Conservation Genetics


  • Steven M. Chambers

    1. Division of Ecological Services, U.S. Fish and Wildlife Service, P.O. Box 1306, Albuquerque, NM 87103, U.S.A., email
    2. The findings and conclusions in this article are those of the author and do not necessarily represent the views of the U.S. Fish and Wildlife Service.
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Evolutionary Conservation Genetics . Höglund, J. 2009 . Oxford University Press , Oxford , United Kingdom . 198 (ix + 189) pp. $130.00 (hardcover). ISBN 798-0-19-921421-1 .
Conservation Genetics in the Age of Genomics . Amato, G., R. O. A.Desalle, H.Ryder, and H. C.Rosenbaum , editors. 2009. Columbia University Press, New York, NY. 262 (xiv + 248) pp. $65.00 (hardcover). ISBN 978-0-231-12832-2.
Population Genetics for Animal Conservation. Bertorelle, G., M. W.Bruford, H. C.Hauffe, A.Rizzoli, and C.Vernesi, editors. 2009. Cambridge University Press, Cambridge, United Kingdom. Conservation Biology Series 17. 406 (xi + 395) pp. $55.00 (paperback). ISBN 978-0-521-68537-5.

Voipio's (1950) pioneering exploration of the applications of genetics to the management of wild populations received little general notice. Although it received a favorable review in the Journal of Wildlife Management (Evans 1951), my search of that journal failed to detect any subsequent citations. The value of wild sources of genetic variation for crop improvement had long been accepted, but for the eventual emergence of a broader science of conservation genetics we owe much to the efforts of O. H. Frankel in the 1970s.

The three new books indicate the persistence and growth of conservation genetics. Evolutionary Conservation Genetics by Höglund is a short book on genetic variation in the wild. The other two books are multiauthor volumes resulting from scientific conferences. All cover a broad range of topics in conservation genetics.

Evolutionary Conservation Genetics deals with genetic variation in natural populations and its implications for the survival of species in the wild. Topics are illustrated with the results of field studies, which are mostly of vertebrates, but there are some examples with plants and invertebrates. The book provides introductions to essential topics such as measurement of genetic variation, population structure, inbreeding, effective population size, population bottlenecks, adaptive genetic variation, and genomic applications. An impediment to its use as a textbook is that terms are not always well defined.

The strengths of Evolutionary Conservation Genetics include its presentation of studies that integrate ecological and behavioral factors with genetic data and its forward-looking discussions of the potential contributions of newer approaches, such as landscape genetics, SNPs (single nucleotide polymorphisms), and QTLs (quantitative trait loci), in establishing a field of “ecological genomics.” The book is not a comprehensive treatment of the field of conservation genetics, and the author makes clear in his preface that he will not address issues involving management. Taxonomy and captive propagation are important applications in conservation genetics that are not covered. Units of genetic conservation are discussed only briefly in the final chapter. For its stated purpose, however, it provides a useful overview of conservation genetics and a glimpse of how new approaches may enhance our understanding of evolutionary forces that affect vulnerable species.

Conservation Genetics in the Age of Genomics (hereafter Genomics) is a collection of essays derived from conferences in San Diego (2000) and at the American Museum of Natural History (2001). There are somewhat redundant chapters that describe various methods of genomic analysis, but it is not until Chapter 14 (of 20) that an informative definition of genomics is provided. The title suggested to me the book would explain how genomics affects conservation genetics, but, disappointingly, it did not. The other two books I reviewed provide much more satisfying discussions of what one might expect from new technology and approaches.

The essays in Genomics cover a wide range of topics that are central to conservation genetics. In addition to descriptions of molecular genetic techniques, there are chapters on population genetics, captive populations, marine conservation, collections (including tissues, museums, and zoos), information management, crop transgenes, cloning, and legal issues concerning ownership and control of information. As “essays,” most chapters are more informal and less technical than those in Population Genetics for Animal Conservation. With few exceptions, examples concern vertebrates.

