This course concerns biological principles as they apply primarily at tissue, organismic, and population levels of organization. Course topics include developmental biology, animal physiology and homeostatic control systems, endocrinology, neurophysiology and the neuronal basis of behavior. Evidence for evolution is reviewed, as are the tenets of Darwin's theory of evolution by natural selection. The nature and importance of variation among organisms and of stochastic processes in evolution are discussed, as are modern theories of speciation and macroevolution. Finally, the course addresses interactions between organisms and their environments as well as the interactions among organisms in natural communities. Each of the topics of the course is explored from a comparative viewpoint to recognize common principles as well as variations among organisms that indicate evolutionary adaptation to different environments and niches.