Plant Adaptation in Variable Environments

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

All organisms face uncertainty in their environment, yet their strategies for managing that uncertainty are diverse: some avoid it by only using a narrow range of habitats or resources, while others tolerate it by being flexible and adjusting as conditions change. Understanding how these different strategies arise, and the circumstances that favor one strategy over another, is critical to explain why species live where they do, and how they will respond to future environmental change. In this project, the researchers are studying how plants respond to uncertainty in the amount of water they experience by conducting controlled experiments with plants that occupy seasonally-flooded wetlands in western North America. These plants occupy different habitats within the wetlands - ranging from the deepest to the shallowest positions - and thus are expected to show a range of responses to different water conditions. By evaluating how these plants adjust to uncertainty in soil moisture and flooding, the scientists will gain a general understanding of the different ways that organisms handle changes in their environments. This knowledge is broadly significant for predicting how organisms will respond to future environmental uncertainty, including climate change, habitat loss, and biological invasions. In addition, these results will directly affect the management of plants and animals that occupy wetlands, and the results of this work will be directly communicated to practitioners involved in the conservation and restoration of wetland ecosystems. In these experiments, the investigators manipulate the overall levels of water availability (ranging from drought to flooding), as well as the extent of variability in soil moisture and flooding, in a series of controlled experiments in a growth chamber environment. The study organisms are three annual species of Lasthenia (Asteraceae) that are adapted to different hydrological environments within vernal pool wetlands in California. The researchers will measure the survival and reproductive output of these three species under the different water treatments, while also measuring changes in leaves and root architecture to quantify plant phenotypic responses to fluctuating hydrological conditions. These data will be used to test the hypothesis that phenotypic flexibility (i.e., plasticity in leaf and root traits) will be important for predicting plant performance when water levels fluctuate, but that this plasticity may reduce performance when water levels are constant. We also predict that the three species will exhibit unique responses to the water treatments that reflect adaptations to their respective microhabitats.