Olden Julian D, Poff N LeRoy, Bestgen Kevin R
School of Aquatic and Fishery Sciences, Box 355020, University of Washington, Seattle, Washington 98195, USA.
Ecology. 2008 Mar;89(3):847-56. doi: 10.1890/06-1864.1.
Understanding the causes and consequences of species extinctions is a central goal in ecology. Faced with the difficult task of identifying those species with the greatest need for conservation, ecologists have turned to using predictive suites of ecological and life-history traits to provide reasonable estimates of species extinction risk. Previous studies have linked individual traits to extinction risk, yet the nonadditive contribution of multiple traits to the entire extinction process, from species rarity to local extirpation to global extinction, has not been examined. This study asks whether trait synergisms predispose native fishes of the Lower Colorado River Basin (USA) to risk of extinction through their effects on rarity and local extirpation and their vulnerability to different sources of threat. Fish species with "slow" life histories (e.g., large body size, long life, and delayed maturity), minimal parental care to offspring, and specialized feeding behaviors are associated with smaller geographic distribution, greater frequency of local extirpation, and higher perceived extinction risk than that expected by simple additive effects of traits in combination. This supports the notion that trait synergisms increase the susceptibility of native fishes to multiple stages of the extinction process, thus making them prone to the multiple jeopardies resulting from a combination of fewer individuals, narrow environmental tolerances, and long recovery times following environmental change. Given that particular traits, some acting in concert, may differentially predispose native fishes to rarity, extirpation, and extinction, we suggest that management efforts in the Lower Colorado River Basin should be congruent with the life-history requirements of multiple species over large spatial and temporal scales.
了解物种灭绝的原因和后果是生态学的核心目标。面对确定那些最需要保护的物种这一艰巨任务，生态学家已转向使用一系列生态和生活史特征进行预测，以合理估计物种灭绝风险。以往的研究已将个体特征与灭绝风险联系起来，但多个特征对整个灭绝过程（从物种稀有性到局部灭绝再到全球灭绝）的非累加作用尚未得到研究。本研究探讨特征协同作用是否通过影响稀有性和局部灭绝以及对不同威胁源的脆弱性，使美国科罗拉多河下游流域的本地鱼类面临灭绝风险。与具有简单累加特征效应所预期的情况相比，具有“缓慢”生活史（如体型大、寿命长和成熟延迟）、对后代极少亲代抚育以及特殊摄食行为的鱼类物种，其地理分布范围更小、局部灭绝频率更高且被感知的灭绝风险更高。这支持了这样一种观点，即特征协同作用增加了本地鱼类对灭绝过程多个阶段的易感性，从而使它们容易受到因个体数量减少、环境耐受性狭窄以及环境变化后恢复时间长等因素综合导致的多重危害。鉴于特定特征（有些共同起作用）可能使本地鱼类对稀有性、灭绝和消失有不同的易感性，我们建议科罗拉多河下游流域的管理工作应在大的空间和时间尺度上与多个物种的生活史要求相一致。
