Plant Adaptation in Variable Environments

所有生物都面临着环境的不确定性，但它们管理这种不确定性的策略却各不相同：有些生物通过只使用有限的栖息地或资源来避免这种不确定性，而另一些生物则通过灵活性和随着条件的变化而调整来容忍这种不确定性。了解这些不同的策略是如何产生的，以及有利于一种策略而不是另一种策略的环境，对于解释物种为什么生活在它们所生活的地方，以及它们将如何应对未来的环境变化至关重要。在这个项目中，研究人员正在研究植物如何对它们所经历的水量的不确定性做出反应，方法是对北美西部季节性淹没湿地的植物进行受控实验。这些植物在湿地内占据不同的生境-从最深的位置到最浅的位置-因此预计会对不同的水条件表现出一系列的反应。通过评估这些植物如何适应土壤湿度和洪水的不确定性，科学家们将对生物体处理环境变化的不同方式有一个大致的了解。这些知识对于预测生物如何应对未来的环境不确定性，包括气候变化，栖息地丧失和生物入侵具有广泛的意义。此外，这些结果将直接影响对占据湿地的动植物的管理，这项工作的结果将直接传达给参与湿地生态系统保护和恢复的从业人员。在这些实验中，调查人员操纵了水资源的总体可用水平（范围从干旱到洪水），以及土壤水分和洪水的变化程度，在一系列受控实验中，在生长室环境。研究生物是三个一年生种的Lasthenia（菊科），是适应不同的水文环境内春池湿地在加州。研究人员将测量这三个物种在不同水处理下的生存和繁殖产量，同时还测量叶片和根系结构的变化，以量化植物对波动的水文条件的表型反应。这些数据将用于检验表型灵活性（即，叶和根性状的可塑性）对于在水位波动时预测植物性能将是重要的，但是当水位恒定时，这种可塑性可能降低性能。我们还预测，这三个物种将表现出独特的水处理，反映适应各自的微生境的反应。

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.