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

虽然在过去的一个世纪里，互助者竞争的概念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记录它的发生。这种缺失对于同翅目-蚂蚁协会来说尤为明显。这项拟议的研究旨在从实验上评估这样一种假设，即相邻的同翅目聚集物在种内竞争蚂蚁互助者的服务。人工操作实验已经证明，在大多数年份里，隐形蚁对膜酸阳蝇的饲养是有好处的。一系列实验将评估以下假设：(1)蚂蚁是膜酸的有限资源，(2)照顾膜酸的蚂蚁的数量，而不仅仅是蚂蚁的存在，对膜酸的适合性有重大影响，(3)寄主植物品质的种内和种间差异影响了膜酸蜜露的化学成分，从而影响了膜酸对蚂蚁的竞争能力；(4)照顾蚂蚁通过减少捕食性蜘蛛(Pellenes sp.)的影响而使膜酸受益。这样的实验研究将提供所需的洞察力，以了解在空间可变的环境中相互作用的动力学。

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.