Document: STE-3-26-1

Concepts from complex adaptive systems as a framework for individual-based modeling.

RAILSBACK, S.F.*

Lang, Railsback & Associates, Arcata, CA, USA ¹

Abstract:
The practice of building and using individual-based ecological models (IBMs) suffers from the lack of modeling theory or conceptual frameworks. We lack even a list of issues to consider in designing models. This lack likely results from ecologists having little experience observing ecosystem behavior as the direct consequence of the characteristics and actions of individuals. The new science of Complex Adaptive Systems (CAS) has focused on how characteristics of individuals affect system-level behaviors. Issues common in CAS models, including the following five examples, are appealing as a list of concepts to address in building and using IBMs. (1) Adaptation: given a model's scales and objectives, what characteristics of its individuals adapt, how do individuals adapt, and what drives adaptation? (2) Emergence: should important individual or population behaviors be forced by model rules or should they emerge as a consequence of simpler rules and interactions among individuals and the environment? (3) Prediction, which appears necessary for many lifelike behaviors: what factors do individuals predict, and how? (4) Fitness and strategy: successful models result from individuals making decisions to increase some measure of their fitness, with fitness measures varying among alternative strategies; what measures of fitness should individuals try to maximize, and how should they switch among fitness measures? (5) Computer simulation: how do computer implementation methods affect perceived model results and success of the modeling effort?.

Keywords: Individual-based models, complex adaptive systems, ecosystem models, modeling theory

This abstract is being presented at: 9:00 AM in session:
Symposium # 27: Advancing the Individual-Based Modeling Approach: New Tools and Concepts.