The role of predation and competition in a stage-structured intraguild predation system
(English)Manuscript (preprint) (Other academic)
Omnivorous species can simultaneously prey on and compete with other species, a type of interaction referred to as intraguild predation (IGP). Theory predicts that coexistence in IGP systems requires a balance between predation and competition interactions, which occurs when the consumer is a superior resource competitor and resource productivity is restricted to intermediate levels. Mixed competition/predation interactions between a predator and a consumer can, however, also result from ontogenetic niche shifts (life history omnivory). When young, a life history omnivore competes with the species that becomes its prey later in life. Resource competition with superior consumers can hence limit the development of young predators, while adult predators can cultivate a favourable environment for their young by suppressing these consumers. We formulate and analyze a model in which predators interact with consumers and resources through a mixture of basic intraguild predation and life history omnivory. The model predicts increasing coexistence when predators change to life history omnivores. Furthermore, we show that the crucial assumption enabling coexistence in case of basic intraguild predation, that consumers are superior resource competitors, demotes coexistence when predators are life history omnivores. In coexistence community dynamics are shaped primarily by predation with competitive interactions playing a marginal role. As a result, community dynamics in stage-structured IGP systems, in which predators are life history omnivores, largely resemble those of a three-species linear food chain.
IdentifiersURN: urn:nbn:se:umu:diva-33443OAI: oai:DiVA.org:umu-33443DiVA: diva2:312456