Contribution of DNA-typing to bushmeat surveys: assessment of a roadside market in south-western Nigeria

Abstract

Context Following recent socioeconomic transformations in western and central Africa, the volume of bushmeat hunting, a traditional source of proteins and revenue for rural populations, has reached unsustainable levels. The morphological identification of species sold on bushmeat market stalls may be challenging because of the presence of cryptic taxa and smoked or processed carcasses. Aims To assess the contribution of DNA-typing to traditional bushmeat surveys. We conducted a case study at a roadside bushmeat market in Asejire, south-western Nigeria, to characterise the mammalian diversity and sketch out the dynamics of the bushmeat trade. Methods We generated a 402-bp Cytochrome b fragment using a ‘universal’ mitochondrial primer pair that successfully amplified across five mammalian orders, and used assignment procedures to assess the taxonomic identification of the traded species. We combined DNA-typing with morphological-based market surveys and questionnaires to half (n = 20) of the market stakeholders. Key results Our combined morphological–DNA-based survey revealed a total of 17 species, representing seven mammalian orders (Rodentia, Lagomorpha, Primates, Hyracoidea, Carnivora, Pholidota and Artiodactyla). DNA-typing allowed identifying the Walter’s duiker, a cryptic, newly described species from the Dahomey Gap, and diagnosing an unidentified primate as the white-throated monkey, Cercopithecus erythrogaster, a species of high conservation concern in Nigeria. K2P pairwise genetic distances among all species exceeded the 11% threshold, indicative of species-level distinction. The most hunted species were the Walter’s duiker and, to a lesser extent, the greater cane rat, Thryonomys swinderianus. Questionnaires to traders revealed that the Asejire roadside market was a straightforward trader–hunter system centralising off-takes from distant hunting sites. Conclusions We showed how mitochondrial DNA-typing combined with assignment procedures improved the characterisation of the mammalian diversity sold on bushmeat markets. The hunted mammalian community consisted of versatile, small- to medium-sized secondary forest species characteristic of the Dahomey Gap assemblage; their sustainable management is in doubt because of the lack of conservation and health awareness within the traders’ community. Implications Given the utility of mitochondrial DNA-typing in identifying species sold in bushmeat markets, we argue in favour of multi-entry investigations to reach a comprehensive characterisation of the bushmeat trade. The building of a web-accessible mtDNA database covering the spectrum of the species hunted for bushmeat would appear to be a valuable diagnostic tool that may help Nigeria and neighbouring countries to set up a rigorous monitoring of wildlife extirpation.