Modelling the spatial baseline for amphibian conservation in West Africa

Abstract

To answer questions such as whether the existing network of protected areas is sufficient, conservation needs data covering complete taxonomic groups and large geographic areas. However, most distributional data sets are either coarse, patchy and/or based solely on expert opinion which is often hard to verify. In addition, not all regions are equally well studied. For example sub-Saharan Africa remains comparatively under-sampled for most taxa, especially Central and Western Africa. However, these regions contain many threatened species, including a high diversity of highly threatened vertebrates - amphibians. To fill this knowledge gap, we extrapolated species occurrence records (n = 15,944) on a 30 arc-seconds grid for most known West African amphibian taxa (92%), using environmental niche modelling and employing relevant environmental parameters (climate, vegetation, elevation & distance to rivers).We provide, for the first time, a fine scale distribution map of amphibian alpha diversity for the entire West African region. Already known centres of high biodiversity were confirmed (e.g. south-western Ghana and south-eastern Côte d’Ivoire) and new ones were identified (e.g. northern Liberia and the borders of Liberia with Guinea and Sierra Leone). Diversity analyses focusing on unique amphibians, i.e. threatened, endemic and evolutionary distinct species', revealed that areas of high diversity also contained many high conservation-priority species. Herewith, we offer a comprehensive baseline for identifying those areas which are important for amphibian conservation for one of the most periled regions on the continent. Those areas of high diversity were only partly in accordance with previous analyses such as the hotspot definitions, the ecoregion analyses, or analyses of other taxa, highlighting the added new value of our approach. The most outstanding areas of amphibian diversity were only partly covered by the existing network of protected areas. Thus there is an urgent need to devise a regional conservation concept to protect West African amphibians from extinction.