Ant colonies possess a "societal metabolism," acquiring, transforming, and allocating resources through a network of foragers. Two key resources are food and information, including information about where to find food. Ant foraging- trail networks channel foraging workers to known food resources. We asked the question: Does the ability to utilize and share information scale super-linearly with colony size? To address this question, we studied three sympatric species of Pogonomyrmex in central New Mexico that differ in average colony size: P. rugosus, P.maricopa, and P. desertorum. We hypothesized that 1) across species, recruitment increases with average colony size and 2) within species, recruitment increases with heterogeneity of food distribution. We baited marked colonies with a wide ring of hulled, dyed millet seeds arranged in a set distribution of seed densities differentiated by color. We observed baited colonies for 1 hour periods, tracking the capture of dyed seeds and of native seeds. We generated two computer models: a "null" model that simulates ants foraging with no recruitment and one that “evolves” recruitment behaviors through a simulated selective process (using a genetic algorithm). We compared our field results with our null model using the Kolmogorov-Smirnov test.
Results/Conclusions
Empirical results provide evidence for more recruitment to dense food sources within species. Our genetic algorithm shows positive effects of both colony size and heterogeneity on the evolution of recruiting behavior. We are continuing to compare empirical results with simulations. Our results to date suggest that larger colonies are better able to obtain and exploit information about their environments.
