An Introduction to Molecular Ecology

Abstract

As a graduate student in a small department it was apparent that there was a great divide between those who worked at the molecular level and those who worked at the whole organism level, as each had different approaches, interests, and especially vocabulary. Ecologists however have begun to cross that divide as we've used the tools developed by molecular biologists to answer fundamental questions in the fields of ecology, evolution, and conservation. The authors of these two books have independently recognized the need for a textbook that can be used to explain these tools to ecologists who may not have used them before. Each book covers similar material in its own way but they differ in their target audience and thus complement each other rather than overlap. (Each book refers to the field by a different name and I will use the term used by Lowe et al., ecological genetics, throughout this review.) The Beebee and Rowe volume has been written to be used as a textbook for undergraduates or graduates new to ecological genetics, whereas the Lowe et al. volume targets upper-level undergraduates, postgraduate students, and researchers. Both books do an excellent job of reaching their intended targets: I could comfortably use the Beebee and Rowe volume as a textbook for students who have completed introductory courses in ecology and genetics whereas the Lowe et al. volume requires the reader to have a greater depth of background knowledge. The increased depth of coverage of the Lowe et al. book also means that it will be more useful as a resource for researchers in the field. There are strong similarities between the two books in content. Both begin by reviewing the history of the field and justifying why the application of molecular techniques to ecology is so useful. Then, each book reviews the types of molecular data that can be used in ecological studies. Finally, each proceeds to present information about specific fields that are covered in ecological genetics. Each book devotes a chapter to assessment of genetic diversity in natural populations, questions about speciation and hybridization between populations, the ways molecular techniques can help determine mating systems, and the ways these techniques have changed how we determine phylogeny and phylogeography. The Beebee and Rowe book also includes chapters on conservation genetics, microbial ecology, and the use of molecular techniques in assessing the effect of genetically modified crops on natural populations. The main difference between the two books is in the depth of the coverage of the topics. The Lowe et al. volume consistently provides greater detail on how the molecular data can be analyzed in each chapter whereas the Beebee and Rowe book provides that material in an Appendix. This is one of my main criticisms of Beebee and Rowe's volume; the authors are continually referring the reader to the Appendices for more information. I was constantly shuffling between pages trying to read the details of the analyses that the authors were presenting in the main text. If I were to use this volume as a course textbook I'd start with Chapter 1, then teach the material in the two appendices before moving onto Chapter 2. While that's not an issue when designing the course syllabus, it does make reading the book more difficult. Beebee and Rowe's volume does have some features that would make it an excellent textbook for an undergraduate course or an introduction to the topic for an interested reader. Chapter 2 provides a refresher course in basic genetics for readers who may not have recently taken one. Each subsequent chapter (310) addresses one set of problems that ecological genetics can be used to address. The material in each chapter is firmly based on published studies, which are reviewed and cited in the text. Indeed, each chapter provides a great entry point into the primary literature and could be used as a starting point for a more in-depth exploration of the topics. Readers are provided with each chapter's sub-headings as a list of bulleted points at the start of the chapter and a summary list of the main points of the chapter at the end (also in the form of a bulleted list). The text covers approximately 3/4 of the page, leaving a wide margin for annotations. Some annotations have been provided by the authors in the form of bulleted points in the margin already. (My personal preference would be for these not to be included but textbook designers seem to like them.) Given that much of the text is in the form of a literature review, it's nice that the authors have provided appropriate data tables and figures from the papers that they are discussing. These are clear, with adequate captions, and additional explanations are provided in the text. A list of both the figures and tables is provided for the reader to make finding a specific one easier. A companion website accessed 2 October 2004) allows a user to download all of the figures in .JPG format for use in the classroom. There is also a feature on that site that will have Oxford University Press (OUP) send you an e-mail to tell you if new material has been added to the companion site. A glossary of terms is included at the back of the book and it appears to be complete. There is an extensive list of references at the back of the book and the most recent reference is from 2002. In several places, the authors include URLs for web sites that can provide more information about a topic; however there are only a few and they appear to be stable sites. In summary, OUP and the authors have made this a useful textbook for an undergraduate audience. The Lowe et al. book has been designed as an upper level or graduate level textbook and a resource for researchers and will fill that niche well. In all cases its coverage is in much greater depth than the Beebee and Rowe volume and as such I found that it would be more useful to me as a reference volume. Each chapter also draws heavily on the published literature and provides citations in the text for further reading. The literature cited appears at the end of each chapter and is extensive. Lowe et al. provide excellent analyses of the finer points of the techniques that they present. This makes the material more suitable for an advanced audience and more complete. Worked examples of how to do the analyses are common and provide nice models for data analysis. Yet, while the material is more complete, the book itself suffers from several design problems that detract from its utility. In several cases, tables are poorly designed with all text left-justified in the columns so that it is difficult for a reader to extract the important information from them. Many of the tables are crowded onto the page and it is difficult to know which information belongs in what row. I found the table that reviews data analysis software packages, Appendix A, especially hard to use. In some cases, the legends for the tables confuse the reader; for example, there is a typo in the legend for table 5.1 that informs the reader that most chloroplast and mitochondria DNA is paternally inherited. The volume depends heavily on boxes to present details but, in general, the use of boxes for supplemental information is confusing. This is especially true for Chapter 2 where the legend for Table 2.3 (which reviews the types and utility of the various markers that are available) refers the reader to Boxes 2.12.6 for further information. Boxes 2.1 and 2.2 occur in the middle of the chapter and do not address that topic. The material that does expand on genetic markers occurs at the end of the chapter (22 pages from the table!) and is not given a box number. Rather it occurs on gray paper and is headed Essential methods information. In some cases, the detailed material in the box preceded the companion text material by several pages, which made me wonder why the authors thought I needed to know that now when the text was on a different topic. While none of these flaws undermine the science presented in the book they do reduce the usefulness of the book as a teaching or research tool. I checked the publisher's website accessed 2 October 2004) to see if there were any other typos reported and none have been. The publisher's website says the authors will maintain a companion website with worked examples, a test question bank, and relevant links but do not provide a link to that site. A search of the senior author's website accessed 2 October 2004) also does not provide a link. As of this writing, then, it appears that this companion site is not available. In spite of these design problems the Lowe et al. volume is a valuable reference tool for anyone interested in this field. I can strongly recommend either book reviewed here and am encouraged that the great divide seems to be getting smaller.