Water limitation reveals local adaptation and plasticity in the drought tolerance strategies of <i>Bouteloua gracilis</i>

As the frequency and severity of drought increase in many regions around globe, quantification key tolerance traits intraspecific variability these will improve predictions vulnerability a species to novel conditions. The objective this study was quantify correlate sensitivity plant growth different soil moisture levels across populations Bouteloua gracilis. Fourteen B. gracilis were sampled along one local elevation-aridity gradient northern Colorado latitude-aridity from South Dakota New Mexico. Individuals each population clonally propagated subjected high low treatments greenhouse measured for gas exchange, midday water potential (Ψmid), osmotic (Ψosm), biomass production, morphological traits. Under water-abundant conditions, plants most arid region produced more total (67%) than mesic system, yet experienced greatest (−34%) when limitation. Productivity strongly negatively correlated with magnitude investment all populations: megapascal decrease 2.3 g under water-limited Gas-exchange leaf measurements did not explain patterns. Unlike regions, adjust Ψosm. This lack plasticity may be adaptation likely source increased populations.