Population Genetic Structure of Paradise Threadfin Polynemus paradiseus (Linnaeus, 1758) Revealed by Allozyme Marker

To elucidate genetic differentiation in three river populations (Tentulia, Paira and Kirtonkhola) of Polynemus paradiseus, ten enzymes encoded by seventeen presumptive loci were screened using allozyme electrophoresis marker, where five were polymorphic (Est-1*, Gpi-1*, Gpi-2*, G3pdh-2* and Mdh-1*). The mean proportions of polymorphic loci were observed 17.65, 29.41 and 11.76% in Tentulia, Paira and Kirtonkhola populations, respectively. The highest mean number of allele per locus and mean proportion of heterozygous loci per individual were observed in the Paira population (1.294 and 16.667%, respectively). The highest observed heterozygosity (H ) and average expected heterozygosity (H ) were 0.078 and oe 0.050, respectively found in Tentulia population. The highest pair-wise population differentiation (F =0.148) ST and lowest gene flow (N =1.443) were found in Tentulia-Kirtonkhola indicate the close relationship among them. m The pair-group method with arithmetic mean dendrogram of Nei's genetic distances showed that the three river populations of P. paradiseus constructed two clusters. Paira and Kirtonkhola populations made one cluster (D=0.001) and separated from Tentulia population by the genetic distance of 0.014. The results suggested that the considerable genetic variation is maintained among the natural P. paradiseus populations.