Genetic differentiaton of populations of Oreochromis niloticus in Nigeria

The differentiations in the genomes of selected cultured and wild populations of Oreochromis niloticus from New Bussa and Ikorodu were assessed in this study. Twenty specimens of O. niloticus were obtained from Kainji Lake and Usman farms at New Bussa and also Majidun River and Toga farms in Ikorodu. DNA was obtained from clipped fins using CTAB based procedure with the purified DNA being analysed in a multigene gradient thermocycler using 8 microsatellite markers. The amplicons generated were subjected to fluorescent genotyping and the corresponding allele scored. The data obtained was used to determine genetic parameters such as inbreeding coefficient, observed and expected heterozygosities, allelic richness, effective number of allele and Nei genetic distance. The average expected heterozygosities for Kainji Lake (CAPK) was 0.7488 while that of Usman farms (CUPN) was 0.7043 in New Bussa. Also, the average expected heterozygosities for Majidun River (CAPI) was 0.5953 and that of Toga farms (CUPT) was 0.4533 respectively. On the average, three populations (CAPK, CUPN and CAPI) were inbred while one population (CUPT) was outbred. The analysis of genetic distance among the populations showed two major clusters; CAPK and CUPN and then CAPI and CUPT with CAPK and CUPN being significantly differentiated However CAPK and CAPI largely overlap while CUPN and CUPT are differentiated.