Tuesday, August 3, 2010 - 2:55 PM

SYMP 7-5: Do species interactions matter? Realized responses to climate change

Mark C. Urban, University of Connecticut and Sarah A. Gilman, The Claremont Colleges.


Species are predicted to shift geographic range shifts under climate change.  To date, most research has centered on understanding how climate change will shape new ranges by altering abiotic components of the fundamental niche.  Yet, species interactions also shape range boundaries, both by altering the realized niche and by influencing a species' tolerance of climate.  Climate change thus can affect biotic range limits directly or indirectly through modifying the strength or direction of species interactions (e.g., temperature-dependent competition) and by altering range overlaps among interacting species. This last effect occurs if each species in a community tracks climate changes differently. Changing range boundaries can lead to novel ‘no-analogue’ communities and potentially break apart obligate relationships among coevolved organisms.  Here, we assess evidence for how important species interactions might be for predicting future range shifts and outline ways to incorporate species interactions into predictive models. 


We suggest using community ‘modules’ to organize ideas about how climate change and dispersal variation will affect community interactions in communities and resultant patterns of species composition along geographic clines.  Through this approach, we identify three critical elements of community interactions that will determine impacts of climate change.  First, obligate interactions such as specialist mutualists and predators will be subject to stronger impacts from climate change.  Second, a greater variance in dispersal abilities among interacting species will lead to more broken linkages and novel interactions.  Third, the specific structure of food webs and position of species in this structure will critically control the degree to which species risk extinction  through direct and indirect effects. For instance, less diverse and longer food webs should be more susceptible to climatic alterations.  Ultimately, accurate predictions for patterns of biological diversity under warmer conditions will require a more sophisticated understanding of the realized niche and food web interactions in theoretical and empirical research.