The partitioning of Africa: statistically defined biogeographical regions in sub‐Saharan Africa
Aim To test whether it is possible to establish a common biogeographical regionalization for plants and vertebrates in sub‐Saharan Africa (the Afrotropical Region), using objective multivariate methods.
Location Sub‐Saharan Africa (Afrotropical Region).
Methods We used 1° grid cell resolution databases for birds, mammals, amphibians and snakes (4142 vertebrate species) and c. 13% of the plants (5881 species) from the Afrotropical Region. These databases were analysed using cluster analysis techniques to define biogeographical regions. A β(sim) dissimilarity matrix was subjected to a hierarchical classification using the unweighted pair‐group method with arithmetic averages (UPGMA). The five group‐specific biogeographical regionalizations were compared against a regionalization developed from a combined database, and a regionalization that is maximally congruent with the five group‐specific datasets was determined using a consensus classification. The regionalizations were interpreted against measures of spatial turnover in richness and composition for the five datasets as well as the combined dataset.
Results We demonstrate the existence of seven well‐defined and consistent biogeographical regions in sub‐Saharan Africa. These regionalizations are statistically defined and robust between groups, with minor taxon‐specific biogeographical variation. The proposed biogeographical regions are: Congolian, Zambezian, Southern African, Sudanian, Somalian, Ethiopian and Saharan. East Africa, the West African coast, and the transitions between the Congolian, Sudanian and Zambezian regions are unassigned. The Cape area in South Africa, Afromontane areas and the coastal region of East Africa do not emerge as distinct regions but are characterized by high neighbourhood heterogeneity, rapid turnover of species and high levels of narrow endemism.
Main conclusions Species distribution data and modern cluster analysis techniques can be used to define biogeographical regions in Africa that reflect the patterns found in both vertebrates and plants. The consensus of the regionalizations between different taxonomic groups is high. These regions are broadly similar to those proposed using expert opinion approaches. Some previously proposed transitional zones are not recognized in this classification.
Document Type: Research Article
Affiliations: 1: Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH 8008 Zurich, Switzerland 2: Department of Geography and Environmental Studies, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa 3: Institute of Systematic Botany, Zollikerstrasse 107, CH 8008 Zurich, Switzerland 4: Center for Macroecology, Evolution and Climate at Zoological Museum, Natural History Museums of Denmark, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark 5: Center for Macroecology, Evolution and Climate and Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark
Publication date: 2012-07-01