The Earth's surface has warmed by approximately 0.6C over the past century, and is expected to experience a further warming of 1.4 to 5.8C over the next century. A central challenge to predicting how species will fare in a warmer climate is to understand how the responses of organisms to climate change are likely to affect their interactions with other species, which will ultimately determine their presence or absence in the future. In order to accomplish this task, we will study the mechanisms by which climate change alters species interactions in two well-studied systems: gray wolf food webs in Yellowstone National Park and Isle Royale National Park. The reintroduction of gray wolves to Yellowstone National Park in 1995 provides a research opportunity for comparing the functioning of an ecosystem with and without a keystone top predator under different climate change scenarios. Long-term data from Isle Royale, on changes in the numbers of wolves and moose, and on changes in growth of balsam fir, allow for a unique analysis of community response to climate change. This research will contribute to both ecological theory, by providing insight into the consequences of rapid climate change for species interactions, and to applied ecology and management, by generating predictions about the potential consequences of climate change for wolf-mediated systems in two National Parks.
