Predators with Multiple Ontogenetic Niche Shifts Have Limited Potential for Population Growth and Top-Down Control of Their Prey
Predators with Multiple Ontogenetic Niche Shifts Have Limited Potential for Population Growth and Top-Down Control of Their Prey
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具有多个个体发生生态位转变的捕食者的种群增长和自上而下控制猎物的潜力有限
DOI：
10.1086/670614
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
A. D. de Roos
中科院分区：
文献类型：
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作者：
A. van Leeuwen;Magnus Huss;A. Gårdmark;M. Casini;F. Vitale;J. Hjelm;L. Persson;A. D. de Roos
顶级捕食者的灾难性崩溃揭示了自上而下控制的营养级联和群落结构。当人口在崩溃后未能恢复时，这可能表明系统中存在另一种稳定状态。过度捕捞导致了这些动态的几个最引人注目的案例，特别是大西洋鳕鱼种群就是这种缺乏复苏的例证。通常，捕食者物种和幼年捕食者之间的竞争被假设为解释捕食者种群缺乏恢复的原因。然后，捕食者被认为在小的时候与猎物争夺一种资源，然后转移到鱼群。然而，捕食者的生活史往往比这复杂得多，包括多次个体发育的饮食转变。在这里，我们证明了当捕食者在转换到鱼群之前，当捕食者在中间生命阶段以额外的资源(捕食者独有的)为食时，没有替代的稳定状态发生，因为捕食者和捕食者之间的捕食和竞争并不同时构成群落动力学。只有当捕食者对额外的资源没有反馈时，我们才会发现捕食者自上而下地控制着捕食者。否则，捕食者的种群动态受发生在中间生命阶段的个体增长的瓶颈所支配。因此，为捕食者提供额外的资源可能对捕食者种群的增长有利也可能有害，并强烈影响自上而下的群落控制的潜力。
Catastrophic collapses of top predators have revealed trophic cascades and community structuring by top-down control. When populations fail to recover after a collapse, this may indicate alternative stable states in the system. Overfishing has caused several of the most compelling cases of these dynamics, and in particular Atlantic cod stocks exemplify such lack of recovery. Often, competition between prey species and juvenile predators is hypothesized to explain the lack of recovery of predator populations. The predator is then considered to compete with its prey for one resource when small and to subsequently shift to piscivory. Yet predator life history is often more complex than that, including multiple ontogenetic diet shifts. Here we show that no alternative stable states occur when predators in an intermediate life stage feed on an additional resource (exclusive to the predator) before switching to piscivory, because predation and competition between prey and predator do not simultaneously structure community dynamics. We find top-down control by the predator only when there is no feedback from predator foraging on the additional resource. Otherwise, the predator population dynamics are governed by a bottleneck in individual growth occurring in the intermediate life stage. Therefore, additional resources for predators may be beneficial or detrimental for predator population growth and strongly influence the potential for top-down community control.