Dissertation Research: Intraspecific Competition for Mutualists: Conditional Interactions in a Membracid-Ant Association

虽然共生竞争的概念在过去的一个世纪里引起了相当大的关注，但很少有研究提供直接的实验证据来证明它的发生。这种缺失在同翅蚁的关联中尤为明显。本研究旨在通过实验验证一种假设，即邻近的同翅类群体会在种内竞争蚂蚁共生者的服务。以前的操纵实验已经证明，在大多数年份里，膜类昆虫耻花（同翅目）受益于隐蔽蚁群的照料。一系列的实验将评估以下假设：(1)蚂蚁是膜类植物的有限资源；(2)照料膜类植物的蚂蚁数量，而不仅仅是蚂蚁的存在，对膜类植物的适合度有显著影响；(3)寄主植物质量的种内和种间变化影响膜类植物蜜露的化学成分，从而影响膜类植物竞争蚂蚁的能力。(4)抚育蚂蚁通过减少掠食性蜘蛛（Pellenes sp.）的影响而有利于膜纲。这样的实验研究将为在空间可变的环境中相互作用的动力学提供必要的见解。

While the concept of competition for mutualists has attracted considerable attention during the past century, few studies have provided direct experimental evidence documenting its occurrence. This absence is particularly evident for homopteran-ant associations. The proposed research is designed to experimentally evaluate the hypothesis that neighboring homopteran aggregations intraspecifically compete for the services of an ant mutualist. Manipulative experiments have previously demonstrated that the membracid Publilia modesta (Homoptera) benefits from being tended by the ant Formica occulta in most years. A series of experiments will evaluate the following hypotheses: (1) ants are a limited resource for membracids, (2) the number of ants tending membracids, and not just the presence of ants, has a significant impact on membracid fitness, (3) intra- and interspecific variation in host-plant quality influences the chemical composition of membracid honeydew and therefore the ability of membracids to compete for ants, and (4) tending ants benefit membracids by reducing the impact of predatory spiders (Pellenes sp.). Such experimental studies will provide needed insight into the dynamics of mutualistic interaction in spatially-variable environments.