The latest Red List of the International Union for Conservation of Nature (IUCN) reveals that myriad factors are wreaking havoc on amphibian populations around the globe. Their numbers are dwindling faster than those of other animal groups, with over 30% of all amphibian species listed as 'threatened'. The study, presented in the journal Nature, underlines that areas containing the greatest number of amphibian species are the areas that are at most risk. Led by the University of Copenhagen in Denmark, the study brought together experts from Denmark, Portugal, Spain and the United States.
Professor Carsten Rahbek from the Center for Macroecology, Evolution and Climate (CMEC) at the University of Copenhagen and his team identified various factors that put global amphibian diversity at risk, but noted that the spatial distribution of these threats and interactions are poorly known. Climate change, land use change and the fungal disease chytridiomycosis are some of the serious threats that the amphibian species face.
The researchers postulate that the greatest proportions of species adversely affected by climate change, what is probably the most serious threat, will be in Africa, parts of northern South America and the Andes. Their data also suggest that amphibian declines will probably accelerate in the 21st century, due to the multiple drivers of extinction that could threaten their populations more than previous, monocausal assessments have reported.
Lead author Christian Hof of the CMEC, also from the Department of Biodiversity and Evolutionary Biology at the National Museum of Natural Sciences in Spain, and colleagues evaluated the geographical distribution of these threats in relation to the global distribution of amphibians.
'Regions where climate and land-use change have the highest projected impact on amphibians tend to overlap,' explains Dr Hof. 'By contrast, the threat posed by the fungal disease shows little spatial overlap with the other two threats.'
The chance for the majority of species-rich areas across the globe to be exposed to at least one, if not more threats, than areas with low species richness is greater, according to the researchers.
'Our study shows that more than two thirds of the global amphibian diversity hotspots will likely be strongly affected by at least one of the three threats considered,' says Miguel Araújo from the Spanish Research Council (CSIC), one of the authors of the study.
With respect to the observed overlapping of risk factors, the team suggests that risk assessments based on a single threat will probably be over-optimistic.
'Our assessment shows that amphibian declines are likely to accelerate over the next decades, as multiple drivers of extinction could jeopardise their populations more than previous, monocausal, assessments have suggested,' explains Professor Rahbek.
Commenting on the findings of the study, co-author Walter Jetz of Yale University says: 'With more than 30% of all amphibian species already listed as threatened by IUCN and many rare species still being discovered every year, our results highlight the need for greater conservation research and action for this highly threatened group.'