Species interactions change in outcome across environmental gradients. Below, a photo shows some high alpine plants growing in close proximity. At such high elevation sites, these plants may mutually ameliorate stressful aspects of the environment (cold, unstable soil, drying winds), whereas at lower elevations, the same species are more likely to compete strongly for resources. Similar changes in interactions occur for many types of species interactions, and may have wide-ranging evolutionary consequences, such as increasing mutualism and local adaptation in stressful environments. Together with my co-authors, I explore these ideas and a testing framework in a forthcoming paper at AmNat. Check out the summary available from the journal.