samples were obtained from ten rivers belonging to Indus, Ganges, Brahmaputra and Mahanadi basins. Seven (29.2%) out of 24 allozyme loci and seven microsatellite loci were polymorphic, including five from our earlier work. Significant deviation (P < 0.05) from the Hardy–Weinberg expectations were evident for two allozyme loci: G6PDH⁎, XDH⁎, and two microsatellite loci: MFW17, R-12F, in different samples. Both markers types demonstrated concordant results and various estimates revealed genetic variability within the subpopulations but surprisingly low level (θ = 0.015 to 0.02) of genetic differentiation among C. mrigala from different river samples. AMOVA analysis also indicated low differentiation among subpopulations. Common ancestry in the prehistoric period and possible exchange of individuals between rivers in different river basins such as Indus and Ganges could have been responsible for the observed low level of genetic differentiation among wild mrigal populations.