The causes and consequences of species extinctions in food webs

地球正在经历第六次大规模灭绝事件。所有以前的灭绝事件都是由全球性灾难造成的，这些灾难导致了生态群落的大规模重组。然而，今天的灭绝是由人类驱动的，这导致了一系列与过去大规模灭绝相比非常不同的生态系统压力。地球上没有一个生态系统不受人为干扰的影响。物种入侵、污染、富营养化、气候变化和资源采伐导致了生物多样性的大量丧失，人类福祉所必需的生态系统功能和服务发生了变化，生态群落的结构也发生了变化。这些类型的干扰的后果已经探索了几十年，对于一些干扰，如湖泊富营养化的影响，是非常清楚的。然而，令人惊讶的是，我们对干扰如何影响生态群落的了解甚少。我们知道，受人类干扰严重影响的社区比受影响不那么严重的社区包含更少的物种和不同的物种;然而，我们缺乏对人类干扰后果的预测框架。本研究的目标是建立这样一个框架，重点是两个主要问题。第一，干扰后物种损失的程度如何根据干扰的类型、被干扰的生境类型和物种的生活史特征而有所不同？第二，鉴于不同的干扰对生态群落的影响不同，当它们受到干扰时，从不同群落中消失的物种类型存在什么一般趋势？弄清这些问题是很重要的，这样我们就可以预测扰动的后果。有了关于各种生境正在经历的干扰的程度和类型的信息以及对上述问题的答案，我们就可以开始预测哪些干扰、哪些生境和哪些物种需要最多的保护和管理关注。

The Earth is currently experiencing its sixth mass extinction event. All previous extinction events have been driven by global catastrophes that have resulted in massive reorganization of ecological communities. Today however extinction is driven by humans leading to a very different set of pressures on ecosystems than the mass extinctions of the past. There are no ecosystems on Earth that have been unaffected by human-mediated disturbance. Species invasions, pollution, eutrophication, climate change, and harvesting of resources have led to massive losses of biodiversity, changes in ecosystem functions and services that are necessary to human well-being, and changes in how ecological communities are structured. The consequences of these types of disturbances have been explored for decades and for some disturbances, such as the effects of eutrophication in lakes, are very well-understood. It is somewhat surprising however how little we understand about how disturbance affects ecological communities in general. We know that communities heavily impacted by human disturbances contain fewer species and different species than communities that are less heavily impacted; however we lack a predictive framework for the consequences of human disturbance. The objective of this research is to develop such a framework focusing on two main questions. First, how does the magnitude of species loss following disturbance differ based on the type of disturbance, the habitat type that is being disturbed, and the life history traits of species? Second, given that different disturbances will affect ecological communities differently, what general trends exist in the types of species that are lost from various communities when they are disturbed? Answering these questions is important so that we can predict the consequences of disturbances. Given information about the extent and type of disturbances that various habitats are experiencing and the answers to the questions above we can begin to make predictions about which disturbances, which habitats, and which species need the most conservation and management attention.