Twombly S, Wang Guiming, Hobbs N Thompson
Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island 02881, USA.
Ecology. 2007 Mar;88(3):658-70. doi: 10.1890/06-0423.
Understanding the processes that control species abundance and distribution is a major challenge in ecology, yet for a large number of potentially important organisms, we know little about the biotic and abiotic factors that influence population size. One group of aquatic organisms that defies traditional demographic analyses is the Crustacea, particularly those with complex life cycles. We used likelihood techniques and information theoretics to evaluate a suite of models representing alternative hypotheses on factors controlling the abundance of two copepod crustaceans in a small, tropical floodplain lake. Quantitative zooplankton samples were collected at three stations in a Venezuelan floodplain lake from June through December 1984; the average sampling interval was two days. We constructed a series of models with stage structure that incorporated six biotic and abiotic covariates in various combinations to account for temporal changes in abundance of these target species and in their population growth rates. Our analysis produced several novel insights into copepod population dynamics. We found that multiple forces affected the abundance of particular stages, that these factors differed between species as well as among stages within each species, and that biotic processes had the largest effects on copepod population dynamics. Density dependence had a large effect on the survival of Oithona amazonica copepodites and on population growth rate of Diaptomus negrensis.
理解控制物种丰度和分布的过程是生态学中的一项重大挑战，然而对于大量潜在重要的生物，我们对影响种群规模的生物和非生物因素知之甚少。一类难以进行传统种群统计学分析的水生生物是甲壳纲动物，尤其是那些具有复杂生命周期的种类。我们使用似然技术和信息理论来评估一系列模型，这些模型代表了关于控制一个小型热带洪泛平原湖泊中两种桡足类甲壳动物丰度的因素的不同假设。1984年6月至12月期间，在委内瑞拉一个洪泛平原湖泊的三个站点采集了定量浮游动物样本；平均采样间隔为两天。我们构建了一系列具有阶段结构的模型，这些模型以各种组合纳入了六个生物和非生物协变量，以解释这些目标物种的丰度及其种群增长率的时间变化。我们的分析对桡足类种群动态产生了一些新的见解。我们发现多种力量影响特定阶段的丰度，这些因素在不同物种之间以及每个物种的不同阶段之间存在差异，并且生物过程对桡足类种群动态的影响最大。密度依赖对亚马逊乳点水蚤桡足幼体的存活以及黑氏镖水蚤的种群增长率有很大影响。
