Every revision of a successful text starts with a plan to update areas where advances have occurred. Thus the initial plans for this sixth edition of Biology were to correct any errors detected by its many users, and to incorporate new findings in rapidly advancing areas of research. In publishing terms, this was to have been a "light" revision. However, that is not what happened. Inspired by the suggestions of reviewers, we found ourselves adding chapters, overhauling the way in which key chapters were organized, adding material and then more material-soon we were knee-deep in a significant revision.

Much of the focus of this sixth edition revision was on Evolution, Ecology, and Botany, areas where there was an opportunity for exciting improvement. To revise these chapters we recruited two young energetic biologists to provide fresh perspective. They brought with them new approaches, fresh ideas, and up-to-date knowledge of their areas of expertise. Indeed, it has been so much fun to work with them that in future editions they will join us as full co-authors of the text.

Please refer to the list of changes posted on this Online Learning Center Website to learn chapter-by-chapter what enhancements we have incorporated. Thank you.