Understanding how predators affect prey populations is a fundamental goal for ecologists and wildlife managers. A well‐known example of regulation by predators is the predator pit, where two alternative stable states exist and prey can be held at a low density equilibrium by predation if they are unable to pass the threshold needed to attain a high density equilibrium. While empirical evidence for predator pits exists, deterministic models of predator–prey dynamics with realistic parameters suggest they should not occur in these systems. Because stochasticity can fundamentally change the dynamics of deterministic models, we investigated if incorporating stochasticity in predation rates would change the dynamics of deterministic models and allow predator pits to emerge. Based on realistic parameters from an elk–wolf system, we found predator pits were predicted only when stochasticity was included in the model. Predator pits emerged in systems with highly stochastic predation and high carrying capacities, but as carrying capacity decreased, low density equilibria with a high likelihood of extinction became more prevalent. We found that incorporating stochasticity is essential to fully understand alternative stable states in ecological systems, and due to the interaction between top–down and bottom–up effects on prey populations, habitat management and predator control could help prey to be resilient to predation stochasticity.

中文翻译：

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随机捕食使猎物暴露于捕食者的坑中并局部灭绝

了解捕食者如何影响猎物种群是生态学家和野生动植物管理者的基本目标。捕食者调节的一个众所周知的例子是捕食者坑，那里存在两个替代的稳定状态，如果捕食者无法通过达到高密度平衡所需的阈值，则可以通过捕食将其保持在低密度平衡下。尽管存在捕食坑的经验证据，但是具有现实参数的捕食者-被捕食动力学的确定性模型表明，它们不应出现在这些系统中。因为随机性可以从根本上改变确定性模型的动力学，所以我们研究了将随机性纳入捕食率是否会改变确定性模型的动力学并允许掠食者坑出现。根据麋鹿-狼系统的实际参数，我们发现只有在模型中包含随机性时，才能预测捕食者的坑。在具有高度随机捕食和高承载能力的系统中出现了捕食坑，但是随着承载能力的降低，低密度平衡和灭绝的可能性变得越来越普遍。我们发现，纳入随机性对于充分了解生态系统中的替代稳定状态至关重要，并且由于自上而下和自下而上对猎物种群的相互作用，栖息地管理和捕食者控制可以帮助猎物适应捕食的随机性。具有高度灭绝可能性的低密度平衡变得更加普遍。我们发现，纳入随机性对于充分了解生态系统中的替代稳定状态至关重要，并且由于自上而下和自下而上对猎物种群的相互作用，栖息地管理和捕食者控制可以帮助猎物适应捕食的随机性。具有高度灭绝可能性的低密度平衡变得更加普遍。我们发现，纳入随机性对于充分了解生态系统中的替代稳定状态至关重要，并且由于自上而下和自下而上对猎物种群的相互作用，栖息地管理和捕食者控制可以帮助猎物适应捕食的随机性。