Dissertation Research: The Maintenance of Genetic Variation for Phenotypic Plasticity: The Roles of Cost and Adaptation

表型可塑性，即对环境做出反应而调整形态特征的能力，可能会提高在不断变化的环境中的生存和繁殖。鉴于表型可塑性的这种适应性价值，了解可能维持可塑性遗传变异的机制是很重要的。尽管塑性成本在维持这种差异方面发挥了重要的理论作用，但相对较少的实证研究集中在自然条件下塑性成本的作用。本论文的研究将通过考察各种环境条件下的可塑性成本和可塑性收益之间的平衡来解决这一问题。对来自环境可变和均匀光照环境的草本植物老爷草种群的可塑性模式与自然变化的光照条件进行了比较。可塑性的遗传基础将被评估，因为表型可塑性随着未来环境变化而进化的潜力在一定程度上取决于其遗传基础。最后，一项实地研究将考察选择如何在环境可变的条件下有利于可塑性，而在一致的条件下有利于非塑性反应。随着全球气候变化，环境变化预计会增加。了解可塑性是如何维持的，对于预测种群对不同环境的反应是至关重要的。

Phenotypic plasticity, the ability to adjust morphological traits in response to the environment, may enhance survival and reproduction in changing environments. Given this adaptive value of phenotypic plasticity, it is important to understand the mechanisms that may maintain genetic variation for plasticity. Despite the important theoretical role the cost of plasticity plays in maintaining this variation, relatively few empirical studies have focused on the role of cost of plasticity under natural conditions. This dissertation research will address this issue by examining the balance between the cost of plasticity and the benefit of plasticity under a variety of environmental conditions. Populations of the herbaceous plant Geranium carolinianum from both environmentally variable and uniform light environments are compared for the patterns of plasticity to natural variation in light availability. The genetic basis of plasticity will be assessed because the potential of phenotypic plasticity to evolve in response to future environmental change depends in part on its genetic basis. Finally, a field study will examine how selection may favor plasticity under environmentally variable conditions but favor non-plastic responses under uniform conditions. An increase in environmental variation is expected with global climate change. Understanding how plasticity is maintained is central to predicting population response to diverse environments.