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Host-Manipulation by Trophically Transmitted Parasites: The Switcher-Paradigm
Ryosuke Iritani1, Takuya Sato2
1Biosciences, College of Life and Environmental Science, University of Exeter, Cornwall Campus, Penryn, Cornwall TR10 9EZ, UK; Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
Trends in Parasitology
|September 30, 2018
Summary
Parasites manipulate hosts, increasing predation. A new switcher-paradigm shows how parasite-driven suppression followed by enhancement can ensure parasite survival and stable predator-prey dynamics.
Area of Science:
- Ecology
- Parasitology
- Evolutionary Biology
Background:
- Trophically transmitted parasites often manipulate intermediate hosts to increase predation by definitive hosts (enhancement).
- Ecological theory suggests enhancement can destabilize predator-prey ratios, potentially leading to host and parasite extinction.
- The persistence of enhancement in nature presents a paradox given these theoretical predictions.
Purpose of the Study:
- To resolve the paradox of how parasite-mediated enhancement persists despite theoretical instability.
- To introduce and conceptualize the 'switcher-paradigm' for understanding host-parasite dynamics.
- To explore how sequential phases of predation suppression and enhancement influence parasite persistence.
Main Methods:
- Development of theoretical models incorporating sequential phases of host predation.
- Analysis of predator-prey ratio dynamics under the proposed switcher-paradigm.
- Conceptual framework linking within-host to community-level ecological processes.
Main Results:
- Theoretical models indicate that switching from suppression to enhancement phases can increase parasite persistence.
- In certain scenarios, the switcher-paradigm can counteract strong enhancement effects, stabilizing predator-prey ratios.
- The framework suggests that sequential predation dynamics are crucial for parasite survival.
Conclusions:
- The switcher-paradigm offers a novel explanation for the persistence of host-manipulation and enhancement in natural systems.
- Sequential predation dynamics, including suppression and enhancement, are key to understanding host-parasite ecological stability.
- This framework bridges ecological scales, from individual host-parasite interactions to community-level dynamics.
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