New Haven, Conn.Global warming may cause more extinctions than predicted if scientists fail to account for interactions among species in their models, Yale and UConn researchers argue in Science.
"Currently, most models predicting the effects of climate change treat species separately and focus only on climatic and environmental drivers," said Phoebe Zarnetske, the study's primary author and a postdoctoral fellow at the Yale School of Forestry & Environmental Studies. "But we know that species don't exist in a vacuum. They interact with each other in ways that deeply affect their viability."
Zarnetske said the complexity of "species interaction networks" discourages their inclusion in models predicting the effects of climate change. Using the single-species, or "climate envelope," approach, researchers have predicted that 15 percent to 37 percent of species will be faced with extinction by 2050.
But research has shown that top consumerspredators and herbivoreshave an especially strong effect on many other species. In a warming world, these species are "biotic multipliers," increasing the extinction risk and altering the ranges of many other species in the food web.
"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 argues that focusing on these biotic multipliers and their interactions with other species is a promising way to improve predictions of the effects of climate change, and recent studies support this idea. 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. Studies in the rocky intertidal of the North American Pacific Coast show
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