Virulent Disease Epidemics Can Increase Host Density by Depressing Foraging of Hosts
Virulent Disease Epidemics Can Increase Host Density by Depressing Foraging of Hosts
复制标题
强毒流行病可以通过抑制宿主的觅食来增加宿主密度
DOI：
10.1086/717175
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Hall, Spencer R.
中科院分区：
文献类型：
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作者：
Penczykowski, Rachel M.;Shocket, Marta S.;Ochs, Jessica Housley;Lemanski, Brian C.;Sundar, Hema;Duffy, Meghan A.;Hall, Spencer R.
在其他条件相同的情况下，损害宿主健康的寄生虫应该会降低宿主的密度。然而，改变寄主性状的寄生虫可能通过间接的生态相互作用增加寄主密度。在这里，我们展示了受感染宿主觅食率的降低是如何产生这种水螅效应的。利用觅食实验，我们量化了感染了一种毒性真菌寄生虫的浮游动物宿主的觅食率降低。然后，我们用这个觅食功能参数化了宿主、寄生虫和资源的动态模型，展示了觅食抑制如何产生水螅效应。从数学上讲，当资源生产率的增长超过每台主机资源消耗的增长时，九头蛇就会出现。因此，觅食介导的水螅效应更有可能出现在(1)对物流类资源有强烈控制的宿主和(2)中等毒性寄生虫大规模流行期间。然后，我们分析了13种自然界真菌流行的流行病。我们发现了觅食介导水螅效应的证据：大规模爆发降低了觅食率，并与藻类资源和水蚤宿主密度的增加相关。因此，即使在增加宿主死亡率的寄生虫流行期间，降低受感染宿主的觅食率也可以产生更高的宿主密度。这种水螅可能会防止宿主种群的崩溃，但也可能产生更高密度的受感染宿主。
All else equal, parasites that harm host fitness should depress densities of their hosts. However, parasites that alter host traits may increase host density via indirect ecological interactions. Here, we show how depression of foraging rate of infected hosts can produce such a hydra effect. Using a foraging assay, we quantified reduced foraging rates of a zooplankton host infected with a virulent fungal parasite. We then parameterized a dynamical model of hosts, parasites, and resources with this foraging function, showing how foraging depression can create a hydra effect. Mathematically, the hydra arose when increased resource productivity exceeded any increase in resource consumption per host. Therefore, the foraging-mediated hydra effect more likely emerged (1) for hosts that strongly control logistic-like resources and (2) during larger epidemics of moderately virulent parasites. We then analyzed epidemics from 13 fungal epidemics in nature. We found evidence for a foraging-mediated hydra effect: large outbreaks depressed foraging rate and correlated with increased densities of both algal resources andDaphniahosts. Therefore, depression of the foraging rate of infected hosts can produce higher host densities even during epidemics of parasites that increase host mortality. Such hydras might prevent the collapse of host populations but also could produce higher densities of infected hosts.