Infectious Agents Trigger Trophic Cascades. (September 2017)

• Record Type: Journal Article
• Authors: Buck, Julia C.; Ripple, William J.
• Is Part Of: Trends in ecology & evolution. Volume 32:Number 9(2017)
• Page Start: 681
• Page End: 694
• Publication Date: 2017-09
• Subjects: biological control -- consumer strategy -- keystone -- natural enemy -- top-down regulation -- tritrophic; Ecology -- Periodicals; Evolution (Biology) -- Periodicals; 576.8
• DOI: 10.1016/j.tree.2017.06.009
• Languages: English
• ISSNs: 0169-5347

Abstract

Abstract : 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. Trends: Trophic cascades originate with consumers (predators or infectious agents). The frequency of trophic cascades reported for different consumer types scales with consumer lethality. Unlike most predators, infectious agents can consume (i.e., infect) a victim without killing it. This raises the potential for infectious agents to cause consumptive trait-mediated indirect effects, which can be positive or negative. Infectious agents seem less likely than predators to cause consumptive density-mediated indirect effects and nonconsumptive trait-mediated indirect effects, but are uniquely capable of causing consumptive trait-mediated indirect effects. Unification of predator–prey and parasite–host theory under a general consumer–resource framework will benefit both fields.