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

0228229 MarquisThis美洲计划论文增强项目将支持卡丽娜·博格女士的论文研究，在密苏里大学圣路易斯分校的罗伯特·J·马奎斯博士的监督下，在墨西哥国立自治大学墨西哥城分校的鲁道夫·迪尔佐博士的协助下。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会改变植物作为食物的相对重要性（即，自下而上的力）和遮蔽物（即，影响自上而下的力量），因为它们影响食草动物。因此，在植物个体发育过程中，植物遭受的植食性的量可能会有所不同。本研究的具体目标是：1）量化墨西哥Chamela热带干旱森林中的新热带树木Casearia corymbosa的防御和营养性状的发育变化; 2）评估Casearia corymbosa的防御性状、植株大小和资源可用性的个体发生变异。伞房花序通过改变植物作为食草动物食物的质量和影响第三级营养级中的一个组分来影响食草动物的密度、群落结构和叶片损害（食虫鸟类）; 3）评估这些变化对植物在不同发育阶段的表现的后果;以及4）确定不同个体发育阶段对草食动物攻击的耐受性的差异程度，并评估这种差异是否是由碳水化合物分配到不同植物器官的变化引起的。 自下而上和自上而下的影响，植物个体发育的相互作用的影响的分析提供了一个机会来描述的同时影响的因素，已被确定为独立影响植物的植食性。此外，在不同的个体发育阶段的防御和耐受策略的评估可以更清楚地了解草食动物对植物适合度的影响，整合不同的抗性策略，植物在生活史中可能会表达，以减少草食动物的负面影响。总之，本研究将有助于我们了解可能影响植物抗性性状进化的因素介导的食草动物和它们的天敌。

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.