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Weak interactions, omnivory and emergent food-web properties
Mark Emmerson1, Jon M Yearsley
1Department of Zoology, Ecology and Plant Sciences, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland. m.emmerson@ucc.ie
Proceedings. Biological Sciences
|April 23, 2004
Summary
Real ecosystems favor weak species interactions. This study reveals that a skew towards weak interactions enhances community stability, but only when omnivory is present, impacting ecosystem recovery.
Area of Science:
- Ecology
- Theoretical Ecology
- Community Ecology
Background:
- Empirical data show species interaction strengths are typically skewed towards weak links in real ecosystems.
- Theoretical models often use uniform interaction strengths, deviating from natural distributions.
- Weak interactions, particularly in omnivory, are hypothesized to be crucial for community stability.
Purpose of the Study:
- To investigate how interaction-strength distributions affect community stability metrics (return time, permanence, feasibility).
- To explore the relationship between interaction-strength distribution, omnivory, and community dynamics.
- To compare theoretical findings with empirical observations of ecosystem stability.
Main Methods:
- Utilized simple Lotka-Volterra models to simulate ecological communities.
- Analyzed the impact of skewed versus uniform interaction-strength distributions.
- Examined community properties like return time, permanence, and feasibility.
Main Results:
- A skew towards weak interactions promotes stability only in the presence of omnivory.
- Skewed interaction strengths emerge as a property of stable omnivorous communities.
- While promoting stability, weak interactions can increase return times and delay ecosystem recovery.
Conclusions:
- The distribution of interaction strengths significantly influences community stability and dynamics.
- Omnivory plays a critical role in how interaction-strength distributions affect ecosystem stability.
- Findings reconcile theoretical models with empirical observations, offering insights into community assembly.