Associate Professor New Jersey Institute of Technology, United States
Background/Question/Methods
Several army ant and army ant-like species in the Formicidae family exhibit notable behavioral and reproductive traits that most other ant species do not. Specifically, these army ant colonies alternate between brood care and reproductive phases in a highly regimented manner. Existing theoretical models support a hypothesis that cyclic reproduction is favored under a “high cost of entry” scenario, that is, when foraging costs increase faster for a smaller number of larvae. However, a detailed understanding of the adaptive significance of this cyclic reproductive behavior is lacking. In particular, it is still a question as to how this evolutionary pressure selects for colony regulation mechanisms that give rise to strict reproductive cycles. The work presented here seeks to address this question from a mathematical modeling perspective.
Results/Conclusions
In this work, we develop a novel mathematical model that links population growth, ant reproductive stages, and foraging costs with colony fitness. Our model is flexible in the sense that it is valid for varying degrees of temporal reproductive fluctuations ranging from continuous reproduction to highly cyclic reproduction. Optimization of certain model parameters with respect to colony fitness during simulations under varying foraging cost/impact scenarios results in the “selection” of a particular reproductive strategy. For example, when larval survival increases nonlinearly with the foraging output of the colony, then simulations produce strict reproductive cycles. The results of our modeling and simulation help to clarify the adaptive significance of army ant reproductive cycles. Further, our modeling framework has the potential to be linked with genetic studies to support enhanced synthesis of theory and experiment.
