Disturbance, competition and the invertebrate predator guild of high gradient coastal streams

了解决定生物多样性和群落物种组成的生态和进化因素是当今最重要的科学挑战之一，部分原因是这是预测人类活动对生态系统影响的先决条件。这也是最艰巨的挑战之一。尽管干扰（如火灾、飓风、洪水）是许多生态系统的正常组成部分，但它们对群落结构的短期和长期影响各不相同。干扰，定义为一个离散的事件，删除个人或生物量，可以排除物种，导致更多的物种，改变相对丰度，和/或改变一个社区的物理或生物环境。 在这项研究中，我期待在流（洪水）的干扰的后果，其影响共存与公会的捕食性无脊椎动物（石蝇和石蛾）。由于竞争能力和对干扰的反应之间的权衡会影响共存竞争者的数量，因此关键的测量是对干扰的敏感性和对竞争的敏感性。我建议使用一个3管齐下的方法来检查的作用，在高梯度，沿海流的无脊椎动物捕食者的共存中发挥的流动变化的形式的干扰。我将确定（1）如果（以及如何）物种丰富度的无脊椎动物捕食者与干扰制度，（2）的主要机制，干扰影响物种共存的捕食者公会和（3）如何以及为什么干扰流（地质，地貌，土地利用）之间的变化。

Understanding the ecological and evolutionary factors that determine the biodiversity and species composition of communities is one of the most important scientific challenges today, in part because it is a pre-requisite to predicting the consequences that human activities will have on ecosystems. It is also one of the most daunting challenges. Even though disturbances (e.g. fires, hurricanes, floods) are a normal part of many ecosystems, they have variable short and long term effects on community structure. Disturbance, defined as a discrete event removing individuals or biomass, can exclude species, lead to the inclusion of more species, alter relative abundances, and/or change the physical or biotic environment of a community. In this study I look at the consequences of disturbance in streams (floods) in the light of its effect on coexistence with the guild of predatory invertebrates (stoneflies and caddisflies). Since trade-offs between competitive ability and response to disturbance can affect the number of coexisting competitors, the critical measurements are sensitivity to the disturbance and sensitivity to competition. I propose to use a 3-pronged approach to examining the role that disturbance in the form of flow variability plays in the coexistence of invertebrate predators in high gradient, coastal streams. I will determine (1) if (and how) species richness of invertebrate predators is related to disturbance regime, (2) the primary mechanisms by which disturbance affects species coexistence within the predator guild and (3) how and why disturbance varies among streams (geology, geomorphology, land use).