Patterns of exclusion in an intraguild predator–prey system depend on initial conditions


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  • 1When intraguild (IG)-prey are superior to IG-predators in competing for a shared resource, theory predicts coexistence of the IG-prey or the IG-predator with the resource depending on the productivity level: (a) resource and IG prey coexist when productivity is low; (b) IG-predator and resource coexist at high productivity; (c) if IG-prey and IG-predators can coexist, it is only at intermediate productivity levels.
  • 2We tested the existence of productivity-dependent regions of coexistence using an experimental system of two predatory mites and a shared food source (pollen).
  • 3At high levels of pollen supply (i.e. high productivity), the IG-predator excluded the IG-prey in most, but not all, cases. The same pattern of exclusion was observed at low productivity, at which the IG-prey was expected to exclude the IG-predator. Therefore, species composition could not be predicted by productivity levels. Instead, our results show that initial conditions affected strongly the outcome of the interaction.
  • 4We emphasize the need for theory on IG-predation that takes the effects of stage structure, initial conditions and transient dynamics into account.