Contrasting a System Dynamics Model and an Agent-Based Model of Food Web Evolution

An agent-based model of food web evolution is presented and contrasted with a particular system dynamics model. Both models examine the effects of speciation and species invasion of food webs, but the agent-based approach focuses on the interactions between individuals in the food web, whereas the system dynamics approach focuses on the overall system dynamics. The system dynamics model is an abstract model of species co-evolution that shows similar characteristics to many natural food webs. The agent-based model attempts to model a similarly abstract food web (in which species are characterised by abstract features that determine how they will fare against any other species). The ultimate aim of this exercise is to explore the many of the assumptions inherent in the system dynamics model; the current challenge is to simply replicate the system dynamics results using agent-based modelling. Preliminary studies have revealed some underlying assumptions in the system dynamics model, as well as some intrinsic difficulties in linking the two different approaches. The paper discusses the key difficulties in linking these different types of models, and presents some discussion of the limits and benefits benefits that each approach may bring to the analysis of the problem.