Am Nat. 2019 May;193(5):E132-E148. doi: 10.1086/701780. Epub 2019 Mar 7.
Predator avoidance behavior, in which prey limit foraging activities in the presence of predation threats, affects the dynamics of many ecological communities. Despite the growing theoretical appreciation of the role predation plays in coexistence, predator avoidance behavior has yet to be incorporated into the theory in a general way. We introduce adaptive avoidance behavior to a consumer-resource model with three trophic levels to ask whether the ability of prey-the middle trophic level-to avoid predators alters their ability to coexist. We determine the characteristics of cases in which predator avoidance behavior changes prey coexistence or the order of competitive dominance. The mechanism underlying such changes is the weakening of apparent competition relative to resource competition in determining niche overlap, even with resource intake costs. Avoidance behavior thus generally promotes coexistence if prey partition resources but not predators, whereas it undermines coexistence if prey partition predators but not resources. For any given case, the changes in the average fitness difference between two species resulting from avoidance behavior interact with changes in niche overlap to determine coexistence. These results connect the substantial body of theoretical work on avoidance behavior and population dynamics with the body of theory on competitive coexistence.
回避捕食者的行为，即猎物在捕食威胁下限制觅食活动，影响着许多生态群落的动态。尽管人们越来越认识到捕食在共存中所起的作用，但回避捕食者的行为尚未被普遍纳入理论中。我们在一个具有三个营养级的消费者-资源模型中引入适应性回避行为，以探讨猎物（中间营养级）回避捕食者的能力是否会改变它们共存的能力。我们确定了回避行为改变猎物共存或竞争优势顺序的案例特征。这种变化的基础机制是，在确定生态位重叠时，与资源竞争相比，明显竞争相对减弱，即使存在资源摄入成本也是如此。因此，如果猎物分割资源而不是捕食者，回避行为通常会促进共存，而如果猎物分割捕食者而不是资源，则会破坏共存。对于任何给定的情况，回避行为导致的两个物种平均适应度差异的变化与生态位重叠的变化相互作用，从而决定共存。这些结果将关于回避行为和种群动态的大量理论工作与关于竞争共存的理论联系起来。
