Abstract:
ABSTRACT
The Atlantic chub mackerel Scomber colias is a small pelagic coastal
migratory species belonging to the family Scombridae. Available scientific data
reveals a gradual decline of S. colias species within Ghana’s fisheries waters as
a result of growing fishing efforts. Despite their economic value and wide
distribution in Ghana, there is lack of information on their genetic diversity.
This study aims to genetically characterize S. colias along the coast of Ghana
using microsatellite and mitochondrial DNA cytochrome b markers to ascertain
their genetic diversity. S. colias specimens were characterized using 8
microsatellite loci and 1 mtDNA cytochrome b gene. All 8 microsatellite loci
were polymorphic with 3 to 22 alleles per locus however, the effective number
of alleles (Ne) per locus and the mean number of different alleles (Na) were
1.466 and 2.054 respectively. Appreciable genetic diversity exists in the
population of S. colias. The mean observed heterozygosity (Ho) within the
population was 0.152 whilst the mean expected heterozygosity (He) was 0.244,
which means the S. colias population has decreased in size. The mean gene
diversity and PIC were 0.58 and 0.54 respectively. Growth in all the samples
exhibited isometric. The nucleotide sequences of cyt-b gene for samples
demonstrated the existence of divergence within and among the nucleotide
sequence of the S. colias population. There was high genetic divergence (FST =
0.240) within the S. colias population. However, 14% of the variance existed in
the population. Nei’s distance between the samples ranged between 0.0614 and
0.4695, with an overall gene flow (Nm) of 1.706 and Shannon Information
Index 0.406. A tanglegram generated similarities and divergences between the
genotypic and phenotypic dendrograms.
