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Predator life history affects persistence times of predators and consumers in an intraguild predation system
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, The Netherlands.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Complex habitats and thereby weaker predator-prey interactions have been suggested to promote coexistence between predator and prey in intraguild predation (IGP) systems. For a size-structured IGP system spatial refuges have been shown to weaken interactions but not to promote coexistence. Spatial refuges however also affect the spatial distribution of small and large individuals. Here we report the results of a multi-generation laboratory experiment where we manipulated interaction strength by using the same IG predator (Common guppy, Poecilia reticulata) but a population with a different life-history evolution and lower predation voracity. Resident IG prey (Least Killifish, Heterandria formosa) were invaded by large or small IG predators, invasion success was recorded. Compared to the invasion by more voracious IG predator individuals, weaker predation per se (no refuges) did not affect invasion success but did increase IG prey and IG predator persistence times. Compared to the invasion by more voracious IG predator individuals in the presence of refuges, weaker predation per se (no refuges) resulted in similar persistence times but different invasion success.  We conclude that the effect on community dynamics depends on the context in which weak interactions are realized. Both spatial refuges and life-history differences affected predation strength and competitive relationships quantitatively but only when spatial refuges were present was this quantitative change coupled to qualitative changes in species interactions. Though under stable environmental conditions in our experiment coexistence did not occur we argue that in temporarily or spatially variable systems weak interactions have the potential to promote coexistence by prolonging IG predator and IG prey persistence times.

Keyword [en]
indirect effects, interaction strength, mixed predation-competition, multi-generation, trait variation
National Category
Ecology
Identifiers
URN: urn:nbn:se:umu:diva-107024OAI: oai:DiVA.org:umu-107024DiVA: diva2:846473
Available from: 2015-08-17 Created: 2015-08-17 Last updated: 2015-09-02
In thesis
1. Ontogenetic bottlenecks: effects on intraguild predation systems and ecosystem efficiency
Open this publication in new window or tab >>Ontogenetic bottlenecks: effects on intraguild predation systems and ecosystem efficiency
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Size-dependent differences between individuals in size-structured organisms have fundamental effect on population and community dynamics. Intraguild predation (IGP) is one specifically interesting constellation that often arises when two size-structured populations interact. Ontogenetic bottlenecks that determine population size-structure are affected by both population intrinsic as well as population extrinsic factors, and are therefore context-dependent. Surprisingly, size-structured IGP systems have mainly been investigated theoretically and especially long-term empirical studies are widely lacking. In this thesis I investigate empirically how habitat complexity, interaction strength, and stage-specific resource availabilities affect population processes and their effects on the dynamics of a size-structured IGP system. I conducted multi-generation experiments in a size-structured IGP system, with the Least Killifish (Heterandria formosa) as IG prey and the Common Guppy (Poecilia reticulata) as IG predator. With no alternative resource next to the shared resource, IG predator and IG prey could not coexist. Weak interactions only increased IG prey and IG predator persistence times and observed exclusion patterns depended on habitat complexity. An alternative resource for either the juvenile IG predator or the juvenile IG prey on the other hand promoted coexistence. However, this coexistence was context-dependent. Ontogenetic bottlenecks played a central role in the dynamics of the size-structured IGP system in general. In the final study I show that an ontogenetic bottleneck can, through changes in stage-specific resource availabilities, be affected in a way that leads to increased trophic transfer efficiency with potential effects on higher trophic levels.

Overall, the results emphasize importance of the broader context in which size-structured communities are embedded. Especially, when managing natural communities it is important to account for the combined effects of size-structure, stage-specific resource availabilities, and habitat structure. Specifically, when managing species that connect habitats or ecosystems all life-stages’ environmental conditions must be consider in order to ensure strong predictive power of tools used for ecosystem management planning.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2015. 29 p.
Keyword
mixed interactions, cannibalism, life-history omnivory, ontogenetic niche shift, biomass overcompensation, biomass production, ontogenetic asymmetry, indirect effects
National Category
Ecology
Research subject
biology; Animal Ecology
Identifiers
urn:nbn:se:umu:diva-105759 (URN)978-91-7601-299-4 (ISBN)
Public defence
2015-09-25, Lilla hörsalen (KB3A9), KBC-huset, Linnaeus väg 6, Umeå, 14:00 (English)
Opponent
Supervisors
Available from: 2015-09-04 Created: 2015-06-29 Last updated: 2015-09-02Bibliographically approved

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Reichstein, BirtePersson, Lennart

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