Additive threats from pathogens, climate and land-use change for global amphibian diversity

Amphibian populations are declining; here, the spatial distribution and interactions of threats from climate change, land-use change and the spread of fungal disease are assessed. Triple hazard for amphibians Amphibians are the most threatened vertebrate class, and the three most serious concerns are climate change, land-use change and the fungal disease chytridiomycosis. An analysis of the interaction of these threats for an almost complete set of amphibian species reveals considerable overlap between the regions at risk from climate change and land-use change. Fungal disease is generally found in different areas, contradicting previous studies linking climate change to disease threats in tropical regions. But worryingly, the areas of greatest species richness are the areas subject to the highest threat. Amphibian population declines far exceed those of other vertebrate groups, with 30% of all species listed as threatened by the International Union for Conservation of Nature 1 , 2 , 3 . The causes of these declines are a matter of continued research, but probably include climate change, land-use change and spread of the pathogenic fungal disease chytridiomycosis 1 , 4 , 5 . Here we assess the spatial distribution and interactions of these primary threats in relation to the global distribution of amphibian species. We show that the greatest proportions of species negatively affected by climate change are projected to be found in Africa, parts of northern South America and the Andes. Regions with the highest projected impact of land-use and climate change coincide, but there is little spatial overlap with regions highly threatened by the fungal disease. Overall, the areas harbouring the richest amphibian faunas are disproportionately more affected by one or multiple threat factors than areas with low richness. Amphibian declines are likely to accelerate in the twenty-first century, because multiple drivers of extinction could jeopardize their populations more than previous, mono-causal, assessments have suggested.