9623772 Gross Environments differ in both the level and spatial scale of heterogeneity in resources. Plants can respond to this variation either by individually buffering environmental changes without decreasing their reproductive success or by avoiding exposure to the negative portion of environmental variation through seed dispersal. If an individual cannot buffer or avoid deleterious environmental change then its performance will decline. Research funded by this award will address whether genetic variation exists within plant populations for either buffering capacity or avoidance of environmental heterogeneity. The native grass, Danthonia spicata, will be used as a model system. Field experiments will assess the magnitude and scale of environmental variation experienced by several grass genotypes and a greenhouse study will test whether the same genotypes vary in their ability to buffer variation in one key growth resource, soil nitrogen. Fitness consequences of differences among individuals in buffering capacity will be tested. Understanding the ability of species to respond to environmental variation through joint response of multiple traits should be helpful in predicting how native plant populations will cope with environmental degradation.
