Genetic Diversity and Conservation Genetics of Cross River Gorilla Populations in Nigeria

The Cross River gorilla (Gorilla gorilla diehli) is the world's most endangered gorilla subspecies, with a total wild population estimated at fewer than 300 individuals distributed across fragmented forest patches in Nigeria and Cameroon. Nigerian populations are concentrated in Cross River State and Taraba State, within the South South and North East geopolitical zones. Despite the subspecies' critical conservation status, genetic data on Nigerian Cross River gorilla populations remain incomplete, limiting understanding of genetic diversity, population structure, and connectivity. This study employs non-invasive genetic sampling, using fecal DNA, to assess the genetic diversity and population structure of Cross River gorilla groups within the Nigerian range. Samples were collected from eight known gorilla community areas across the Boshi, Kagwene, and Afi Mountain sites. Fourteen microsatellite markers and mitochondrial control region sequences were analyzed. Results indicate lower genetic diversity compared to closely related lowland gorilla subspecies, with significant population subdivision between the Afi Mountain and Boshi-Kagwene site clusters. Evidence of inbreeding is detected in three of the eight sampled groups. Effective population size estimates are alarmingly low, suggesting that the viability window for without intervention is limited. The study recommends urgent forest corridor restoration between isolated population clusters, long-term non-invasive genetic monitoring, and collaboration with Cameroonian counterpart teams for trans-boundary population management. Keywords: Cross River gorilla, conservation genetics, genetic diversity, South South Nigeria, endangered primates