Climate change, land-use change and the fungal disease chytridiomycosis.

Those are the main causes why more than 30 per cent of all amphibian species have appeared on the Red List of the International Union for the Conservation of Nature (IUCN).

With so many threatened species in their ranks, amphibians are much further along the way to extinction than any other animal group. And to make matters worse, a new study in Nature now shows that areas with the highest amphibian diversity are actually most likely to suffer from one of the three major threats.

Overlapping threats

An international team of researchers found as much as two thirds of the global amphibian diversity hotspots will be heavily disturbed by at least one of the three threats. In fact climate and land-use change tend to often affect the same areas, making the threat to amphibian species richness twice as great.

Climate change in itself is predicted to have its largest effect on the amphibian fauna in Africa, parts of Northern South America and the Andes. The fungal disease chytridiomycosis on the other hand shows little regional overlap with the other two threats and seems to do its devastating work on its own, especially in the Americas and Australia.

From predator to prey

On the basis of the perceived risk factors working in unison, the research team fears that previous risk assessments based on just one threat might be too optimistic. They consider it likely that amphibian declines will accelerate this century.

Amphibians arose in the Devonian and have been around for a few hundred million years. They have survived the coming of the reptiles during the Triassic, changing them from large top predators to the (mostly) small animals we see today.

But will they also survive the coming of man? Or will the rapid onslaught of the Holocene Extinction finally be the end of them? What these new findings highlight is that greater conservation efforts are needed to keep amphibians around for a while longer.

© Jorn van Dooren | www.bitsofscience.org