Meeting Abstract

113-3   14:00 - 14:15  Drought stress alters functional trait dynamics but does not increase performance tradeoffs in a plant species Steven, JC*; Ransone, KE; Collar, DC; Christopher Newport University janet.steven@cnu.edu

Performance is central to our understanding of the fit between morphology and the environment. Morphology limits an organism’s performance capacities, while performance determines fitness within particular environmental circumstances. In addition, the inability to simultaneously maximize multiple performance dimensions can lead to tradeoffs that impose fundamental constraints. Tradeoffs may not be static, however, and relationships between performance traits and the morphological and physiological components that determine them may vary across environments. In plants, modular and indeterminate growth combined with plasticity in organ size and resource allocation may enable a dynamic functional response to stressful environments. To test this, we grew Silene latifolia plants under a control treatment with adequate water and a drought treatment with restricted water. We measured two performance traits, flower production and total plant biomass, and two functional traits, flower mass and specific leaf area (a leaf trait related to physiology). In both drought and control conditions, both sexes showed a tradeoff between performance traits, and larger plants made fewer flowers per gram of biomass. However, plants showed considerable plasticity in response to water stress; plants in the drought treatment made smaller flowers and smaller leaves and had less biomass overall. In the control treatment, flower mass affected performance more strongly than specific leaf area, while in the drought treatment specific leaf area was more strongly related to performance traits. Our results indicate that water stress does in fact alter functional relationships, and contrary to the expectation that stressful conditions exacerbate tradeoffs, we find that water stress leads to somewhat weaker tradeoffs.