TY - JOUR T1 - Extending the Stress-Gradient hypothesis: increased local adaptation between teosinte and soil biota at the stressful end of a climate gradient JF - bioRxiv DO - 10.1101/031195 SP - 031195 AU - Anna M. O’Brien AU - Ruairidh J.H. Sawers AU - Jeffrey Ross-Ibarra AU - Sharon Y. Strauss Y1 - 2015/01/01 UR - http://biorxiv.org/content/early/2015/11/11/031195.abstract N2 - In order to predict plant responses to rapid climate change, we will need to understand the role of biotic interactions in plant climate adaptation. We extend the stress-gradient (SG) hypothesis to posit that, as interactions become more mutualistic at stressful ends of environmental gradients, so does selection for mutualistic co-adaptation. We call this the stress-gradient evolution hypothesis (SGE). We test our SGE hypothesis in the interactions of teosinte (Zea mays ssp. mexicana) with its rhizosphere soil biota in populations across a climate gradient. In support of SGE predictions, we find local adaptation of teosinte to soil biota at the stressful (cold) end of our climatic gradient but not at the benign (warm) end: sympatric combinations of plants and biota from stressful sites both increase plant fitness and generate more locally adapted plant phenotypes. Our results suggest that co-adaptation of interacting partners may be a means of ameliorating stressful environments. ER -