95th ESA Annual Meeting (August 1 -- 6, 2010)

COS 79-7 - Critical scales of heterogeneity: unraveling the relationship between group behavior, home range size, and resource dispersion

Thursday, August 5, 2010: 10:10 AM
333, David L Lawrence Convention Center
Christopher X. J. Jensen, Science and Mathematics, Pratt Institute, Brooklyn, NY, Jennifer L. Verdolin, NESCent (National Evolutionary Synthesis Center, Durham, NC, Dylan Moore, Department of Digital Arts, Pratt Institute, Brooklyn, NY and Aaron Cohen, Digital Arts, Pratt Institute, Brooklyn, NY

All measures of heterogeneity are scale-dependent. For example, an environment experienced by a widely-ranging species as homogenous can appear highly heterogeneous to species with a more limited home range. The scale-dependent properties of heterogeneity are rarely accounted for and can vary significantly among species. The goal of the present study was to understand how previously-demonstrated relationships between group size and resource dispersion are influenced by the scale at which heterogeneity is measured. Using fieldTest, an individual-based model designed to simulate the social behavior of group-territorial species, we explored how well group size is predicted by resource heterogeneity measured at multiple scales. Individual home range was manipulated in order to understand the degree to which the most predictive scale of heterogeneity is influenced by individual rather than group properties.

Previous work using fieldTest has demonstrated that increased resource heterogeneity results in larger group sizes. In this study, we manipulated home range size and identified the scale at which heterogeneity best predicts group size. Overall, we found that the relationship between heterogeneity and group size is dependent to a large extent on the home range size of individuals. Simulations performed at various home range sizes demonstrated that within limits, the scale of heterogeneity that best predicts group size will depend on how widely each individual ventures. However, emergent group properties provide a feedback that influences the scales at which heterogeneity successfully predicts group size. This suggests that individual behaviors alone are insufficient to explain the relationship between group size and resource dispersion.