Bee pollinators are critically important for agricultural and natural ecosystems. Together, wild and managed bee species contribute to the pollination of 80 crops with an estimated annual value of >$200 billion globally, >$29 billion for US agriculture, and >$9 billion for California. REU students in this project will examine the population genetics and phylogenetic relationships of both native bees and honeybees, with sampling and analyses of sequence data from bee populations in the tropics and across California, to investigate the effect of human-induced changes in population structure. These ongoing studies of bee genomics will improve management practices that increase resistance to disease and enhance climate adaptation, and the engagement of REU students will give them hands-on experience with state-of-the-art genomics and phylogenetics in an emerging model system with critical impacts on food production systems throughout the world.