Genetic Diversity between Chrysichthys Nigrodigitatus (Learrpade, 1803) from Kanji 124-137 and Asejire Dams of Randomly Amplified Polymorphic DNA (RAPD) Markers

Abstract

Randomly amplified polymorphic DNA (RAPD) markers were used to assess the genetic variation in the silver catfish (Chrysichthys nigrodigitatus) sourced from two freshwater bodies; Kainji lake (North central) and Asejire dam (South west) in Nigeria. Four primers OP-8, OPH-19, OPK-19 and LC-17 were used to amplify RAPID markers on 10 experimental fish from each population. Genomic DNA extraction and purification from caudal fin tissue was performed using ZR Genomic DNA extraction kit. The amplified fragments were ran on gel documentation system (Sygene, INGENIUS. 54 bands were generated by the four RAPD primers from the two Chrysichthys nigrodigitatus populations of which 35 were polymorphic, accounting for 64.81%. The average percent of polymorphic loci for fish samples from Kaiji was 5.7% while that of Asejire dam was 4% with percentage polymorphism of 78.5% and 49.76% respectively, indicating polymorphism in the two populations. Nei’s genetic diversity was (Ne 0.0270 ± 0.0714 and 0.3892 ± 0.1774) for the Kainji and Asejire populations respectively. Primer OPK-19 showed the best polymorphism out of the four primers with percentage polymorphs of 100% for Kainji dam and 75% for Asejire dam. Five (5) of the six (6) polymorphic loci showed significant difference at (p<0.05). A departure from homogeneity and both the relative genetic diversity (030740 ± 0.1503), genetic differentiation (Gst = 0.3334) and gene flow (Nm = 0.9996) as an average in the two populations which indicates some degree of genetic variation in the population pair. The Nei’s genetic distance so (0.1473) and genetic identity (0.8630) showed low genetic differentiation between the populations and no significant (p<0.05) correlation with geographical distances. The unweighted pair group method with averages (UPGMA) dendogram showed the Kainji population in one cluster, except two individuals which are found in one of the two sub clusters of the Asejire population thus, suggesting close genetic relationship in both populations and also reveals that the Asejire population are considerably more diverse. This findings could be use to make a future plan for conservation and management of C. nigrodigidatus in natural water bodies.