Abstract:
A study was conducted to investigate genetic diversity and population structure among populations of
Nile tilapia Oreochromis niloticus (Cichlidae) in the Volta Lake of Ghana using microsatellite markers.
Four hundred (400) fish specimens were obtained from nine naturally occurring subpopulations and
one selectively bred strain, ‘Akosombo strain’. These were characterized using 15 microsatellite loci.
Twelve of the loci were multi-allelic, producing 2 to 11 alleles per locus while the effective number of
expected alleles (Ne) ranged from 2.030 to 2.855. The observed heterozygosity (Ho) and expected
heterozygosity (He) were high ranging between 0.488 - 0.594 and 0.424 – 0.502, respectively. The
Kpando-Toko populations had the highest variability (He = 0.502) whilst the Buipe population had the
least variability (He = 0.424). Gene diversity based on locus ranged between 0.1638 and 0.8673 whilst
the genetic differentiation between populations (FST) was 0.074 indicating moderate differentiation
between the populations. However, there was very high genetic variation (93%) within individuals. Nei’s
distance between the populations ranged between 0.011.and 0.133, whilst estimated overall gene flow
(Nm) and Shannon Information Index were 8.265 and 0.822 respectively. The 10 populations studied
formed two main clusters with the longest pairwise Nei’s genetic distance of 0.133 between the
Dzemeni and Kete-Krachi populations.
