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Wednesday, April 16, 2008

Exploring The Essentials Of Ecology. - Review - book review

Ecology, August, 2000 by Gregg Haertvigsen

Townsend, Colin R., John L. Harper, and Michael Begon. 2000. Essentials of ecology. Blackwell Science, Maiden, Massachusetts. xvii + 552 p. $65.95, ISBN: 0-632-04348-2.

I bet you first looked at the author list on this text and thought the order was backwards. Then you looked at the number of pages and thought "Ah ha! Only 552 pages. This must be a watered-down version of 'the big book.' " Essentials of ecology, however, is a new, refreshing, and portable contribution to the slew of introductory ecology textbooks. I have not adopted the encyclopedic Begon et al.'s Ecology (Begon, Michael, John L. Harper, and Colin R. Townsend. 1996. Blackwell Science, Maiden, Massachusetts), hereafter referred to as the Big Book, for a variety of reasons, including my aversion to books deemed daunting to most students. The stated audience for Essentials is students enrolled in a semester-long, introductory course in ecology. The book is of medium length, is easy to read, and is quite manageable for a single-semester course. Overall, I like the book very much and it currently resides at the top of my list of books for adoption.

The first objective of the book, stated in the first paragraph of the preface, is to help citizens become ecologically literate. This, I believe, is an important goal and happens to be one of my own course's learning objectives. Due to the fact that citizens who study introductory ecology are only a small sector of society, the book will have difficulty achieving this very broad goal. Those who read the book, however, will undoubtedly become more ecologically literate.

This is a valuable book for three reasons: content, approach, and layout. First, the content is strong. Ecological concepts are clearly presented while examples are diverse and important. There is a mix of classic and contemporary research, weighted toward the former. Second, the book approaches ecology as a science and introduces two important aspects of ecology (statistics and evolution) that are rarely so explicitly handled in ecology texts. The first chapter ("Ecology and how to do it") introduces the reader to such topics as classic long-term experiments and the quantitative assessment of data, including discussion of data sampling, accuracy and precision, null hypotheses, modeling techniques, and how to interpret probabilities, particularly the P-value. Interpreting P-values is vitally important to understanding ecology but I question what students will gain from this text. The authors state that a P-value of 0.04 is "powerful enough that the conclusion [of an effect or relationship] can be considered safe." On the next page, however, the authors warn that "very little difference in the data is required to move a P-value from 0.04 to 0.06." Clearly, the interpretation of P-values in terms of safety is problematic but good discussion material for students. Unfortunately, students will rarely find P-values used to support results presented in the text. Despite this problem, the attempt to introduce statistical inference in the introductory chapter should be applauded.

The second chapter discusses evolution and the primary mechanism natural selection. Additional information would have been appreciated, although lengthening the book (for instance, in my lecturing, I discuss the Hardy-Weinberg Law as a powerful null hypothesis for evolution). The chapter is quite adequate for most introductory courses. The text I am currently using and will be dropping has neither explicit discussions of how to do the science of ecology or even the mention of evolution in the index.

Third, the layout and imagery are clear and appealing. Graphics are of high quality and include an abundance of four-tone photographs, although occasionally they provide little information (e.g., an unnumbered photographic figure of annual plants blooming in a desert suffers considerably from enlargement). Graphs are abundant and display data points for regressed relationships and error bars for categorical data. However, they lack statistical values (e.g., I- and [r.sup.2] values) and P-values. Disease dynamics and predator-prey oscillations are important choices for an introductory text but the reader can assess the authors' conclusions only by qualitatively inspecting the graphs. These oversights are inconsistent with the introductory chapter that defines quantitative assessments of data as being essential to understanding ecology as a science.

Side-bar boxes are presented to discuss concepts in more depth. Also, boxed "Topical ECOncerns" discuss important and current processes and problems. These are often related in a personal, testimonial type of discussion with interviews. The use of boxes is extensive in certain sections and may lead some readers to find that these disrupt the flow of the text and encapsulate material that would better be included within the main body of the text, such as the very nice description of the Lotka-Volterra model of competition. Conceptual graphs are displayed using appealing colors, symbols and, at times, goofy cartoons. (For example, a cartoon on predator-prey oscillations displays predators crying over dead offspring with a burgeoning, smiling rodent population looking on. I actually am not sure why the offspring have died when the prey population is abundant, but that will be for the students to consider.) These cartoons should work well for students.

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