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Overcompensation and population cycles in an ungulate
B T Grenfell1, O F Price, S D Albon
1Zoology Department, University of Cambridge, UK.
Nature
|February 27, 1992
Summary
Highly overcompensating density-dependent mortality can cause recurrent population crashes in vertebrates. This mechanism, rarely considered for vertebrates, explains observed population fluctuations in Soay sheep.
Area of Science:
- Ecology
- Population Dynamics
- Vertebrate Zoology
Background:
- Theoretical models suggest overcompensatory density-dependence can cause population fluctuations.
- Invertebrate population models often lack sufficient overcompensation for sustained cycles.
- Overcompensation's role in vertebrate population cycles remains under-explored.
Purpose of the Study:
- To investigate if overcompensatory density-dependent mortality can generate population cycles in vertebrates.
- To explain recurrent population crashes observed in Soay sheep populations.
Main Methods:
- Analysis of density-dependent mortality patterns.
- Modeling of population dynamics with strong overcompensation.
Main Results:
- Highly overcompensating density-dependent mortality can generate recurrent population crashes.
- Observed crashes in Soay sheep align with this overcompensatory mortality model.
- Mortality is sharply focused within a narrow population density range.
Conclusions:
- Overcompensation is a viable mechanism for generating population cycles in vertebrates.
- This mechanism explains the observed crash intervals in Soay sheep populations.
- Understanding density-dependent mortality is crucial for vertebrate population management.
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