keywords: RAPD, Primer, polymorphic, monomorphic, characterization
This study assessed the suitability of Random Amplified Polymorphic DNA (RAPD) technique for the characterization of Oreochromis niloticus, Heterobranchus longifilis, and Heterotis niloticus from the Niger-Benue River confluence in Lokoja, Kogi State, Nigeria. RAPD-Polymerase Chain Reaction amplifications reactions were carried out on DNA extracted fromthe caudal fin tissue of the fish species using five primers (OPA-02, OPA-06, OPA-11, OPAE-10 and OPD-14) that produced consistent bands. It was observed that the intensity and number of amplified bands detected varied depending on the primers used and fish samples. A total of seventy clear, distinct and sharp bands were produced by the five primers. Sixty-two out of the seventy bands were polymorphic while the remaining eight bands were monomorphic. These findings reveal the presence of sufficient genetic variability for the discrimination of the fish species. The 100% polymorphism produced by OPA-02 indicated that the primer is the best for discriminating the three fish species in this study. Similarity coefficient range of 0.33 to 0.45 recorded also indicated presence of genetic diversity and therefore supporting the suitability of the technique for fish species characterization in the Confluence River. The dendrogram puts Oreochromis niloticus and Heterotis niloticus together in the same group while Heterobranchus longifilis was separated into a different group. This indicates that Oreochromis niloticus and Heterotis niloticus are genetically more related compared to Heterobranchus longifilis. This study provided a baseline molecular database for species identification and characterization for conservation and management of fish species population in the Confluence River.