Species Interactions Could Be Affected By Global Warming
June 23, 2012

Species Interactions Could Be Affected By Global Warming

Yale and University of Connecticut researchers report that more extinctions will take place due to global warming should "scientists fail to account for interactions among species in their models."

According to Phoebe Zarnetske, primary author and postdoctoral fellow at Yale´s School of forestry & Environmental Studies department, “Currently, most models predicting the effects of climate change treat species separately and focus only on climatic and environmental drivers." She goes on to state, "But we know that species don't exist in a vacuum. They interact with each other in ways that deeply affect their viability."

The intricacy of “species interaction networks” does not promote models that tell what effect climate change has on these predators, according to Zarnetske. She goes on to say that, by the year 2050, somewhere from 15 to 37 percent of these animals will be facing extinction.

What is the effect of other species in the food chain? Researchers indicate that predators and herbivores are strongly connected to many other animals. Researchers indicate that these species are “biotic multipliers” which increase extinction risk and change the ranges of many animals below predators in the food chain.

"Climate change is likely to have strong effects on top consumers. As a result, these effects can ripple through an entire food web, multiplying extinction risks along the way," said Dave Skelly, a co-author of the study and professor of ecology at Yale.

The paper, "Biotic Multipliers of Climate Change Effects," indicates that by focusing on the biotic multipliers along with their interactions with species, it is a promising way to improve what predictions of the effects of climate change have on the predators.

On Isle Royale, an island in Lake Superior, rising winter temperatures and a disease outbreak caused wolf populations to decline and the number of moose to surge, leading to a decline in balsam fir trees. Elevated temperatures in the rocky intertidal of the North American Pacific Coast indicate that without predators, the result is lower diversity among lower species. And in Arctic Greenland, research shows that without caribou and muskoxen as top herbivores, elevated temperatures can lead to less diversity in tundra plants and, in turn, affect many other species dependent on them.

"Species interactions are necessary for life on Earth. We rely on fisheries, timber, agriculture, medicine and a variety of other ecosystem services that result from intact species interactions," said Zarnetske. "Humans have already altered these important species interactions, and climate change is predicted to alter them further. Incorporating these interactions into models is crucial to informed management decisions that protect biodiversity and the services it provides."

Models with species interactions, according to the paper, would enable tracking of the biotic multipliers by following how changes in the abundance of species studied, such as top consumers; change the composition of communities of species. But more studies need to be done.

"Collecting this type of high-resolution biodiversity data will not be easy. However, insights from such data could provide us with the ability to predict and thus avoid some of the negative effects of climate change on biodiversity," said Mark Urban, a co-author and an assistant professor in the Department of Ecology and Evolutionary Biology at the University of Connecticut.