Author(s): Megbowon I

Abstract: Genetic variation and divergence within and between the taxonomic groups of interest are usually assessed by the presence or absence of each product, which is influenced by changes in the DNA sequence at each locus. RAPD polymorphisms can occur as a result of base substitutions at the primer binding sites. This study was conducted to evaluate the genetic variation among some cichlid fishes of Epe lagoon, Lagos, Nigeria using different RAPD markers. Genomic DNA was extracted using DNA kit Nucleospin by Macherey Nagel from Germany, following manufacturer’s instructions. For DNA amplification using PCR, Primus thermocycler was used and programmed according to required specification. Primers OPC-04 (5’ CCG CAT CTA C 3’), OPAC-20 (ACGGAAGTGG) and OPI-16 (TCTCCGCCCT) which were arbitrary primers, were also used for the analysis. With OP-04 a total of 37 PCR products were scored across the gel. A range of 2-7 bands were recognized per sample. With OP-16, there was high level of similarity in the banding pattern within each species. 2-5 bands were characterized ranging from 100-600 base pairs. Concerning primer OPAC 20, 96 bands were distinctly recognized. A range of 1-5 bands were detected in each sample. From the pattern there was a great variability among the four species of cichlid. The DNA banding pattern derived from this primer showed highest similarity between Tilapia mariae and’ wesafu’. Collating the data of the three primers together, similarity coefficient was calculated. The highest value was obtained between Tilapia guineensis and Tilapia mariae (0.52992) and lowest between Tilapia mariae and Sarotherodon melanotheron (0.28925). Genetic similarities among the species of cichlids were thus detected based on bands polymorphisms which were generated by these random primers. The result showed high level of variation among genera. Within the same genera, there was polymorphism, indicating that fish within the same species are not entirely similar.

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