Abstract: Species interactions have a profound influence on the ecological and evolutionary dynamics of communities, with critical implications for ecosystem function. Given that species and interactions are being lost at alarming rates, it is imperative to understand how communities assemble if we are to prevent their collapse and restore lost interactions. A community's ability to resist collapse in the face of global change and extinction depends on the structure of interactions across species; however, little is known about how different interaction patterns assemble over contemporary and historic time scales. We explore the ecological and evolutionary forces shaping interactions across a temporal gradient of plant-pollinator interaction networks in restorations in the Central Valley of California, and across a spatial gradient in the Madrean Sky Islands. In the former we find that species occupy highly dynamic network positions through time, causing the assembly process to be punctuated by major network reorganizations. The sky islands represent replicate plant-pollinator communities with varying assembly histories structured by the distance from source populations. We plan to explore how network roles relate to plant and pollinator fitness, and how these roles are shaped by the current ecological context and past evolutionary history. This work will bring new insights into how communities form, evolve, and persist through time.