The objective of this unique textbook is to present a conceptual synthesis of plant, animal, and microbial ecology. Focusing on the application of ecological and evolutionary principles to the individual organism, the author discusses topics such as genetic variation, nutritional mode, size, growth form, the life cycle, and interactions with the environment. He concludes with a summary of the commonalities and differences in the organismal life histories of microorganisms and macroorganisms. His central premise, illustrated by examples from diverse areas of ecology, is that all organisms have been similarly shaped by evolution operating through differential reproductive success, thereby promoting the development of analogous traits.