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

表型可塑性，即根据环境调整形态特征的能力，可以在不断变化的环境中提高生存和繁殖能力。鉴于表型可塑性的这种适应价值，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变化方面发挥着重要的理论作用，但相对较少的实证研究关注自然条件下塑性成本的作用。本文的研究将通过研究在各种环境条件下塑性成本和塑性效益之间的平衡来解决这一问题。本文比较了环境变光环境和均匀光环境下草本植物天竺葵（Geranium carolinianum）种群在光有效性方面的可塑性和自然变化模式。可塑性的遗传基础将被评估，因为表型可塑性在未来环境变化中进化的潜力部分取决于其遗传基础。最后，实地研究将检查选择如何在环境可变条件下有利于塑性，而在均匀条件下有利于非塑性响应。随着全球气候变化，预计环境变化会增加。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至关重要。

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.