Genetic diversity and structure of Opsaridium microlepis along Lake Nyasa, Tanzania

Abstract

Opsaridium microlepis is a fish species that serves as a source of revenue and protein to most people living near Lake Nyasa. However, the population of this species has witnessed a worrisome decline, leading the International Union for Conservation of Nature (IUCN) to classify it as a threatened fish species. The current work used partial mitochondrial cytochrome oxidase subunit I (COI) sequences to investigate the genetic diversity, effective population size, and structure of O. microlepis along the Lake Nyasa areas of Tanzania. The findings indicated that Kafyofyo had the highest nucleotide diversity (π = 0.20%) and haplotype diversity (h = 0.78), while Katumba had the lowest nucleotide diversity (π = 0.08%). The lowest haplotype diversity (h = 0.50) was recorded at Katumba and Mbambabay. The molecular analysis indicated significant differences across the subpopulations investigated (Overall PhiST (ΦST) = 0.093, P < 0.05). The mean Sum of Square deviation (SSD), Harpending's raggedness index (HRI), Tajima's D (D), and Fu's Fs (Fs) were 0.014, 0.157, 0.108, and -0.88680 respectively and neither the mismatch distribution nor the neutrality test findings were significantly different from zero. The mismatch distribution supports the idea of sudden population expansion. Consequently, the effective population size estimates are large for sampling sites with higher genetic diversity. Thus, the current study's findings can serve as a foundation for long-term strategic plans to conserve and manage populations of O. microlepis in areas with low genetic diversity and effective population size.