Marine Science Institute, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
Global Trophic Cascades Program, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331, USA.
Trends Ecol Evol. 2017 Sep;32(9):681-694. doi: 10.1016/j.tree.2017.06.009. Epub 2017 Jul 20.
Most demonstrated trophic cascades originate with predators, but infectious agents can also cause top-down indirect effects in ecosystems. Here we synthesize the literature on trophic cascades initiated by infectious agents including parasitoids, pathogens, parasitic castrators, macroparasites, and trophically transmitted parasites. Like predators, infectious agents can cause density-mediated and trait-mediated indirect effects through their direct consumptive and nonconsumptive effects respectively. Unlike most predators, however, infectious agents are not fully and immediately lethal to their victims, so their consumptive effects can also trigger trait-mediated indirect effects. We find that the frequency of trophic cascades reported for different consumer types scales with consumer lethality. Furthermore, we emphasize the value of uniting predator-prey and parasite-host theory under a general consumer-resource framework.
大多数表现出的营养级联起源于捕食者，但传染性病原体也可以在生态系统中引起自上而下的间接影响。在这里，我们综合了有关传染性病原体引发的营养级联的文献，包括寄生蜂、病原体、寄生性去势者、大型寄生虫和营养传递寄生虫。与捕食者一样，传染性病原体可以通过直接消耗和非消耗效应分别引起密度介导和特征介导的间接效应。然而，与大多数捕食者不同的是，传染性病原体不会对其受害者完全和立即致命，因此它们的消耗效应也可以引发特征介导的间接效应。我们发现，报告的不同消费者类型的营养级联频率与消费者的致死率成正比。此外，我们强调了在一般的消费者-资源框架下统一捕食者-猎物和寄生虫-宿主理论的价值。
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