Rivers as Barriers to Primate Distributions in Africa

• Published in: International journal of primatology 2012-02, Vol.33 (1), p.168-183
• Main Authors: Harcourt, A. H., Wood, M. A.
• Format: Article
• Language: English
• Subjects: Africa; Animal Ecology; Animal Genetics and Genomics; Animal populations; Anthropology; Biogeography; Biomedical and Life Sciences; Body image; Body size; Central Africa; Evolutionary Biology; Geographic distribution; Geographical distribution; Geography; Human Genetics; Life Sciences; Primates; Primatology; Rivers; Statistical analysis; Taxa; Taxonomy; West Africa; Zoology
• ISSN: 0164-0291; 1573-8604
• DOI: 10.1007/s10764-011-9558-z

Rivers border the geographic distributions of primate taxa, but the extent to which the rivers are effective barriers is debated. We here provide the first statistically substantiated analysis of the role of rivers as barriers to the distribution of primates in west and central Africa, as judged by the coincidence of the edge of distributions of forest-dwelling primates with rivers. We use data from the literature to analyze the distributions of 14 genera, 44 species, and 77 subspecies around 18 rivers, river groups, or stretches of rivers. Rivers bordered the distributions of more new taxa (subspecies) than of old taxa (genera), although within genera, age of origin of the taxon did not correlate with likelihood of rivers bordering distributions. Fewer taxa crossed wide rivers than crossed narrow ones. Some analyses indicated that more smaller-bodied genera were stopped by smaller rivers than were larger-bodied genera, but other analyses indicated no effect of body size. Genera with smaller geographic ranges crossed a smaller proportion of the rivers that they met than did genera with large ranges, implying a fundamental difference between small- and large-range taxa in their ability to disperse. Specialization might be the operating trait. Finally, although the aridity of the biogeographic gap in west Africa, the Dahomey Gap, is often argued to be the barrier to movement of species across the Gap, we found that for half the primate species that do not cross the Gap, the rivers that border the Gap could in fact be the effective barrier.