Elements of Ecology (8th Edition)

Book Preface

The first edition of Elements of Ecology appeared in 1976 as a short version of Ecology and Field Biology. Since that time, Elements of Ecology has evolved into a textbook intended for use in a one-semester introduction to ecology course. Although the primary readership will be students majoring in the life sciences, in writing this text we were guided by our belief that ecology should be part of a liberal education. We believe that students who major in such diverse fields as economics, sociology, engineering, political science, law, history, English, languages, and the like should have some basic understanding of ecology for the simple reason that it impinges on their lives.

New for the Eighth Edition
For those familiar with this text, you will notice a number of changes in this new edition of Elements of Ecology. In addition to updating many of the examples and topics to reflect the most recent research and results in the fi eld of ecology, we have made a number of changes in the organization and content of the text. An important objective of the text is to use the concept of adaptation through natural selection as a framework for unifying the study of ecology, linking pattern and process across the hierarchical levels of ecological study: individual organisms, populations, communities, and ecosystems. Many of the changes made in previous editions have focused on this objective, and the changes to this edition continue to work toward this goal.

Life History Patterns Chapter Returned to Part Three
Despite all previous efforts, we feel that we did not fully meet this objective in the discussion of populations (Part Three) in the seventh edition. In hindsight, we believe that this shortcoming was a result of our decision to move the presentation of Life History from Part Three (Populations) to Part Two (The Organisms and Its Environment) in the sixth edition. By moving Life History to Part Two we were trying to maintain the theme of trade-offs and constraints in the evolution of characteristics that is developed in Chapter 6 (Plant Adaptations to the Environment) and Chapter 7 (Animal Adaptations to the Environment). However, it is the discussion of life histories, specifically the discussion of adaptations relating to age-specific patterns of survival and fecundity (reproduction), that provide a direct link between natural selection and population dynamics. For this reason, we have returned the chapter on Life History to Part Three (Populations). The chapter now follows Chapter 10 (Population Growth). In addition, we have revised the materials that are presented to make explicit the links between life history characteristics and population dynamics using the framework of life tables that is developed in Chapter 10 (Population Growth).

Restructured Part Four: Species Interactions
Another major change that we have introduced in the eighth edition to emphasize the concept of adaptation through natural selection as a framework for unifying the study of ecology is in the restructured presentation of Part Four, Species Interactions. In previous editions, Part Four consisted of three chapters that introduced the four major species interactions of competition, predation, parasitism, and mutualism (and the broader topic of facilitation). This format, however, did not provide a general framework for viewing the role of population interactions in the process of evolution by natural selection that is common to all species interactions—the process of coevolution.

New Species Interactions Introductory Chapter
To meet this need, we now open Part Four (Species Interactions) with a new chapter entitled Species Interactions, Population Dynamics, and Natural Selection. The objective of this new chapter is to introduce the variety of species interactions that occur among populations, and to explore how these interactions infl uence the respective populations (species) involved at two timescales: (1) the infl uence of species interactions on the processes of mortality and reproduction, which directly influence population dynamics, and (2) the role of species interactio as agents of natural selection by infl uencing the relative fitness of individuals within the population(s). The chapter provides a common framework for exploring the specific species interactions that are introduced in the chapters of Part Four that follow.