Dr. Joel Cracraft's research on the systematics and evolution of birds, speciation analysis, and biogeography are all components of his interests in understanding how biotas originate and change over time, and how one understands patterns and processes of diversification. A major effort in his laboratory involves a detailed description of one of the most spectacular examples of "adaptive radiation": the birds of paradise of New Guinea and surrounding areas. A second major project involving his research group is contributing to building the avian Tree of Life, with a focus on the phylogenetic history of the songbirds, which comprise about 60% of all living birds.