Genetic Characterization of Atlantic Chub Mackerel (Scomber Colias) in Ghana

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.