This course reviews principal concepts and processes that operate in ecological systems. Beginning with simple interactions between water, the atmosphere, and basic life processes (respiration and photosynthesis), the course develops a dynamical view of ecosystems, covering the principles of energy flow and the cycling of matter, population growth and regulation, evolution, natural selection and behavior, trophic interactions, ecological networks, and community change. The course also introduces students to some of the dominant habitats on earth, including rivers, lakes, wetlands, forests, tundra, deserts, and urban systems. We conclude with a brief consideration of global processes and environmental change.