Predators with multiple ontogenetic niche shifts have limited potential for population growth and top-down control of their prey
2013 (English)In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 182, no 1, 53-66 p.Article in journal (Refereed) Published
Catastrophic collapses of top predators have revealed trophic cascades and community structuring by top-down control. When populations fail to recover after a collapse, this may indicate alternative stable states in the system. Overfishing has caused several of the most compelling cases of these dynamics, and in particular Atlantic cod stocks exemplify such lack of recovery. Often, competition between prey species and juvenile predators is hypothesized to explain the lack of recovery of predator populations. The predator is then considered to compete with its prey for one resource when small and to subsequently shift to piscivory. Yet predator life history is often more complex than that, including multiple ontogenetic diet shifts. Here we show that no alternative stable states occur when predators in an intermediate life stage feed on an additional resource (exclusive to the predator) before switching to piscivory, because predation and competition between prey and predator do not simultaneously structure community dynamics. We find top-down control by the predator only when there is no feedback from predator foraging on the additional resource. Otherwise, the predator population dynamics are governed by a bottleneck in individual growth occurring in the intermediate life stage. Therefore, additional resources for predators may be beneficial or detrimental for predator population growth and strongly influence the potential for top-down community control.
Place, publisher, year, edition, pages
University of Chicago Press, 2013. Vol. 182, no 1, 53-66 p.
ontogenetic niche shifts, life-cycle complexity, mixed interactions, predator-prey dynamics, Gadus morhua, size-structured population
IdentifiersURN: urn:nbn:se:umu:diva-78947DOI: 10.1086/670614ISI: 000320587300007OAI: oai:DiVA.org:umu-78947DiVA: diva2:638268
This study is part of the PLAN FISH project, financially supported by the Swedish Environmental Protection Agency and the Swedish Board of Fisheries.2013-07-292013-07-292014-02-07Bibliographically approved