This introductory general text helps students grasp the main concepts of ecology while keeping the presentation more applied than theoretical. Evolution is brought to centre stage throughout the book, as it is needed to support understanding of major concepts. The discussion begins with a brief introduction to the nature and history of the discipline of ecology, followed by section I, which includes two chapters on natural history: life on land and life in water. The intent is to establish a common foundation of natural history upon which to base the later discussions of ecological concepts. The book begins with the natural history of the planet, considers portions of the whole in the middle chapters, and ends with another perspective of the entire planet in the concluding chapter.