Reproductive interactions among species represent a powerful evolutionary force driving diversification, particularly when organisms interact with a mosaic of other taxa across their geographic distribution. Theory predicts that spatial variation in community structure can lead to divergent selection on reproductive behaviors across geography, when different phenotypes are
favored in different species assemblages. A critical outcome of this diversifying selection is the evolution of reproductive isolation across conspecific populations, as male signals differentiate and females evolve preferences for local signals. Thus, species mosaics provide a key opportunity to
investigate the direct and indirect effects of reinforcement in contact zones. In this seminar, I will present recent work on chorus frogs (Pseudacris) illustrating how interactions between species via reinforcement not only lead to increased isolation between species but also indirectly promote the evolution of reproductive isolation within species, potentially initiating a cascade of speciation events.