Abrams Peter A, Matsuda Hiroyuki
Department of Zoology, University of Maryland, College Park, Maryland, 20742.
Population Dynamics of Marine Organisms, Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo, 164, Japan.
Evolution. 1997 Dec;51(6):1742-1750. doi: 10.1111/j.1558-5646.1997.tb05098.x.
We analyze simple models of predator-prey systems in which there is adaptive change in a trait of the prey that determines the rate at which it is captured by searching predators. Two models of adaptive change are explored: (1) change within a single reproducing prey population that has genetic variation for vulnerability to capture by the predator; and (2) direct competition between two independently reproducing prey populations that differ in their vulnerability. When an individual predator's consumption increases at a decreasing rate with prey availability, prey adaptation via either of these mechanisms may produce sustained cycles in both species' population densities and in the prey's mean trait value. Sufficiently rapid adaptive change (e.g., behavioral adaptation or evolution of traits with a large additive genetic variance), or sufficiently low predator birth and death rates will produce sustained cycles or chaos, even when the predator-prey dynamics with fixed prey capture rates would have been stable. Adaptive dynamics can also stabilize a system that would exhibit limit cycles if traits were fixed at their equilibrium values. When evolution fails to stabilize inherently unstable population interactions, selection decreases the prey's escape ability, which further destabilizes population dynamics. When the predator has a linear functional response, evolution of prey vulnerability always promotes stability. The relevance of these results to observed predator-prey cycles is discussed.
我们分析了捕食者 - 猎物系统的简单模型，其中猎物的一个性状存在适应性变化，该性状决定了它被搜索捕食者捕获的速率。探讨了两种适应性变化模型：（1）在单个繁殖猎物种群内部的变化，该种群在被捕食者捕获的易感性方面存在遗传变异；（2）两个独立繁殖的猎物种群之间的直接竞争，它们在易感性方面存在差异。当单个捕食者的消费量随着猎物可获得性的增加而以递减速率增加时，通过这两种机制中的任何一种进行的猎物适应可能会在两个物种的种群密度以及猎物的平均性状值方面产生持续的循环。足够快速的适应性变化（例如，行为适应或具有大的加性遗传方差的性状的进化），或者足够低的捕食者出生率和死亡率将产生持续的循环或混沌，即使具有固定猎物捕获率的捕食者 - 猎物动态原本是稳定的。如果性状固定在其平衡值，适应性动态也可以稳定一个原本会表现出极限环的系统。当进化未能稳定本质上不稳定的种群相互作用时，选择会降低猎物的逃逸能力，这会进一步破坏种群动态。当捕食者具有线性功能反应时，猎物易感性的进化总是会促进稳定性。讨论了这些结果与观察到的捕食者 - 猎物循环的相关性。
