Intra-guild predation (IGP) can increase or decrease prey density depending on the strength of IGP.

Autor: Chang FH; School for Environment and Sustainability, University of Michigan, 440 Church Street, Ann Arbor, Michigan, USA., Cardinale BJ; School for Environment and Sustainability, University of Michigan, 440 Church Street, Ann Arbor, Michigan, USA.; Cooperative Institute for Great Lakes Research (CIGLR), School for Environment and Sustainability, University of Michigan, 440 Church Street, Ann Arbor, Michigan, USA.
Jazyk: angličtina
Zdroj: Ecology [Ecology] 2020 Jul; Vol. 101 (7), pp. e03012. Date of Electronic Publication: 2020 May 15.
DOI: 10.1002/ecy.3012
Abstrakt: In consumer communities, intra-guild predation (IGP) is a commonly observed interaction that is widely believed to increase resource density. However, some recent theoretical work predicts that resource density should first decrease, and then increase as the strength of IGP increases. This occurs because weak to intermediate IGP increases the IG predator density more than it reduces the IG prey density, so that weak to intermediate IGP leads to the lowest resource density compared to weak or strong IGP. We test this prediction that basal resource density would first decrease and then increase as the strength of IGP increase. We used a well-studied system with two protozoa species engaged in IGP and three bacteria species as the basal resources. We experimentally manipulated the percentage of the IG prey population that was available to an IG predator as a proxy for IGP strength. We found that bacterial density first decreased (by ~25%) and then increased (by ~30%) as the strength of IGP increased. Using a modified version of a published IGP model, we were able to explain ~70% of the variation in protozoa and bacterial density. Agreement of the empirical results with model predictions suggests that IGP first increased the IG predator density by consuming a small proportion of the IG prey population, which in turn increased the summed consumer density and decreased the bacterial resource density. As IGP strength increased further, the IG predator became satiated by the IG prey, which then freed the bacterial resource from predation and thus increased bacterial density. Consequently, our work shows that IGP can indeed decrease or increase basal resource density depending on its strength. Consequently, the impacts of IGP on resource density is potentially more complex than previously thought.
(© 2020 by the Ecological Society of America.)
Databáze: MEDLINE
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