U.S.-Mexico Dissertation Research: Ontogenetic Variation In Plant Response: Consequences For Herbivores and Plants

0228229马奎斯该美洲计划论文增强项目将支持卡琳娜·博格女士在密苏里大学圣彼得堡分校罗伯特·J·马奎斯博士的指导下进行的论文研究。路易斯在墨西哥城国家自治大学鲁道夫·迪尔佐博士的协助下进行了这项工作。这项研究将评估与植物发育相关的植物质量、结构和耐受性变化的后果。植物质量和结构的变化可能会改变植物在影响草食动物时作为食物(即自下而上的作用力)和庇护所(即影响自上而下的作用力)的相对重要性。因此，在植物个体发育期间，植物遭受的食草性疾病的数量可能会有所不同。本研究的具体目标是：1)量化墨西哥查梅拉热带干燥森林中的一种新热带乔木木麻黄的防御和营养性状的发育变化；2)通过改变作为草食动物食物的植物质量以及第三营养级的一种成分(食虫鸟类)，评估这些变化对植物在不同发育阶段的表现的影响；4)确定不同个体发育阶段对食草动物攻击的耐受性差异程度，并评估碳水化合物分配到不同植物器官的变化是否促进了这种差异。对自下而上和自上而下受植物个体发育影响的相互影响的分析提供了一个机会来描述已被确定为独立影响植物接收草食的因素的同时影响。此外，在个体发育的不同阶段对防御和耐受策略的评估有助于更清楚地了解草食对植物适合性的影响，整合植物在生活史上可能表达的不同抗性策略，以减少草食的负面影响。总之，这项研究将有助于我们理解可能影响草食动物及其天敌介导的植物抗性性状进化的因素。

0228229MarquisThis Americas Program thesis enhancement project will support dissertation research by Ms. Karina Boege, under the supervision of Dr. Robert J. Marquis of the University of Missouri-St. Louis, with the assistance of Dr. Rodolfo Dirzo of the Universidad Nacional Autonoma de Mexico, UNAM in Mexico City. The research will evaluate the consequences of changes in plant quality, architecture, and tolerance associated with plant development. Changes in plant quality and architecture may modify the relative importance of plants as food (i.e., bottom-up forces) and shelter (i.e., influencing top-down forces) as they affect herbivores. As a result, the amount of herbivory a plant suffers may vary during plant ontogeny. Moreover, changes in tolerance will influence plant performance at different developmental stages as affected by herbivore attack.Specific objectives of this study are to: 1) quantify developmental changes in defensive and nutritional traits of Casearia corymbosa, a neotropical tree in the tropical dry forest of Chamela, Mexico; 2) evaluate how ontogenetic variation in defensive traits, plant size, and resource availability for C. corymbosa affects herbivore density, community structure, and leaf damage, through the modification of plant quality as food for herbivores and the impacts of one component of the third trophic level (insectivorous birds); 3) assess the consequences of such changes for plant performance at different developmental stages; and 4) determine the degree to which different ontogenetic stages differ in tolerance to herbivore attack, and evaluate if such differences are promoted by changes in carbohydrate allocation to different plant organs. The analysis of the interactive impacts of bottom-up and top-down forces as influenced by plant ontogeny provides an opportunity to describe the simultaneous effects of factors that have been identified to independently influence herbivory received by plants. In addition, the evaluation of both defensive and tolerance strategies at different ontogenetic stages allows a clearer understanding of the impacts of herbivory on plant fitness, integrating the different resistance strategies that plants may express during life-history to reduce the negative impacts of herbivory. Overall, this study will contribute to our understanding of the factors that may influence the evolution of plant resistance traits mediated by herbivores and their natural enemies.