Biology subjects

Danquah, E.

Publications and source records attributed to Danquah, E..

7 recordsLinked to original sources

bioRxiv2025

Advancing global DNA-referencing of bushmeat in African tropical forests: a tool for identifying trade hotspots and dynamics in western and central Africa

The bushmeat trade in Africa is a largely unregulated activity that drives the unsustainable exploitation of wild terrestrial vertebrates--an issue often coined the bushmeat crisis. We build on a four-gene mitochondrial DNA-typing approach to develop an unprecedented reference database framework for effectively tracing the bushmeat trade in tropical Africa. Our dataset comprises over 2,500 samples collected over a 13-yr period across 10 African countries and two European airports. Relying on an expert analytical pipeline and [~]8,700 nucleotide sequences, we identified 96% of samples to the species-level. In contrast, we estimated that conventional two-gene approaches would have yielded 18-26% erroneous or inconclusive taxonomic assignments. DNA-typing refined > 50% of field identifications, with refinement reaching 92-95% for highly processed carcasses seized in Europe. Leveraging expanded taxonomic representation, we empirically refined the genetic species thresholds applied to bushmeat and provide a reproducible pipeline for using our expert reference database from NCBI. Overall, we identified 133 species--mostly mammals--with one-third listed as of conservation concern, and uncovered cryptic diversity evidence within several taxa. Our results also demonstrated the value of community ecology indexes for large-scale monitoring of the bushmeat trade. While national markets generally mirrored regional biodiversity patterns across tropical Africa, Benin emerged as a notable outlier and a key wildlife trade hotspot. We advocate for the integration of community ecology frameworks into surveillance efforts to guide more effective, regionally tailored mitigation strategies. Continued, standardized sampling is essential to broaden taxonomic coverage and enhance detection of cryptic biodiversity in genetic bushmeat monitoring.

genetics↗

bioRxiv2024

Local genetic adaptation to habitat in wild chimpanzees

How populations adapt to their environment is a fundamental question in biology. Yet we know surprisingly little about this process, especially for endangered species such as non-human great apes. Chimpanzees, our closest living relatives, are particularly interesting because they inhabit diverse habitats, from rainforest to woodland-savannah. Whether genetic adaptation facilitates such habitat diversity remains unknown, despite having wide implications for evolutionary biology and conservation. Using 828 newly generated exomes from wild chimpanzees, we find evidence of fine-scale genetic adaptation to habitat. Notably, adaptation to malaria in forest chimpanzees is mediated by the same genes underlying adaptation to malaria in humans. This work demonstrates the power of non-invasive samples to reveal genetic adaptations in endangered populations and highlights the importance of adaptive genetic diversity for chimpanzees. One-Sentence SummaryChimpanzees show evidence of local genetic adaptation to habitat, particularly to pathogens, such as malaria, in forests.

evolutionary biology↗

bioRxiv2023

Conservation genetics of the white-bellied pangolin in West Africa: a story of lineage admixture, declining demography and wide sourcing by urban bushmeat markets

During the last 40 years, the volumes of African pangolins feeding the illegal wildlife trade have dramatically increased. We conducted a conservation genetics survey of the most traded African species, the white bellied pangolin (WBP; Phataginus tricuspis), across three West African countries including Guinea, Cote dIvoire and Ghana. Our study combining mitochondrial DNA (mtDNA) sequencing and microsatellites genotyping is the first to reveal a global pattern of admixture between two of the six mitochondrial lineages as previously delimited within WBP. We found a signature of isolation-by-distance and a lack of population genetic structuring, supporting the idea that WBP may have underestimated dispersal abilities. Levels of genetic diversity were low compared to central African lineages, reinforcing the picture of genetic pauperization shared by West African WBP. We observed a 85-98% decline in the effective population size of WBP occurring c. 3200 to 400 ya, with current numbers (520-590) at the lower end of the conservative thresholds for minimum viable population size. The microsatellites markers were powerful enough to differentiate between individuals and identify replicated samples, confirming the utility of this approach in tracing the pangolin trade. Genetic diversity estimates confirmed that Yopougon, the main bushmeat market from Abidjan (Cote dIvoire), was fed by a large trade network as confirmed by vendors reporting 10 different sources situated 62-459 km away from the market. We conclude that WBP distributed in the Upper Guinean Block should be considered a single management unit of high conservation concern, as impacted by genetic diversity erosion, drastic decline in effective population size and wide range sourcing for feeding urban bushmeat markets. Given the genetic admixture pattern detected within WBP from West Africa, we advocate for a multi-locus strategy to trace the international trade of the species.

genetics↗

bioRxiv2021

Fishing for survival: importance of shark fisheries for the livelihoods of coastal communities in Western Ghana

Small-scale shark fisheries support the livelihoods of a large number of coastal communities in developing countries. Shark meat comprises a cheap source of protein and is traded locally in many parts in developing countries, while the skins, oil, and fins are exported to the international market. This study addresses a gap in literature regarding the importance of elasmobranchs to key shark-fishing communities and the degree to which trade in shark products (meat and fins) vary in time and among fishing communities in Ghana. We interviewed 85 fishers and traders involved in shark fisheries in Axim, Dixcove, and Shama communities using semi-structured questionnaires. Fishing was the primary source of income and accounted for 58.5% of the total household income of respondents. Other important economic activities were fish processing (16.0%), fish retailing (13.3%), and small businesses (2.5%). One-third and often two-thirds of respondents generated between 80-100% of their income from shark fisheries: Axim (65%), Dixcove (68%), and Shama (35%). Shark meat consumption was common among fishers and traders and represents a substantial source of protein in the diet of the study communities. Hammerhead sharks (Sphyrna spp) and Bull Shark (Carcharhinus leucas) have the most valuable fins and meat. Further, 75% and 95% of fishers and traders, respectively, see fishing and trading of shark meat as their last safety-net and, therefore, tend to be satisfied with their jobs. Non-fishing related livelihood streams including small businesses and transportation were the major fallback activities both fishers and traders preferred to rely on if there is a ban on the exploitation of sharks in Ghana. Overexploitation of these species will compromise food ecosystem functionality and security. Thus, any shark management strategy needs to urgently restraint mortality to sustainable levels, which, in the short-term, must take into consideration the preferred livelihood fallback options outlined by fishers and traders, and implement them to ensure the long-term benefits of the intervention.

