The impact of mortality on predator population size and stability in systems with stage-structured prey

Abrams, Peter A. and Quince, Christopher (2005) The impact of mortality on predator population size and stability in systems with stage-structured prey. Theoretical Population Biology, 68 (4). pp. 253-266. ISSN 0040-5809

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The relationships between a predator population's mortality rate and its population size and stability are investigated for several simple predator-prey models with stage-structured prey populations. Several alternative models are considered; these differ in their assumptions about the nature of density dependence in the prey's population growth; the nature of stage-transitions; and the stage-selectivity of the predator. Instability occurs at high, rather than low predator mortality rates in most models with highly stage-selective predation; this is the opposite of the effect of mortality on stability in models with homogeneous prey populations. Stage-selective predation also increases the range of parameters that lead to a stable equilibrium. The results suggest that it may be common for a stable predator population to increase in abundance as its own mortality rate increases in stable systems, provided that the predator has a saturating functional response. Sufficiently strong density dependence in the prey generally reverses this outcome, and results in a decrease in predator population size with increasing predator mortality rate. Stability is decreased when the juvenile stage has a fixed duration, but population increases with increasing mortality are still observed in large areas of stable parameter space. This raises two coupled questions which are as yet unanswered; (1) do such increases in population size with higher mortality actually occur in nature; and (2) if not, what prevents them from occurring? Stage-structured prey and stage-related predation can also reverse the 'paradox of enrichment', leading to stability rather than instability when prey growth is increased.

Item Type: Article
Additional Information: Funding Information: The authors thank the Natural Sciences and Engineering Research Council of Canada for financial support, J.M. Biernaskie and three anonymous reviewers for comments on a previous draft of the manuscript, and H. Matsuda for helpful discussions of this topic.
Uncontrolled Keywords: hydra effect,limit cycles,predation,predator-prey models,stability,stage structure,ecology, evolution, behavior and systematics ,/dk/atira/pure/subjectarea/asjc/1100/1105
Faculty \ School: Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 12 Sep 2022 11:31
Last Modified: 21 Oct 2022 01:40
DOI: 10.1016/j.tpb.2005.05.004

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