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When less is more: positive population-level effects of mortality
Arne Schröder1, Anieke van Leeuwen2, Tom C Cameron3
1Department 4: Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany.
Trends in Ecology & Evolution
|September 29, 2014
Summary
Mortality can surprisingly boost population density, especially in specific life stages. This effect is best explained by stage-structured models, highlighting the importance of individual variation in ecological theory.
Area of Science:
- Ecology
- Population Dynamics
- Theoretical Ecology
Background:
- Studies indicate that imposing mortality on a population can paradoxically increase the density of certain life-history stages or the total population.
- Understanding these positive population-level effects of mortality is crucial for advancing population, community, and applied ecology.
Purpose of the Study:
- To reconcile existing ecological theory and empirical data regarding the effects of mortality on population density.
- To evaluate the consistency of mathematical models and experimental findings on mortality-induced density changes.
Main Methods:
- Comparative analysis of mathematical models predicting mortality effects.
- Review and synthesis of experimental data demonstrating population responses to mortality.
- Evaluation of stage-structured versus unstructured population models.
Main Results:
- Mathematical models used to study mortality effects yield varied predictions and proposed mechanisms.
- Experimental studies predominantly show stage-specific increases in density following mortality imposition.
- Empirical evidence aligns with theories based on stage-structured population models, but not unstructured ones.
Conclusions:
- Stage-specific positive effects of mortality on population density are likely prevalent in natural systems.
- Ecological theory development necessitates the inclusion of within-population individual variation.
- Stage-structured population models provide a more accurate framework for understanding these phenomena.
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