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Inherent demographic stability in mutualist-resource-exploiter interactions.
1Department of Biology, Duke University, Durham, North Carolina 27708.
The American Naturalist
|March 27, 2015
Summary
Ecological theory suggests mutualisms are unstable, but this study shows indirect interactions can stabilize them. Demography-mediated coexistence between mutualists and exploiters prevents extinction and stabilizes populations.
Area of Science:
- Ecology
- Population Dynamics
- Theoretical Ecology
Background:
- Mutualisms are theoretically unstable due to positive feedback and competitive exclusion by exploiters.
- Existing stabilizing mechanisms often require additional factors or features.
- The stability of many mutualistic interactions in nature remains unexplained by current theory.
Purpose of the Study:
- To investigate how demography-mediated interactions influence the coexistence of mutualists and exploiters.
- To determine if indirect ecological interactions can stabilize mutualistic systems.
- To provide a unified explanation for the observed stability of mutualism across diverse systems.
Main Methods:
- Employed an explicitly demographic approach to model interactions.
- Analyzed indirect, demography-mediated interactions between mutualists and exploiters.
- Considered distinct resource demographic responses to mutualistic and exploitative partners.
Main Results:
- Indirect demographic interactions facilitate mutualist-exploiter coexistence.
- Coexistence stabilizes the population abundances of mutualists, exploiters, and their shared resources.
- This mechanism operates across both long-lasting (e.g., protection mutualisms) and short-lived (e.g., pollination) interactions.
Conclusions:
- Demography-mediated interactions offer a single, unifying explanation for mutualism stability.
- The key factor, demographic responses to interspecific interaction, is common in nature.
- The model's requirement for demographic structure, often generated by interspecific interactions, is also widespread.
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