Genetic variation in wild and hatchery populations of giant freshwater prawn (Macrobrachium rosenbergii) revealed by randomly amplified polymorphic DNA markers.

ABSTRACT

Sustainable improvement and conservation of any genetic resource depend on the assessment of its intra- and inter-population genetic variation. In order to estimate genetic variation in both wild and hatchery populations of Macrobrachium rosenbergii, randomly amplified polymorphic DNA (RAPD) analysis was performed. Analyses of 51 polymorphic loci amplified from genomic DNA by three decamer random primers revealed different degrees of genetic variation in two wild (Bhairab and Rupsha rivers) and hatchery-derived gher (Gher-1 and Gher-2) populations. The proportion of polymorphic loci was found to be higher in wild populations (0.90 and 0.65 for the Bhairab and Rupsha populations, respectively) than the hatchery-derived gher populations (0.29 and 0.16 for Gher-1 and Gher-2, respectively). Likewise, the river populations contained higher levels of gene diversity (0.221 and 0.179 for Bhairab and Rupsha populations, respectively) than the gher populations (0.114 and 0.045 for Gher-1 and Gher-2, respectively). These results suggest reduction of genetic variation and heterozygosity in the hatchery-derived gher populations. Inter-population similarity indices and pairwise genetic distance values showed that variation between the wild or between the gher populations were lower than those between the wild and hatchery populations. On average, 14 loci exhibited significant deviation from homogeneity in wild vs hatchery population pairs, whereas 2 and 3 loci showed heterogeneity in Gher-1 vs Gher-2 and Bhairab vs Rupsha population pairs, respectively. A genetic distance-based UPGMA dendrogram segregated river populations from the gher populations. Our study, therefore, revealed substantial levels of genetic variation between wild and hatchery populations of M. rosenbergii.