The Effect of Differentiation of Prey Community on Stable Coexistence in a Three-Species Food--Web Model

Food webs with intraguild predation (IGP) are widespread in natural habitats. Their adaptation and resilience behaviour is principal for understanding restructuring of ecological communities. In spite of the importance of IGP food webs their behaviour even for the simplest 3-species systems has not been fully explored. One fundamental question is how an increase of diversity of the lowest trophic level impacts the persistence of higher trophic levels in IGP relationships. We analyze a 3-species food web model with a heterogeneous resources and IGP. The model consists of two predators directly coupled via IGP relation and indirectly via competition for resource. The resource is subdivided into distinct subpopulations. Individuals in the subpopulations are grazed at different rates by the predators. We consider two models: an IGP module with immobilization by the top predator and an IGP module with species turnover. We examine the effect of increasing enrichment and varying immobilization (resource transfer) rate on a stable coexistence of predators and resources. We explore how the predictions from the basic 3-species model are altered when the IGP module is extended to multiple resource subpopulations. We investigate which parameters support a robust coexistence in the IGP system. For the case of multiple subpopulations of the resource we present a numerical comparison of the percentage of food webs with stable coexistence for different dimensionalities of the resource community. At low immobilization (transfer) rates our model predicts a stable 3-species coexistence only for intermediate enrichment meanwhile at high rates a large set of stable equilibrium configurations is found for high enrichment as well.