Nothing in biology makes sense except in the light of evolution--Theodosius Dobzhansky Evolutionary biology is an exciting field with important implications for all other areas of the biological sciences. Research by faculty in the Evolution Group in the University of Pittsburgh Department of Biological Sciences spans a diversity of topics and organisms, ranging from the molecular evolution of bacterial genomes to the physiological ecology of mammals. A major area of faculty research is in microevolutionary processes and mechanisms, including the evolution of plant mating systems, the roles of selection and genetic constraint in the evolution of separate sexes in plants, and the role of gene interactions in the evolutionary process. The study of macroevolutionary patterns is also a major focus of the group, with emphasis placed on the phylogeny and systematics of birds, reptiles, amphibians, and fossil mammals.