The Conservation Biology cluster prepares students to identify and protect critical habitat, manage rare and endangered species, and design ecological preserves. The Ecosystem Ecology and Management cluster equips students to conduct ecological field research, manage natural resources on public and private lands, and assess environmental impacts of proposed actions. The Environmental Microbiology and Biotechnology cluster emphasizes laboratory research to assess water and air quality, transport and fate of pollutants, and environmental health in general. Eighteen units must be taken from one of these clusters (the student's primary cluster) and an additional thirteen units from the other two clusters. Students selecting the Conservation Biology cluster or the Ecosystem Ecology and Management cluster take a two-course sequence in Geographic Information Systems (GIS).