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. The research focuses on gall wasps-- tiny insects that form protective growths, or galls, on oak trees. These wasps often specialize on particular oak species, but when related oak species hybridize (interbreed), the new, hybrid trees may provide opportunities for wasps to shift from one parent oak species to the other by using the hybrid trees as a “bridge”. The study of hybridization is gaining importance as species introductions and range shifts increase opportunities for species to interbreed that would otherwise remain isolated. Clarifying how hybridization in plants can affect insect diversity may be crucial, therefore, for understanding the great biodiversity of insects that is observed today. These findings will contribute to our understanding of how biodiversity is generated and maintained, particularly in the face of environmental change. Furthermore, the fellow will leverage their experiences working at a federal agency (U.S. Geological Survey) to create resources for students interested in pursuing a career in the federal government. Hybridization plays an important role in generating and maintaining biodiversity, particularly in plants. The hybrid bridge hypothesis posits that hybridization in plant hosts can facilitate host shifts in associated insect parasites. If hy