Population structure and evolutionary history of the greater cane rat (Thryonomys swinderianus) from the Guinean Forests of West Africa.

Grasscutter (Thryonomys swinderianus) is a large-body old world rodent found in sub-Saharan Africa. The body size and the unique taste of the meat of this major crop pest have made it a target of intense hunting and a potential consideration as a micro-livestock. However, there is insufficient knowledge on the genetic diversity of its populations across African Guinean forests. Herein, we investigated the genetic diversity, population structures and evolutionary history of seven Nigerian wild grasscutter populations together with individuals from Cameroon, Republic of Benin, and Ghana, using five mitochondrial fragments, including D-loop and cytochrome b (CYTB). D-loop haplotype diversity ranged from 0.571 (± 0.149) in Republic of Benin to 0.921 (± 0.013) in Ghana. Within Nigeria, the haplotype diversity ranged from 0.659 (± 0.059) in Cross River to 0.837 (± 0.075) in Ondo subpopulation. The fixation index (FST), haplotype frequency distribution and analysis of molecular variance revealed varying levels of population structures across populations. No significant signature of population contraction was detected in the grasscutter populations. Evolutionary analyses of CYTB suggests that South African population might have diverged from other populations about 6.1 (2.6-10.18, 95% CI) MYA. Taken together, this study reveals the population status and evolutionary history of grasscutter populations in the region.

DNA Barcoding Silver Butter Catfish (Schilbe intermedius) Reveals Patterns of Mitochondrial Genetic Diversity Across African River Systems.

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.