Shurin J B, Allen E G
Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, USA.
Am Nat. 2001 Dec;158(6):624-37. doi: 10.1086/323589.
This study explores the consequences of predator-mediated coexistence among competitors for patterns of incidence and diversity at local and regional scales. We develop a model that draws on elements of metapopulation models of competitors and food chains by allowing competitors to coexist locally in the presence of predators but not in their absence. The model predicts that predators promote regional coexistence by greatly expanding the range of conditions under which two competitors persist at equilibrium. Predators could have positive or negative effects on mean local diversity within the region depending on their dispersal rates, those of the prey, and their effects on prey extinction rates. The presence of predators increased the abundance of inferior competitors, thereby expanding the conditions for positive relationships between local and regional diversity. The model also predicted positive correlations between local diversity of predators and prey. These predictions were supported by patterns of phytoplankton, zooplankton, and fish species richness among lakes. The model may help to resolve the apparent contrast between linear patterns of local and regional richness and experimental evidence for strong invasion resistance and rapid dispersal in zooplankton.
本研究探讨了捕食者介导的竞争者共存对局部和区域尺度上的发病率和多样性模式的影响。我们开发了一个模型，该模型借鉴了竞争者和食物链的集合种群模型的元素，通过允许竞争者在有捕食者存在的情况下在局部共存，而在没有捕食者的情况下则不能共存。该模型预测，捕食者通过大大扩展两种竞争者在平衡状态下持续存在的条件范围来促进区域共存。捕食者对区域内平均局部多样性可能产生正面或负面影响，这取决于它们的扩散率、猎物的扩散率以及它们对猎物灭绝率的影响。捕食者的存在增加了劣势竞争者的丰度，从而扩大了局部和区域多样性之间呈正相关关系的条件。该模型还预测了捕食者和猎物的局部多样性之间存在正相关。这些预测得到了湖泊中浮游植物、浮游动物和鱼类物种丰富度模式的支持。该模型可能有助于解决局部和区域丰富度的线性模式与浮游动物具有强大入侵抗性和快速扩散的实验证据之间的明显矛盾。
