The long-term objective of this research project is to identify the interactions among chemical messengers that control behaviors. Neuropeptides regulate social behaviors in representative species from all vertebrate classes. Species differences in behavior, however, have made development of clear mechanistic models difficult. This project investigates the complexity of behavioral mechanisms using a combination of animal experiments and computational models. Field and laboratory studies will be combined to address important emerging questions on neuropeptide modulation of male vertebrate behaviors. The agent-based modeling approach is especially well-suited to address this problem. Synthetic experiments with the model allow for exploration of conditions impractical or impossible in empirical tests. The model is expected to propose novel mechanisms underlying neuropeptide control of behavior. This project thus implements a tightly controlled experiment-model-experiment loop and develops a new paradigm for a systems biology approach towards understanding social behavior. Neuropeptides alter a variety of vertebrate social behaviors, including parental, aggressive, and reproductive behaviors. Conserved behaviors and chemical messengers will make the empirical results and the model broadly applicable to vertebrates. Results will significantly advance our understanding of the effect of neuropeptides on vertebrate behavioral plasticity. This project also includes a significant training component, with involvement of an undergraduate field biology class (with a 30% minority makeup) and training of graduate students in a unique inter-disciplinary environment. The data management plan includes deposition of new software at SourceForge and archiving of digital data in the PI's institutional databases.