Search

Cichlids are among the economically important which serve as a source of food for people ‎around the world. A deep understanding of the population structure and genetic diversity of ‎cichlids are vital for initiation of conservation policies and sustainable aquaculture. There is ‎paucity of information on the patterns of genetic variations among and within cichlids in ‎North-central Nigeria. This study, therefore, investigated population genetic structure of ‎Coptodon zillii, Oreochromis niloticus, and Hemichromis fasciatus collected from different ‎freshwater bodies in North-central Nigeria. Genomic DNA was extracted, and five highly ‎polymorphic RAPD primers were used for RAPD-PCR amplification and genotyping of the ‎fish. Genetic polymorphism within and between the three tilapia species were examined. ‎Percentages of polymorphism loci, pairwise population matrix, analysis of molecular variance ‎‎(AMOVA), and genetic distances of cichlid populations were determined using standard ‎methods, and dendrograms were constructed using an un-weighted pair group method of ‎arithmetic mean (UPGMA). Overall, percentages of estimated molecular variance within and ‎among C. zillii, H. fasciatus and O. niloticus populations were 5% and 95%; 4% and 96% and ‎‎13% and 87%, respectively. Our results suggest that the three cichlids have close evolutionary ‎relationship and there were no distinct genetic differences on the basis on sampling locations. ‎C. zillii and H. fasciatus are more genetically closer than O. niloticus. This study concludes that ‎RAPD is useful in studying the population genetic structure of cichlids. This study therefore ‎recommends conservation of genetic pool of cichlid species through proper maintenance and ‎restoration of polluted habitat to guarantee sustainable fishery production. However, markers ‎such as microsatellite DNA can be assayed in further studies for better results‎.

The silver butter catfish (Schilbe intermedius) is widely distributed across African river systems. To date, information on its mitochondrial genetic diversity, population structure, and historical demography are not well-established. Herein, we combined newly generated mitochondrial cytochrome c oxidase (COI) subunit I gene sequences with previously published COI sequences in the global databases to reconstruct its phylogeography, population genetic structure, and historical demography. Results from the mtDNA phylogeography and species delimitation tests (Cluster algorithm – Species Identifier, Automatic Barcode Gap Discovery and Poison Tree Process model) revealed that S. intermedius comprises at least seven geographically defined matrilines. Although the overall haplotype diversity of S. intermedius was high (h = 0.90), results showed that East (Kenya) and West (Nigeria) African populations had low levels of haplotype diversity (h = ~0.40). In addition, population genetic polymorphism and historical demographics showed that S. intermedius populations in both East and West Africa underwent severe contractions as a result of biogeographic influences. The patterns of genetic diversity and population structure were consistent with adaptive responses to historical biogeographic factors and contemporary environmental variations across African river systems. This is suggestive of the influence of historical biogeographic factors and climatic conditions on population divergence of S. intermedius across African river systems. Given our discovery of previously underappreciated diversity within S. intermedius, we recommend that this species be considered for increased conservation and management.

The wide application of titanium dioxide nanoparticles and phosphorus in the manufacturing of many industrial products mainly used in agricultural sector has resulted in the release of considerable amounts of these compounds into freshwater aquatic ecosystem. These compounds may cause some unexpected effects to aquatic organisms. This study assessed the binary effects of Titanium nanoparticles (nTiO

The demand for manufactured products and the derivatives of nanomaterials and non essential metals continue to increase, and as a consequence their presence in fisheries and aquaculture has therefore become a major concern for the risks to which our environment is exposed. The bioaccumulation profile of binary compounds (Titanium dioxide nanoparticles and lead) and their effects on the feeding behaviour of copepods were assessed in a simplified food chain including, the freshwater alga Chlorella ellipsoides and the cyclopoids copepods sp. Our results indicated that Pb and TiO