Mutualisms in a warming world—how increased temperatures affect the outcomes of multi-mutualist interactions

In nature, plant species simultaneously interact with many different mutualistic partners. These mutualists may influence one another through direct interference or indirectly by competing for shared reward resources or through alteration of plant traits. Together, these mutualists also may combine to affect plant hosts in ways that may not be predictable based on pairwise interactions. Given that the outcome of mutualistic interactions often depends on environmental conditions, multi-mutualist effects on one another and their plant hosts may be affected by global changes. Here, we grew focal plants under simulated global warming conditions and manipulated the presence of partner mutualists to test how warming affects the outcome of interactions between focal plants and their partners (nitrogen-fixing rhizobia, ant defenders, and pollinators) and interactions among these partner mutualists. We find that warming alters the fitness benefits plants receive from rhizobium resource mutualist..., ,