Linking Rarity, Extinction Dynamics, and Life-History Traits: Across-Scale Investigations with Desert Fishes

灭绝是生态学中最基本的过程之一，它决定着生物多样性的进化、群落结构和模式。然而，关于物种灭绝的研究很少，涉及硬数据而非理论模型的研究几乎完全缺乏。我们将利用一个关于索诺兰沙漠鱼类的非凡数据库来研究灭绝与稀有模式和生活史特征之间的关系。我们项目的关键是开发新的方法来量化稀有度的模式，这些模式独立于分析的空间尺度。对稀有性的调查很重要，因为大多数物种在某种程度上都是稀有的。物种在“稀有的方式”（如数量、空间分布）上的差异的细节可能是理解生态学多样性问题的关键，包括群落的聚集和物种如何在面对干扰时持续存在。我们独特的数据库包括超过25,000个地点记录，跨越160年的实地研究，涵盖索诺兰沙漠鱼类的所有50个已知分类群。这些鱼类共同构成了一种严重濒危的生物群，关于它们的稀有性、灭绝倾向和生活史特征之间联系的数据具有重要的保护意义。我们采用的方法是对Kunin（1998）的“尺度-面积曲线”概念的修改，该概念提供了一种跨空间尺度量化稀有模式的方法。具体来说，我们将研究这些鱼类的稀有模式如何与它们的灭绝动态（例如，灭绝事件的频率和空间格局）和当前的濒危程度相关。我们还将确定在何种程度上稀有和灭绝的模式可以通过生活史属性来预测。生物多样性数据库是一个未开发的物种分布信息仓库。它们使我们能够在不同的尺度上提出问题，并且比任何实验或集中的实地研究都具有更大的分类广度。它们也允许我们提出完全不同的问题——比如关于灭绝的问题。这里提出的研究将探索稀有、灭绝风险和生活史特征之间的联系，同时定义如何使用现有数据库的限制，并阐明如何改进新数据库的开发。

William FaganDEB 0075667ABSTRACTExtinction is one of the most fundamental processes in ecology-it shapes evolution, community structure, and patterns of biodiversity. Yet studies of extinction are scarce, and studies involving hard data rather than theoretical models are almost totally lacking. We will take advantage of an extraordinary database concerning Sonoran Desert fishes to investigate relationships between extirpation and patterns of rarity and life-history traits. Key to our project is the development of new methods for quantifying patterns of rarity that are independent of the spatial scale of analyses. Investigations of rarity are important because most species are in some way rare. The details of how species differ in the "way in which they are rare" (e.g., in numbers, in spatial distribution) may be key to understanding a diversity of issues in ecology, including the assembly of communities and how species persist in the face of disturbances. Our unique database includes over 25,000 locality records spanning 160 years of field research for all 50 known taxa of Sonoran Desert fishes. These fishes collectively constitute a gravely endangered biota for which data on the linkages among rarity, extinction-proneness, and life-history traits are of critical conservation importance. The methods we apply are modifications of Kunin's (1998) notion of "scale-area curves," which provide a means of quantifying rarity patterns across spatial scales. Specifically, we will examine how the patterns of rarity these fish exhibit relate to their extinction dynamics (e.g., frequency and spatial pattern of extirpation events) and current levels of endangerment. We will also determine the extent to which patterns of rarity and extinction can be predicted by life-history attributes. Biodiversity databases are an untapped storehouse of information on distributions of species. They allow us to ask questions at different scales and with greater taxonomic breadth than any experiment or focused field study can. They also allow us to ask altogether different questions-such as questions about extinction. The research proposed here will explore linkages between rarity, extinction risk, and life-history traits, along the way defining limits on how existing databases can be used and clarifying how to improve development of new databases.