ABSTRACT
Aims: To reveal the genetic variability of wild and captive populations of the Indian major carp, mrigal (Cirrhinus cirrhosus) based on microsatellite DNA markers analysis. Study Design: Three rivers namely the Halda, the Padma and the Jamuna were selected under wild population category and three hatcheries such as Brahmaputra Hatchery of Mymensingh, Raipur Government Hatchery, Luxmipur, and Sonali Hatchery, Jessore were selected under the captive population category. Place and Duration of the Study: Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Mymensingh from July 2005 to June 2008. Methodology: DNA was extracted from fin clips of a total of 180 fish, 30 from each of the six populations. Five microsatellite markers MFW1, MFW2, MFW17, Barb54 and Bgon22 were amplified by polymerase chain reaction for each DNA sample and resolved on denatured polyacrylamide gel and visualized by silver nitrate staining. Results: Three of the five loci were found to be polymorphic in all the six populations. The observed (HO) and expected heterozygosity (HE) ranged from 0.233 to 0.633 and 0.406 to 0.664 respectively. The FIS values ranged from 0.032 to 0.635 indicating deficiency in heterozygosity. Except the Raipur Hatchery stock, the other five populations showed nonconformity to Hardy- Weinberg Expectation at least in one locus. Significant population differentiation was observed between the Halda-Jamuna, Jamuna-Brahmaputra Hatchery, Jamuna-Raipur Hatchery and the Padma-Raipur Hatchery population pairs. The UPGMA dendrogram based on genetic distances resulted in two major clusters: the Halda river and the Raipur Hatchery population were in one cluster and the remaining four populations were in the other cluster. Conclusion: The study, as a whole, revealed low levels of genetic variation in terms of allelic richness and heterozygosity in the three major rivers and three selected hatchery stocks of C. cirrhosus in Bangladesh.