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Competitive intransitivity promotes species coexistence
Robert A Laird1, Brandon S Schamp
1Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada. rlaird@ucalgary.edu
The American Naturalist
|July 29, 2006
Summary
Increased competitive intransitivity, or nonhierarchical competition, promotes species coexistence in simulated communities. Even moderate levels enhance biodiversity by delaying competitive exclusion and maintaining more species over time.
Area of Science:
- Ecology
- Theoretical Ecology
- Biodiversity Research
Background:
- Species coexistence is fundamental to biodiversity.
- Competitive interactions are key drivers of community structure.
- The role of nonhierarchical competition (intransitivity) in maintaining diversity is an active area of research.
Purpose of the Study:
- To investigate how varying levels of competitive intransitivity influence species coexistence.
- To determine if intransitivity can promote biodiversity in ecological communities.
Main Methods:
- Utilized a spatially explicit cellular automaton model.
- Simulated local competition with different degrees of intransitivity.
- Tracked species persistence and competitive exclusion over 500 generations.
Main Results:
- Higher levels of intransitivity generally led to more sustained species coexistence.
- Increased intransitivity resulted in a more unpredictable competitive outcome.
- Moderate intransitivity significantly extended the time to first competitive exclusion and increased species numbers.
Conclusions:
- Modest levels of competitive intransitivity can promote community-scale biodiversity.
- Intransitivity may be a crucial mechanism for ecological equivalence, linking to neutral theory.
- Findings have implications for understanding plant community dynamics and biodiversity maintenance.