Freshwater systems and their biodiversity worldwide deliver important services, but are under severe threat from looming global change. One species group of particularly broad ecological and human significance is fishes. Freshwater fishes often exhibit limited geographic distributions and high potential risk of global extinction. Despite their importance, they remain, compared to terrestrial vertebrates, highly understudied in their biogeography, ecological/evolutionary significance, and exposure and vulnerability to global change. We propose to pool data and expertise in three research labs at Yale to address this shortcoming. Specifically, we propose to conduct highly interdisciplinary research on the conservation biogeography, phylogeny and function of North American freshwater fishes in the face of global change. Using new web-mapping tools, phylogenetic and functional data, and environmental layers we plan to conduct geographic and species level assessments of the potential loss of species, function and evolutionary history under projected environmental change.