Genetic diversity and population structure of the spot-nosed monkey (Cercopithecus petaurista) of the Bijagós Archipelago, Guinea-Bissau, West Africa

Insular populations are typically more vulnerable to the loss of genetic diversity than their mainland counterparts and are often of conservation concern. The Bijagós Archipelago in Guinea-Bissau is a West African biodiversity hotspot and a recently designated UNESCO World Heritage Site. It hosts the westernmost populations of the spot-nosed monkey ( Cercopithecus petaurista ), a species thought to have been extirpated from mainland and threatened by anthropogenic activities. Here, we conducted a non-invasive DNA survey across five of the largest islands with known occurrences. We used eleven microsatellite loci and a fragment of the mitochondrial d-loop to estimate genetic diversity and population structure. Using 64 individual profiles we found that populations may have lost genetic diversity but were not depauperated. Genetic diversity was heterogeneous and populations were structured by island. Higher levels of historical gene flow between distant islands than between nearby ones suggest a pattern that is inconsistent with stepwise colonisation typical of island systems. Our study suggests a complex colonisation history which may have been influenced by human movements in the area. Canhabaque Island holds the most diverse populations and may support reintroductions in the mainland. We suggest conservation management should be carried out by island to safeguard long-term persistence.