Department of Fisheries and Wildlife Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0321, USA.
Conserv Biol. 2010 Oct;24(5):1249-58. doi: 10.1111/j.1523-1739.2010.01488.x.
Conserving rare species and protecting biodiversity and ecosystem functioning depends on sound information on the nature of rarity. Rarity is multidimensional and has a variety of definitions, which presents the need for a quantitative classification scheme with which to categorize species as rare or common. We constructed such a classification for North American freshwater fishes to better describe rarity in fishes and provide researchers and managers with a tool to streamline conservation efforts. We used data on range extents, habitat specificities, and local population sizes of North American freshwater fishes and a variety of quantitative methods and statistical decision criteria, including quantile regression and a cost-function algorithm to determine thresholds for categorizing a species as rare or common. Species fell into eight groups that conform to an established framework for rarity. Fishes listed by the American Fisheries Society (AFS) as endangered, threatened, or vulnerable were most often rare because their local population sizes were low, ranges were small, and they had specific habitat needs, in that order, whereas unlisted species were most often considered common on the basis of these three factors. Species with large ranges generally had few specific habitat needs, whereas those with small ranges tended to have narrow habitat specificities. We identified 30 species not designated as imperiled by AFS that were rare along all dimensions of rarity and may warrant further study or protection, and we found three designated species that were common along all dimensions and may require a review of their imperilment status. Our approach could be applied to other taxa to aid conservation decisions and serve as a useful tool for future revisions of listings of fish species.
保护珍稀物种、保护生物多样性和生态系统功能，取决于对稀有物种本质的准确信息。稀有性具有多维性，且有多种定义，这就需要有一个定量分类方案，以便将物种归类为稀有或常见。我们为北美淡水鱼类构建了这样一个分类系统，以更好地描述鱼类的稀有性，并为研究人员和管理者提供一种工具，以简化保护工作。我们使用了北美淡水鱼类的分布范围、栖息地特异性和局部种群规模的数据，以及各种定量方法和统计决策标准，包括分位数回归和成本函数算法，以确定将物种归类为稀有或常见的阈值。物种分为八个组，符合稀有性的既定框架。美国渔业协会（AFS）列为濒危、受威胁或脆弱的鱼类通常因其局部种群规模低、分布范围小、栖息地需求特定而被视为稀有，而未被列入名单的鱼类通常因其这三个因素而被认为是常见的。分布范围大的物种通常很少有特定的栖息地需求，而分布范围小的物种往往具有狭窄的栖息地特异性。我们确定了 30 种未被 AFS 指定为濒危的稀有物种，这些物种在稀有性的所有维度上都可能需要进一步研究或保护，我们还发现了 3 种被指定为濒危的常见物种，这些物种可能需要重新审查其濒危状态。我们的方法可以应用于其他分类单元，以帮助保护决策，并为未来鱼类物种清单的修订提供有用的工具。
