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Allometric degree distributions facilitate food-web stability.
Sonja B Otto1, Björn C Rall, Ulrich Brose
1Darmstadt University of Technology, Department of Biology, Schnittspahnstrasse 10, 64287 Darmstadt, Germany. sonotto@bio.tu-darmstadt.de
Nature
|December 22, 2007
Summary
Predator-prey body-mass ratios are key to stable ecosystems. This study reveals specific ratio ranges, a
Area of Science:
- Ecology
- Theoretical Ecology
- Bioenergetics
Background:
- Ecosystems rely on feeding interactions for energy flow and food-web stability, allowing species coexistence.
- Predator-prey body-mass ratios are theorized to be crucial for food-web stability, but the underlying mechanisms remain unclear.
Purpose of the Study:
- To investigate how specific predator-prey body-mass ratios promote stability in three-species food chains using a bioenergetic model.
- To identify the constraints on these stable body-mass ratios, considering energy availability and ecosystem dynamics.
Main Methods:
- Utilized a bioenergetic consumer-resource model to simulate tri-trophic (three-species) food chains.
- Analyzed predator-prey body-mass ratios within the model and compared them to empirical data from five natural food webs.
- Examined randomly rewired food webs to assess the role of body mass and allometric degree distributions.
Main Results:
- Identified a 'persistence domain' of predator-prey body-mass ratios essential for food-chain stability.
- Found that bottom-up energy limits stability when predators are smaller than prey, while enrichment dynamics drive instability when predators are larger.
- Observed that 97% of natural tri-trophic food chains fall within the predicted stable body-mass ratio domain.
- Demonstrated that body mass and allometric degree distributions in natural food webs mediate this stability.
Conclusions:
- Specific predator-prey body-mass ratios are critical for maintaining stable food webs.
- The distribution of body masses and feeding interactions, characterized by allometric degree distributions, significantly contributes to ecosystem stability.
- Simple relationships between species' body masses and feeding interactions can underpin the stability of complex ecological networks.
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