Impact of Intraguild Predation and Stage Structure on Simple Communities along a Productivity Gradient

Abstract

Impact of intraguild predation and stage structure on simple communities along a productivity gradient Mylius, S.D.; Klumpers, K.; de Roos, A.M.; Persson, L. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. abstract: We analyze the consequences of intraguild predation and stage structure for the possible composition of a three-species community consisting of resource, consumer, and predator. Intraguild predation, a special case of omnivory, induces two major differences with traditional linear food chain models: the potential for the occurrence of two alternative stable equilibria at intermediate levels of resource productivity and the extinction of the consumer at high productivities. At low productivities, the consumer dominates, while at intermediate productivities, the predator and the consumer can coexist. The qualitative behavior of the model is robust against addition of an invulnerable size class for the consumer population and against addition of an initial, nonpredatory stage for the predator population, which means that the addition of stage structure does not change the pattern. Unless the top predator is substantially less efficient on the bottom resource, it tends to drive the intermediate species extinct over a surprisingly large range of productivities, thus making coexistence generally impossible. These theoretical results indicate that the conditions for stable food chains involving intraguild predation cannot involve strong competition for the bottommost resource.

The mixotroph Ochromonas tuberculata may invade and suppress specialist phago- and phototroph plankton communities depending on nutrient conditions

“…The HNF formed an intermediate prey in the heterotrophic food chain (bacteria/picophytoplankton-HNF-ciliates) and furthermore competed with O. tuberculata for bacteria and picophytoplankton. The reduction of B. saltans is consistent with the expectation that an omnivorous top consumer (i.e., here the ciliate) reduces its intermediate prey (e.g., Diehl and Feissel 2000;Mylius et al 2001) by feeding simultaneously on the intermediate prey and on the common basal resource ("strategy of eating your competitor"; Thingstad et al 1996). It is also consistent with the results of Rothhaupt (1996b) who showed that O. tuberculata eventually outcompetes B. saltans once the bacterial prey has been grazed down to a density that limits the growth of the HNF.…”

Adaptive behaviour, tri-trophic food-web stability and damping of chaos

“…The above equation is our second assumption and has been recognized as a general feature promoting the existence of intra-guild predation as a feasible trophic mode [14,36,37]. Notice how this assumption can be linked to the concept of 'trophic upgrading' [38], namely the feasibility of omnivory as a trophic mode is assured provided that the net trophic efficiency to the omnivore via intraguild predation exceeds that of feeding on the resource directly.…”

Prey-mediated avoidance of an intraguild predator by its intraguild prey

“…Models suggest that IG predation should be rare (Holt and Polis 1997;Mylius et al 2001), yet it is frequently documented in natural systems (Palomares and Caro 1999;Donadio and Buskirk 2006). However, these models fail to account for individual antipredator behavior that could lead to Communicated by Janne Sundell.…”