The founder stock of a captive breeding program is prone to changes in genetic structure due to inbreeding and genetic drift. Genetic characterization of the founder population using suitable molecular markers may help monitor periodic changes in the genetic structure in future. To develop benchmark information about the genetic structure we analyzed six microsatellite loci in the Brodbank collections of rohu (Labeo rohita) originated from three major rivers-the Jamuna, the Padma and the Halda. A total of 28 alleles were detected in 90 individuals with an average of 4.6 alleles per locus. The average observed heterozygosity ranged from 0.655 to 0.705 and the expected heterozygosity ranged from 0.702 to 0.725. The mean F IS values were 0.103, 0.106 and 0.018 for the Jamuna, Padma and Halda fishes respectively. The population pair-wise F ST values ranged from 0.0057 to 0.0278. Structure analysis grouped the fishes of the three rivers into two clusters. The numbers of half-sib families were 5, 5 and 4 and the numbers of full-sib families were 12, 10 and 18 for the Halda, Jamuna and the Padma samples respectively. Bottleneck was detected in all the river samples. We recommend to collect more fish from different locations of the major rivers to broaden the genetic variability of the founder stocks of the Brood bank.
Keywords: Bottleneck; Brood bank; Genetic variation; Major carps; Microsatellite; Sib-ship.