Ant colonies have a striking division of labor: queens lay eggs, while workers, unable to reproduce, perform tasks such as brood care, foraging and defense. The task a worker performs depends on its size, age and experience. How is task performance in ants controlled by a tiny amount of nerve tissue, the brain? The goal of the project is to discover how differences in the brains of worker ants in a colony control task performance, and how the ecology of a species may influence worker brain structure and behavior. Ants may change tasks as they age, beginning as nurses and ending as foragers. Their brains need to be plastic so that they can generate age-appropriate behavior. In some species, workers show specialized behaviors, such as defending the colony, and are equipped with large and powerful jaws that make them effective soldiers. If workers are specialized for defense, their brains must respond to stimuli associated with threats to the colony and control aggressive behavior. Thus the brain of a nurse should respond only to the needs of brood and the brain of a defender should respond to threats from enemies. The project will analyze ant social behavior and examine age- and task-specific differences in the size of worker brains, brain compartments and individual nerve cells as well as the chemical composition of the brains of workers of different species in an extremely diverse group of ants. The expected subtle brain differences will help to understand how slight changes in brain structure and function can result in pronounced behavioral differences and how behavior develops during maturation. The project will train graduate and undergraduate students (including minority students) in behavioral, anatomical, neurobiological and molecular techniques and enrich the education of K-12 students by introducing them to behavior, neuroscience, ecology and evolution.