There are areas where more assertive editing would have improved the book. In addition to the redundancy of chapters on genomics, some chapters on collections could have been consolidated. Some entries in the list of contributors are so abbreviated that they are virtually useless. Judging from dates of references cited at the end of each chapter, some papers were only minimally updated subsequent to the conferences, and the length of time between the conferences and the book's publication was long.

Despite these flaws, there is much to take note of in this book, including some must-read chapters. Hedrick points out, in his chapter on applications from “classical” population genetics, that statistically significant differences between genetic samples may not be biologically meaningful. In his review of captive breeding, Lacy is skeptical of the ability of genomic data to replace classical pedigree analysis. Rogers et al. lament that collections are not sufficiently valued and describe their vulnerability to loss from neglect, war, and natural catastrophe. Ellstrand's review of risks associated with genetically modified organisms summarizes studies of genetic interactions between crop plants and their wild relatives, and he provides a clear, logical framework for evaluating risks of adverse consequences. The authors of chapters on cloning do not see a substantial role for it in endangered species conservation.

My favorite of the three books is Population Genetics for Animal Conservation. The subject matter of individual chapters ranges from analytical techniques, to special applications, to case studies. Common to all chapters is a commitment to provide practical analytical tools and approaches and examples of their application. The result is a satisfying integration of theory and results of field studies.

The predictive evaluation of the role of genomics that I found lacking in Genomics is amply provided in Genetics for Animal Conservation. Forecasts of how genomic approaches may change our understanding of questions in conservation genetics are provided in chapters by Vernesi and Bruford and by Beaumont. Beaumont predicts genomics will enhance our understanding of population histories and adaptive differences and our ability to characterize populations through DNA from hairs or other trace material and to establish pedigrees of wild populations.

Early chapters review various methods and software for analyzing and portraying genetic variation, including coalescence analysis, STRUCTURE, nested-clade analysis, and networks. The authors describe uncertainties and possible misapplications that should be considered by users of these methods. Other chapters focus on specific topics, including the value and evaluation of adaptive genetic diversity, detecting success of translocations, noninvasive sampling, and ancient DNA (broadly defined as DNA from any nonliving source).

Case studies are provided in chapters on Galápagos tortoises by Ciofi et al. and marine mammals by Hoelzel that demonstrate the value of integrating information on feeding behavior, social structure, and ecology and the need to use both lineage (such as mitochondrial DNA) and nuclear markers to understand the genetic structure of populations and their taxonomic standing. In a chapter on genetic units, Bruford portrays as undecided the controversy over competing studies led by Ramey and by King on whether the Preble's meadow jumping mouse (Zapus hudsonius preblei) is a valid subspecies. He is apparently unaware of an independent, scientific review of the issue (Sustainable Ecosystems Institute 2006) that supported the finding of the King group that the subspecies is valid and of the political context of the controversy (Hedrick 2010). The polemical reference in the title of this chapter (“time's up for subspecies”) is premature, as demonstrated by the genetic support for subspecies of Galápagos tortoises described in the chapter by Ciofi et al. There remain examples of subspecies designations that are based on trivial characters, but why not recognize those that are supported by genetic data or multiple, concordant characters?

Genetics for Animal Conservation has useful indexes, including one for software. Few examples concern invertebrates, and true to its title, there is little on plants. The editors describe the volume as an advanced textbook that reviews advanced analytical approaches and examples of their successful application. Its use as a textbook for a course in conservation genetics would require supplemental readings to cover plants, landscape genetics, and captive propagation. It would provide advanced undergraduates or beginning graduate students with a broad array of topics and methods with which to evaluate their interest in conservation genetics, and it would help these students develop a research question if they are interested in pursing the subject. Above all, the book conveys a sense of excitement, tempered with humility, about pursuing questions in conservation genetics.

An emerging area that receives little explicit attention in these three books is the challenge presented by climate change to the persistence of species (Hoelzel 2010). The attention of each book to evaluation of adaptive genetic variation, however, provides a basis for exploring the consequences of rapid changes in selective forces.