Protecting biodiversity is more than an act of environmental preservation; it can be a matter of self-preservation, according to a study that shows healthy biodiversity in intact ecosystems helps ward off infectious disease.

“As buffering species disappear, rates of disease spread can accelerate,” says Drew Harvell, professor of Ecology and Evolutionary Biology at Cornell University and a co-author of the study, “Impacts of Biodiversity on the Emergence and Transmission of Infectious Diseases,” which is published online in the current issue of Nature. Felicia Keesing, of Bard College, is the paper’s lead author.

“More broadly, biodiversity per se seems to protect organisms, including humans, from transmission of infectious diseases in many cases,” the authors note. “Preserving biodiversity in these cases, and perhaps generally, may reduce the incidence of established pathogens.”

The authors argue that, in a diverse ecosystem, often only a fraction of organisms are susceptible to particular diseases or parasites – the presence of buffering species means the spread of a malady is muted. One example is Lyme Disease, which can be transmitted to humans by ticks carried by white-footed mice. In intact communities with opossums, the ticks attack opossums, but they fail to survive on opossums, thus reducing the transmission rate of Lyme Disease.

“This discovery of the buffering effect is most clear on land where we know all the links in the transmission of some diseases. In the oceans, we are dealing with a vast new equation relating to disease spread, climate change and biodiversity,” Harvell said. “Disease outbreaks are being accelerated by climate warming before we even know the links in the disease transmission chain.”

The report recommends stringent oversight of farming animals on land and fishes in the oceans to limit the chances of diseases spreading from farmed animals to people or wildlife.