zoology↗

bioRxiv2021

Local ecological knowledge, catch characteristics and evidence of elasmobranch depletions in Western Ghana

Local Ecological Knowledge has the potential to improve fishery management by providing new data on the fishing efforts, behavior, and abundance trends of fish and other aquatic animals. Here, we relied on local knowledge of fishers to investigate ecological factors that affect elasmobranch fishers" operations and the changes in stock status of sharks and rays from 1980 to 2020 in five coastal communities in Ghana. Data were gathered from fishers using participant observation, interviews, focus group discussions, and participatory rural appraisal techniques. The results revealed fisher"s understanding of six main ecological variables, which are mostly applied to enhance their fishing operations: season and weather conditions, lunar phase, bait type, presence of seabirds and fish movement, color of seawater, and sea current. These ecological features have been applied over the years to enhance fishing operations as well as maximize fisher catch. Fishers reported a profound decline in shark and ray catch from 1980 to 2020 and attributed the decline in size, number, and composition of their catch to overfishing and Illegal, Unreported and Unregulated (IUU) fishing operations. In general, most shark and ray species were abundant in 1980 but have been severely depleted as of 2020, with the exception of Blue Shark (Prionace glauca) and Devil rays (Mobula spp), which were reported to be common by the interviewed fishers. The first species depleted were the Thresher sharks (Alopiidae), Tiger Shark (Galeocerdo cuvier), Blackchin Guitarfish (Glaucostegus cemiculus), and Lemon Shark (Negaprion brevirostris), which were depleted early in the 2000s. The next depletions of Hammerhead sharks (Sphyrnidae), Bull Shark (Carcharhinus leucas), Sand Tiger Shark (Carcharias taurus), Stingrays (Fontitrygon spp), and Spineback Guitarfish (Rhinobatos irvinei) occurred in the 2010s. We found Local Ecological Knowledge of fishers to be surprisingly consistent with scholarly knowledge and call for their inclusion in research, decision-making and management interventions by biologists and policy makers.

zoology↗

bioRxiv2020

Predicting range shifts of African apes under global change scenarios

AimModelling African great ape distribution has until now focused on current or past conditions, whilst future scenarios remain scarcely explored. Using an ensemble forecasting approach, we predicted changes in taxon-specific distribution under future scenarios of climate, land-use and human population changes. LocationSub-Saharan Africa MethodsWe compiled occurrence data on African ape populations from the IUCN A.P.E.S. database and extracted relevant human-, climate- and habitat-related predictors representing current and future (2050) conditions to predict taxon-specific distribution under a best- and a worst-case scenario, using ensemble forecasting. Given the large effect on model predictions, we further tested algorithm sensitivity by considering default and non-default modelling options. The latter included interactions between predictors and polynomial terms in correlative algorithms. ResultsThe future distributions of gorilla and bonobo populations are likely to be directly determined by climate-related variables. In contrast, future chimpanzee distribution is influenced mostly by anthropogenic variables. Both our modelling approaches produced similar model accuracy, although a slight difference in the magnitude of range change was found for Gorilla beringei beringei, G. gorilla diehli, and Pan troglodytes schweinfurthii. On average, a decline of 50% of the geographic range (non-default; or 55% default) is expected under the best scenario if no dispersal occurs (57% non-default or 58% default in worst scenario). However, new areas of suitable habitat are predicted to become available for most taxa if dispersal occurs (81% or 103% best, 93% or 91% worst, non-default and default, respectively), except for G. b. beringei. Main ConclusionsDespite the uncertainty in predicting the precise proportion of suitable habitat by 2050, both modelling approaches predict large range losses for all African apes. Thus, conservation planners urgently need to integrate land-use planning and simultaneously support conservation and climate change mitigation measures at all decision-making levels both in range countries and abroad.

ecology↗

bioRxiv2019

Novel ankyrin-repeat mutant and modifiers of a kafirin mutant improve sorghum protein digestibility

Sorghum is a staple food for over 500 million people in Sub-Saharan Africa and Asia, however, sorghum proteins are poorly digested when wet-cooked. Three sorghum mutants were identified in a mutagenized population of the inbred line BTx623 that showed a 23-37% increase in wet-cooked protein digestibility compared to their unmutagenized parent. Furthermore, in comparison to the known high lysine, highly digestible sorghum mutant, P721Q, these mutants had 9% more protein overall that was 10% more digestible, had 12% more lysine, as well as better seed hardness. Using bulked segregant analysis based on whole genome sequencing data, we identified unique genomic regions on chromosome 5 of each EMS mutant that are associated with the increase in protein digestibility. Analyzing shared mutations in candidate genes, the high protein digestibility phenotype in one mutant is linked to a point mutation in a novel, ankyrin repeat protein. In another, the increase is associated with a mutation in a kafirin gene and suggests novel genetic modifiers. This study provides material and molecular markers that can be used to enhance sorghum nutritional value, contribute to fighting malnutrition and elucidate new roles for ankyrin-repeat proteins in plants. One sentence summaryMutations in a novel, ankyrin domain protein and genetic modifiers of a known mutation in a seed storage protein lead to increased digestibility of seed proteins in sorghum after wet cooking.

plant biology↗