Genetic consequences of human forest exploitation in two colobus monkeys in Guinea Bissau

Abstract

The ability of forest-dwelling species to adapt to changes in their habitat is being increasingly challenged by the rapid pace of human-induced forest degradation. Understanding the effect of such environmental changes on biodiversity requires comparative analyses across species living within the same habitats. We investigated the effect of forest exploitation on the genetic structure and demography of two sympatric arboreal primates showing differences in their socioecology: the Western black-and-white colobus (Colobus polykomos) and Temminck's red colobus (Procolobus badius temminckii). We conducted the study in a fragmented and human-impacted forest in Guinea Bissau. Using microsatellite data from six C. polykomos and eight P. b. temminckii social groups, we found that in C. polykomos the distribution of genetic diversity followed an isolation-by-distance pattern whereas for P. b. temminckii, the results suggested restriction in female dispersal. We detected a strong, recent bottleneck for both primates, which we inferred to have resulted from the anthropogenic exploitation of forest resources in the last centuries. The bottleneck signal was stronger for P. b. temminckii as a likely consequence of its larger estimated ancestral population size. Finally, we discussed the different analytical approaches used. Our results confirm that P. b. temminckii is more affected by habitat changes than C. polykomos, despite being phylogenetically close. Nonetheless, the low estimated effective population sizes and the known demographic changes indicate that both species are severely threatened by human forest exploitation, requiring urgent conservation action.