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。以前的所有灭绝事件都是由全球灾难推动的，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推动的，导致生态系统面临的压力与过去的大规模灭绝截然不同。地球上没有不受人类干扰影响的生态系统。物种入侵、污染、富营养化、气候变化和资源的采伐导致了生物多样性的大量丧失，改变了人类福祉所必需的生态系统功能和服务，并改变了生态社区的结构。几十年来，人们一直在探索这类干扰的后果，对于一些干扰，如湖泊富营养化的影响，人们已经非常了解。然而，有些令人惊讶的是，我们对干扰如何影响生态社区的总体了解是如此之少。我们知道，受人类干扰严重影响的社区比受影响较小的社区包含的物种和不同物种更少；然而，我们缺乏关于人类干扰后果的预测框架。本研究的目的是建立这样一个框架，着重于两个主要问题。首先，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，干扰后物种损失的程度有何不同？其次，鉴于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，它们失去的物种类型存在哪些总体趋势？回答这些问题很重要，这样我们才能预测骚乱的后果。根据不同栖息地正在经历的干扰程度和类型的信息以及上述问题的答案，我们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.