The causes and consequences of species extinctions in food webs

地球目前正在经历第六次大灭绝事件。之前所有的灭绝事件都是由全球性的灾难造成的，这些灾难导致了生态群落的大规模重组。然而，今天的物种灭绝是由人类驱动的，给生态系统带来了与过去大灭绝截然不同的压力。地球上没有不受人为干扰影响的生态系统。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规模丧失、人类福祉所必需的生态系统功能和服务的变化，以及生态群落结构的变化。这类干扰的后果已经研究了几十年，其中一些干扰，如湖泊富营养化的影响，已经得到了很好的理解。然而，令人惊讶的是，我们对干扰如何影响生态群落知之甚少。我们知道，受人类干扰影响严重的群落比受影响较小的群落含有更少的物种和不同的物种；然而，对于人为干扰的后果，我们缺乏一个预测框架。本研究的目的是开发这样一个框架，重点关注两个主要问题。首先，干扰后物种损失的程度如何根据干扰的类型、被干扰的栖息地类型和物种的生活史特征而不同？第二，考虑到不同的干扰会对生态群落产生不同的影响，当不同的群落受到干扰时，物种类型的消失有什么样的总体趋势？回答这些问题很重要，这样我们才能预测干扰的后果。有了关于各种栖息地正在经历的干扰的程度和类型的信息以及上述问题的答案，我们就可以开始预测哪些干扰、哪些栖息地以及哪些物种最需要保护和管理。

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.