Identifying mechanistic models of spatial behavior using pattern-based modeling: An example from lizard home ranges

Landscape and population level patterns form through the aggregation of responses of individual organisms to heterogeneity. Spatial organization within a population can range from random overlap of individual home ranges, to completely exclusive territories, with most populations falling somewhere between these two extremes. A fundamental question in behavioral ecology concerns the factors that influence the degree of spatial overlap of home ranges, and the processes that determine how likely it is that an individual will access resources over its home range. However, traditional experimental methods are not always practical or possible. Pattern-based modeling is an alternative, non-intrusive technique for explaining observed patterns. We explored behavioral mechanisms for home range overlap in a Scincid lizard, Tiliqua rugosa, by constructing a spatially explicit individual based model. We tested two mechanisms, one that used refuge sites randomly and one that included a behavioral component. The random use model, the fixed total range model, incorporated all refuge sites within a circle of radius h. The behavioral model, the variable total range model, probabilistically incorporated refuge sites based on nearest neighbor distances and use by conspecifics. Comparisons between the simulated patterns and the observed patterns of range overlap provided evidence that the variable total range model was a better approximation of lizard space use than the fixed total range model. Pattern-based modeling showed substantial promise as a means for identifying behavioral mechanisms underlying observed patterns.