Genetic signatures of a demographic collapse in a large-bodied forest dwelling primate (Mandrillus leucophaeus)


Nelson Ting, Department of Anthropology, University of Oregon, 308 Condon Hall, Eugene, OR 97403. Tel: 541-346-5509; Fax: 541-346-0668; E-mail:
Funded by the University of Iowa and the German Primate Center. Sample collection was also funded by the Offield Family Foundation, the Margot Marsh Biodiversity Foundation, the USFWS Great Ape Conservation Fund, the CTFS of the Smithsonian Institute, the WCS Fellowship Fund, the Arcus Foundation, the Exxon Mobil Foundation, Drexel University, and the LA Zoo.

These authors contributed equally to this work.


It is difficult to predict how current climate change will affect wildlife species adapted to a tropical rainforest environment. Understanding how population dynamics fluctuated in such species throughout periods of past climatic change can provide insight into this issue. The drill (Mandrillus leucophaeus) is a large-bodied rainforest adapted mammal found in West Central Africa. In the middle of this endangered monkey's geographic range is Lake Barombi Mbo, which has a well-documented palynological record of environmental change that dates to the Late Pleistocene. We used a Bayesian coalescent-based framework to analyze 2,076 base pairs of mitochondrial DNA across wild drill populations to infer past changes in female effective population size since the Late Pleistocene. Our results suggest that the drill underwent a nearly 15-fold demographic collapse in female effective population size that was most prominent during the Mid Holocene (approximately 3-5 Ka). This time period coincides with a period of increased dryness and seasonality across Africa and a dramatic reduction in forest coverage at Lake Barombi Mbo. We believe that these changes in climate and forest coverage were the driving forces behind the drill population decline. Furthermore, the warm temperatures and increased aridity of the Mid Holocene are potentially analogous to current and future conditions faced by many tropical rainforest communities. In order to prevent future declines in population size in rainforest-adapted species such as the drill, large tracts of forest should be protected to both preserve habitat and prevent forest loss through aridification.