Primate hotspots on Borneo: Predictive value for general biodiversity and the effects of taxonomy

The identification of hotspots, or geographic areas that are particularly rich in biodiversity, is increasingly used to set conservation priorities. We investigated the spatial patterns of primate species richness and endemism in Borneo to assess whether primates are good indicators of biodiversity hotspots for other taxa. Based on locality records for the 13 primate species present on the island (n=1414, range 26-273 records/species), we prepared primate distribution maps. By overlaying these distribution maps in a geographic information system, we created maps that revealed the most species-rich area to be a tropical wet evergreen forest in central-eastern East Kalimantan, Indonesia, in which 11 species coexisted. No other studies had so far identified this region as a biodiversity hotspot. Generally, the Malaysian states of Sabah and Sarawak are considered richest in general species diversity. We suggest that the main reason for this is the low number of biodiversity studies that have been conducted in Indonesian Borneo compared with Malaysian Borneo and a focus in biodiversity studies on mountain habitats rather than lowlands. We used two alternative taxonomic classifications of Bornean primates, one based on a biological and the other on a phylogenetic species concept, to determine whether the outcome of hotspot identification depended on taxonomic classification. The location of endemic primate species hotspots depended on the choice of species concept, whereas identification of the hotspots of primate species richness was not affected by choice of species concept. Our results suggest that a hotspot identification based on a relatively small group of taxa can vary with the group of species under investigation and their taxonomic classifications. Because of the lack of congruence between fine-scale hotspots of Bornean primate diversity and other hotspots reported in the literature, Bornean primates appear unsuitable for identifying areas of general species richness. Bornean primates may, however, be useful indicators of lowland diversity on the island.