NEW! Working with the Data boxes demonstrate important quantitative concepts with examples, and allows for quick reference when reviewing for exams. More than 150 figures, tables, and graphs are either completely new or updated with new data and a modern, more consistent design. Selected figures have new a design feature that highlights key information, interpretations, or questions. NEW! Chapter 3: Behavioral Ecology and Chapter 25: Ecosystem Dynamics under Changing Climates have been added. Selected topics have been reorganized and condensed in response to feedback from professors and students. Chapter 8: Population Parameters and Demographic Techniques streamlines material from Chapters 9 and 10 of theFifth Edition, and Chapter 5 and Chapter 6 have also been reorganized to summarize concepts from Chapters 4 to 7 of theFifth Edition. Extensive revisions have been made to chapters on conservation biology (Chapter 17), community organization, and primary production (Chapter 22). NEW! Researcher Profiles at the beginning of each part emphasize the historical development of ecology by highlighting the people who helped build the discipline. NEW! JPEGs of all the photos, figures, graphs, and tables from the text will be available for download on the Instructor Resource Center. NEW! Key Terms are highlighted at the beginning of each chapter to help students recognize important terms as they read. Figures of species contained within graphs have been redrawn and updated for this edition. Review Questions and Problems have been revised and 30% are new. NEW! A larger trim size gives the Sixth Edition a more friendly, inviting presentation for students.