DISSERTATION RESEARCH: Exploiting Seasonality and Differences in Herbivory to Create a Novel Framework for Testing Optimal Defense Theory

论文研究：利用草食性的季节性和差异创建测试最佳防御理论的新框架

• 批准号: 1501905
• 负责人: Ruth Hufbauer
• 金额: $ 1.92万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1501905&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Exploiting; Seasonality; Differences

Plants form the basis of most terrestrial food webs, and insect pests consume more plant tissue than all other animals combined. Thus, understanding how plants defend against insect pests is crucial to maintaining important ecosystem services and food production. Compared to old leaves, young leaves are often more valuable to future plant success as well as more nutritious and desirable to insects, but younger tissue may have more defenses against such attack. The mechanisms of plant growth alone might explain this pattern, or it could be an evolutionary adaptation to protect against pests. A series of experiments will test the alternate explanations of growth physiology alone or with defense response using populations of plants that have evolved separately under either low or high levels of insect attack for the last 400 years. The work will incorporate the contributions of undergraduate students.This research will examine a cornerstone of research on plant-insect interactions, the optimal defense theory, which predicts that herbivory selects for young tissues to be better defended than old tissue. However, physiological constraints, as opposed to adaptive responses to selection imposed by herbivory, could lead to the same patterns. In this proposal, I aim to advance understanding of what drives young leaves to be so highly defended by disentangling whether adaptive evolution or physiological constraints drives differences in allocation in defense. To test the alternate hypotheses of physiological constraints versus adaptive evolution, a rigorous new framework of optimal defense will be developed that requires tests of defense to: (1) include root tissue, (2) directly measure relative tissue values, and (3) evaluate how these values change through a growing season. The framework will be tested using an intraspecific comparison between plant populations that predictably vary in their risk of attack (by using European and North American maternal lines of Verbascum thapsis) for specific tissues using pot experiments and measures of tissue value (tissue removal and seed output) and chemical defense allocations.

植物构成了大多数陆地食物网的基础，昆虫消耗的植物组织比所有其他动物的总和还要多。因此，了解植物如何抵御虫害对于维持重要的生态系统服务和粮食生产至关重要。与老叶相比，嫩叶通常对未来植物的成功更有价值，对昆虫来说也更有营养和更有吸引力，但年轻的组织可能对这种攻击有更多的防御。 植物生长的机制本身就可以解释这种模式，或者它可能是一种进化适应，以保护免受害虫的侵害。一系列实验将测试单独的生长生理学或防御反应的替代解释，使用在过去400年中在低或高水平昆虫攻击下分别进化的植物种群。这项工作将包括本科生的贡献。这项研究将检查植物-昆虫相互作用研究的基石，最佳防御理论，该理论预测，草食动物选择年轻组织比老组织更好地防御。然而，生理上的限制，而不是适应性的选择所施加的草食动物，可能会导致相同的模式。在这个提议中，我的目标是通过解开适应性进化或生理约束是否驱动防御分配的差异来促进对是什么驱动嫩叶如此高度防御的理解。为了检验生理约束与适应性进化的替代假设，将开发一个严格的最佳防御新框架，该框架要求防御测试：（1）包括根组织，（2）直接测量相对组织值，以及（3）评估这些值如何通过生长季节变化。该框架将进行测试，使用植物种群之间的种内比较，可预见的不同的攻击风险（通过使用欧洲和北美的毛蕊花的母系）的特定组织，使用盆栽实验和测量的组织价值（组织去除和种子产量）和化学防御分配。