Animals all over the world are being pressured to move to new habitats at higher latitudes and higher elevations. While many species are successfully moving towards the poles, relatively few are migrating upslope as fast as they need to. One intuitive but untested explanation for this mismatch could be that high-elevation habitats do not provide enough oxygen to support lowland species’ essential activities (e.g. foraging, mating, evading predators). As a model organism for testing this hypothesis, the project will use dragonflies, whose extreme aerobic requirements during flight should make them especially sensitive to the low oxygen at high elevations. By combining an integrative set of lab experiments with a large-scale field inventory of dragonfly species in the Rocky Mountains, the research will advance our understanding of the barriers that animals face when dispersing into a new environment. This project will further help scientists and land managers make better forecasts for the kinds of traits that animal species will need in order to establish populations at higher elevations. This work will also provide training opportunities for the next generation of scientists and produce a report about the statuses of dragonfly species on public lands in Colorado. The goal of this project is to test if low oxygen prevents species from dispersing to higher elevations. Using dragonflies as a model, the proposed approach will explore this putative physiological barrier across t