This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2025. The fellowship supports research and training of the fellow that will contribute to biology in innovative ways. Behavior is one of the most flexible traits that an animal (or human) can use to help it survive and thrive. But this flexibility can also make behavior challenging to study, especially across levels of biological organization. This project investigates both behavior and the genes that are actively being used in the brain to generate that behavior in three ways. First, how do behavior and brain gene expression change across the lifetime of an animal? Second, how do the brain and the body work together to produce a behavior? And third, how do behavior and brain gene expression change based on what the animal functionally needs to accomplish? Together, what we learn from these aims will enhance our understanding of how brains, bodies, and behaviors function together. To achieve the above aims, this project will use diverse molecular techniques and a study organism that undergoes major changes in development, develops alternative morphologies and behaviors based on the environment, and displays biparental care: the bull-headed dung beetle, Onthophagus taurus. In this species, high-nutrition males develop into large, horned “fighters” whereas low-nutrition males develop into small, hornless “sneakers.” In contrast, females develop the same range of body sizes but never grow horns and ar