Emergent Allee effects in top predators feeding on structured prey populations
- 22 March 2003
- journal article
- Published by The Royal Society in Proceedings Of The Royal Society B-Biological Sciences
- Vol. 270 (1515), 611-618
- https://doi.org/10.1098/rspb.2002.2286
Abstract
Top predators that forage in a purely exploitative manner on smaller stages of a size–structured prey population have been shown to exhibit an Allee effect. This Allee effect emerges from the changes that predators induce in the prey–population size distribution and represents a feedback of predator density on its own performance, in which the feedback operates through and is modified by the life history of the prey. We demonstrate that these emergent Allee effects will occur only if the prey, in the absence of predators, is regulated by density dependence in development through one of its juvenile stages, as opposed to regulation through adult fecundity. In particular, for an emergent Allee effect to occur, over–compensation is required in the maturation rate out of the regulating juvenile stage, such that a decrease in juvenile density will increase the total maturation rate to larger/older stages. If this condition is satisfied, predators with negative size selection, which forage on small prey, exhibit an emergent Allee effect, as do predators with positive size selection, which forage on large adult prey. By contrast, predators that forage on juveniles in the regulating stage never exhibit emergent Allee effects. We conclude that the basic life–history characteristics of many species make them prone to exhibiting emergent Allee effects, resulting in an increased likelihood that communities possess alternative stable states or exhibit catastrophic shifts in structure and dynamics.Keywords
This publication has 24 references indexed in Scilit:
- Size-dependent life-history traits promote catastrophic collapses of top predatorsProceedings of the National Academy of Sciences, 2002
- Effects of Enrichment on Three‐Level Food Chains with OmnivoryThe American Naturalist, 2000
- Food Web Effects of Prey Size Refugia: Variable Interactions and Alternative Stable EquilibriaThe American Naturalist, 1999
- A Theoretical Framework for Intraguild PredationThe American Naturalist, 1997
- Effects of Food Web Compensation After Manipulation of Rainbow Trout in an Oligotrophic LakeEcology, 1995
- Morphological constraints in the piscivore‐planktivore interaction: Implications for the trophic cascade hypothesisLimnology and Oceanography, 1994
- Rehabilitation of a Stunted Population of Arctic Char by Intensive FishingNorth American Journal of Fisheries Management, 1993
- Changes in the Composition and Standing Crop of Salt-Marsh Communities in Response to the Removal of a GrazerJournal of Ecology, 1986
- The Size-Efficiency Hypothesis and the Size Structure of Zooplankton CommunitiesAnnual Review of Ecology and Systematics, 1976
- Predation, Body Size, and Composition of PlanktonScience, 1965