Species-rich amphibian communities better able to fend off parasitic infections

By Puneet Kollipara

Web edition: February 13, 2013
Print edition: March 23, 2013; Vol.183 #6 (p. 8)

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DIVERSITY AND DISEASE

In a study involving a parasitic flatworm that causes limb deformities in frogs (shown), researchers show why many ecological communities with greater species diversity are better at controlling infectious disease.

Credit: D. Herasimtschuk, Freshwaters Illustrated

In the frog pond, more species means better health for all. More diverse amphibian communities are less likely to transmit a virulent parasite that causes limb deformities in frogs, researchers report in the Feb. 14 Nature.

Pieter Johnson of the University of Colorado Boulder and colleagues used field data from hundreds of California ponds to show that susceptible species dominate in less diverse amphibian communities. In communities that are more diverse, more resistant species move in.

Communities with high species diversity had nearly 80 percent less transmission of the trematode parasite Ribeiroia ondatrae, and suffered roughly half as much disease as communities with low diversity. And in lab and experimental pond studies, transmission and disease rates decreased after researchers added more species.

The work showed that it’s not just the total diversity that matters — newcomers tend to be less susceptible to disease, helping the whole community cut the parasite’s transmission. That finding may help explain why many wildlife communities with greater biodiversity are better at controlling infectious disease. As a result, preserving biodiversity could serve as a tool to help manage the spread of disease, the researchers conclude.

Still, that recommendation may not always hold. In those wildlife communities where newcomer species may be more susceptible, greater biodiversity could actually boost disease transmission.