Dissertation Research: Role of Light in Determining the Costs and Benefits of Extrafloral Nectar Production in Two Costa Rican Passiflora Species

尽管许多研究人员提出植物防御成本和草食成本之间的平衡影响了植物采用的防御类型和这些防御在植物结构中的分布，迄今为止，还没有研究以定量的方式充分评估这些成本，也没有人确定这些成本是如何受到植物获得光线和其他资源的影响的。为了解决这个问题，我们将研究两种密切相关的西番莲种在不同光照条件下的花外花蜜生产成本之间的关系。拟议的项目比以前研究国防成本和效益的方法有几个优点。花外花蜜，不像许多有毒的化学防御，有一个简单的化学成分，可以用一种非破坏性的方式来测量。此外，可以通过比较未经处理的植物和排除蚂蚁的植物来评估与花外花蜜生产相关的保护作用。最后，利用种群投影矩阵来模拟植物生长，防御和食草成本可以用适应度分量来表示。因此，以花外花蜜为基础的蚂蚁防御可能是研究叶片防御成本和收益的理想系统。

Although many researchers propose that the balance between costs of plant defenses and the cost of herbivory have influenced both the types of defenses a plant employs and the distribution of those defenses among plant structure, no study to date has fully evaluated these costs in a quantitative fashion nor has anyone determined how these costs are affected by the plant's access to light and other resources. To address this question, the relationship between costs of extrafloral nectar production in two closely related Passiflora species that differ in the range of light conditions in which they grow will be studied. The proposed project provides several advantages over previous approaches to the study of costs and benefits of defense. Extrafloral nectar, unlike many toxic chemical defenses, has a simple chemical composition and can be measured in a non-destructive fashion. Further, protection associated with extrafloral nectar production can be evaluated by comparing untreated plants to plants from which ants have been excluded. Finally, by using population projection matrices to model plant growth, the costs of defense and herbivory can be expressed in terms of a fitness component. Thus, extrafloral nectar-based ant defense may represent an ideal system for the study of costs and benefits of leaf defense.