Several decades of dynamical analyses of food-web networks have led to important insights into the effects of complexity, omnivory and interaction strength on food-web stability. Several recent insights are based on nonlinear bioenergetic consumer-resource models that display chaotic behavior in three species food chains which can be stabilized by omnivory and weak interaction of a fourth species. We slightly relax feeding on low-density prey in these models by modifying standard food-web interactions known as "type II" functional responses. This change drastically alters the dynamics of realistic systems containing up to ten species. Our modification stabilizes chaotic dynamics in three species systems and reduces or eliminates extinctions and non-persistent chaos in ten species systems. This increased stability allows analysis of systems with greater biodiversity than in earlier work and suggests that dynamic stability is not as severe a constraint on the structure of large food webs as previously thought. The sensitivity of dynamical models to small changes in the predator-prey functional response well within the range of what is empirically observed suggests that functional response is a crucial aspect of species interactions that must be more precisely addressed in empirical studies.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics