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

0228229Marquis这个美洲项目论文增强项目将支持Karina Boege女士的论文研究，在密苏里大学圣路易斯市的Robert J. Marquis博士的指导下。在墨西哥国立自治大学（UNAM）的Rodolfo Dirzo博士的协助下。该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改变植物作为食物（即自下而上的力量）和庇护所（即影响自上而下的力量）的相对重要性，因为它们影响食草动物。因此，在植物个体发育过程中，植物遭受的草食量可能会发生变化。此外，受食草动物攻击影响，植物在不同发育阶段的耐受性变化也会影响植物的生产性能。本研究的具体目的是：1)量化墨西哥Chamela热带干燥森林新热带乔木Casearia corymbosa的防御和营养性状的发育变化；2)通过对草食植物品质的改良和第三营养层（食虫鸟类）的影响，评估石斛防御性状、植株大小和资源可利用性的个体发生变异对草食动物密度、群落结构和叶片损害的影响；3)评估这些变化对不同发育阶段植物性能的影响；4)确定不同个体发育阶段对草食攻击耐受性的差异程度，并评估这种差异是否与植物不同器官碳水化合物分配的变化有关。对受植物个体发育影响的自下而上和自上而下的相互作用的分析提供了一个机会来描述已经确定的独立影响植物接受的草食的因素的同时作用。此外，对不同个体发育阶段的防御和耐受策略进行评估，可以更清楚地了解草食对植物适合度的影响，整合植物在生活史中可能表达的不同抗性策略，以减少草食的负面影响。总之，本研究将有助于我们了解食草动物及其天敌介导的植物抗性性状进化的影响因素。

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.