Hybrid camouflage variation: Snowshoe hares molt from a brown coat to a white coat in winter. In some populations, however, where winter snow is less extensive, hares molt from a brown coat to a brown coat. Jones et al. show that regulation of the pigmentation gene Agouti is responsible for the winter coat color change. Hybridization with jackrabbits has led to introgression around this gene that facilitates the brown winter morph. Hybridization appears to have provided important adaptive variation to the snowshoe hare. Science , this issue p. 1355