Adaptive evolution can shape suites of behavioral traits to a remarkable extent, such that different individuals adopt distinct behavioral strategies to facilitate survival and reproduction.  The resulting strategies must balance trade-offs in time, for animals cannot engage in two separate behaviors simultaneously. Work in the Hoke lab asks to what extent those strategies also reflect mechanistic constraints because they depend on overlapping neural circuitry and shared molecular mechanisms. We relate behavioral diversity in guppies to brain gene expression to ask how modularity, homeostasis, and flexibility shape the way gene networks regulate behavior and hence the patterns of adaptive plasticity and evolution.