Climate change likely to extinguish one-third of animal parasites by 2070

Changing climate on the Earth may cause extinction of up to one-third of parasite species by 2070, according to a new study published in the journal Science Advances on September 6. 

The diverse group of organisms or parasites includes tapeworms, roundworms, ticks, lice, fleas and other pests. Parasites have a bad reputation for causing disease in humans, livestock and other animals. But parasites play important roles in ecosystems, and parasite loss could dramatically disrupt ecosystems. 

To find out how climate change is likely to affect the survival of a wide range of parasite species, researchers turned to museum collections. The U.S. National Parasite Collection, containing millions of organisms, provides a broad and deep record of different species' occurrences around the world. Most species are represented by many specimens, meaning researchers can use the museum's records to investigate organisms' geographical distributions and predict changes over time. 

Records from the U.S. National Parasite Collection were combined with additional information from specialized databases cataloging ticks, fleas, feather mites and bee mites to enable a comprehensive global analysis. Then a team including 17 researchers in eight countries spent years tracking down the exact geographical source of tens of thousands of parasite specimens, adding GPS coordinates to their database wherever possible. Using climate forecasts, the researchers compared how 457 parasite species will be impacted by changes in climate under various scenarios. 

The analysis determined that parasites are even more threatened than the animal hosts they rely on. The most catastrophic model predicted that more than a third of parasite species worldwide could be lost by 2070. The most optimistic models predicted a loss of about 10 percent. "(Slowing climate change) has a really profound impact on extinction rates, "said study lead author Colin Carlson, a graduate student in Wayne Getz's laboratory at the University of California, Berkeley. "Parasites are definitely going to face major extinction risk in the next 50 years," Carlson said. "They are certainly as threatened as any other animal group." "climate change has the capacity to alter nearly every dimension of biodiversity," said Nyeema Harris, an assistant professor in the Department of Ecology and Evolutionary Biology of the University of Michigan (UM). 

It is the consensus of the researchers that parasites need to be included in conversations about conservation, given their delicate position in complex ecosystems as the study shows.