We use genomic, morphological and environmental data to study the evolution of seasonal adaptation in natural systems. Specifically, we study the evolution and molecular basis of seasonal coat color change in hares (genus Lepus) and ptarmigans (genus Lagopus). We conduct whole genome population genetics analysis, transcriptomic analysis, functional genetic analysis, phylogenetic analysis, and other omic analysis to understand what genes control the ability to seasonal change color and how environmental factors like light control this flexibility in phenotype.