Meeting Abstract
Evidence for the relative importance of direct effects of climate change and indirect effects mediated thorough species interactions is limited. Among these limited studies, there is contrasting support for stronger direct versus indirect effects of changes in climate on communities. Trait-based approaches aimed at explaining such variation in responses to climate change have met with considerable success. The question then is whether we can use trait-based approaches to predict when direct effects of temperature rise or indirect effects of altered species interactions are likely to dominate responses to climate change. Thermal tolerance traits might inform when species interactions are likely to be important, as only subsets of communities will be able to use the available warmer climatic niches and competition intensifies in the remaining cooler climatic niches. Here we explore the relative roles of the direct effects of temperature change and indirect effects of species interactions on forest ant communities warmed as part of a large scale climate manipulation at high and low latitude sites in eastern North America. We found overall mixed support for the importance of species interactions, but found that the magnitude of these interaction effects was predictable based on the upper thermal tolerance of the focal species. Forager abundance and nest site occupancy of heat intolerant species was more often influenced by interactions with other species than by direct effects of temperature. Our findings suggest that thermal tolerance may be used as a general guide for when species interactions will be more likely to influence responses to global climate change.
