The Importance of Species: Perspectives on Expendability and Triage. Kareiva, P., and S. A. Levin. 2003. Princeton University Press, Princeton, NJ. 443 pp. (427 + xvi). $35.00. ISBN 0–691–09005.
Although patterns of species diversity have been described over a wide range of spatial and temporal scales, remarkably little is known about how interaction web dynamics change when species are lost or added. As a result, conservation biologists have largely failed to marshal compelling arguments for why policymakers should care about the biodiversity crisis and resource managers, more often than not, are surprised by the consequences of their actions. These are serious problems with important societal costs. Hence, it is difficult to imagine a more worthy scientific endeavor than that of understanding the importance of species.
The Importance of Species is a well-edited collection of contributions by some of ecology's most prominent figures and rising stars. It is the product of a symposium honoring the career of R. T. Paine, one of the twentieth century's most influential environmental scientists. Paine's work, and the work of his many students, set the standard for study of the complex ways by which species influence their associated communities and ecosystems. The uniformly high quality of the chapters in this collection reflects a broad respect, if not a near reverence, for this man's character and contributions to ecology.
The volume contains 17 chapters organized into three sections, each prefaced by an introduction that offers a road map to the conceptual issues, approaches, common and uncommon themes, and significant conclusions that follow. Like any edited volume, the chapters vary in approach, style, and substance. However, given the immense diversity of species, the eclectic makeup of past arguments on the nature of species interactions and for the importance of biodiversity, and our vast ignorance of how species link together in defining interaction web dynamics, I found this variation both appropriate and refreshing. Some of the contributions are synthetic, whereas others are original treatments of particular systems or issues. Many would easily qualify as stand-alone papers in the peer-reviewed literature.
The book's first section focuses on species-removal experiments. Although limited to a few tractable species and systems, experiments of this kind provide the most rigorous and least equivocal evidence for the importance of species; they also demonstrate wide-ranging changes in communities and ecosystems following additions or removals of single species. The degree to which these findings apply across species and systems is widely debated, however. The chapters by Menge and Harley give a nascent view of context dependency, based largely on their work in the rocky intertidal zone. The chapter by Schoener and Spiller expands this perspective to the question of variation among species by summarizing and synthesizing a lifetime of experimental research on small Caribbean islands. The section's final chapter by Wootton and Downing considers the pros and cons of two common approaches—the focus on select species versus that on biodiversity—that have been used to investigate the importance of species. Although Wootton and Downing clearly favor the select-species approach, their treatment of the question is comprehensive, insightful, and fair.
The final two sections are necessarily more of a menagerie, although that does not diminish the importance or quality of the constituent chapters. The following brief thematic overview is intended to provide potential readers with a flavor of this diversity. The chapters by Naeem and by Doak and Marvier employ modeling approaches to probe the question of the importance of species in two quite different ways, Naeem by using reliability models from engineering to explore the importance of biodiversity and Doak and Marvier by using matrix models and stochastic simulations to evaluate the importance of the character variation of species in space-limited systems. The chapters by Ruesink and by Schindler et al. focus on variation in the importance of species to lake ecosystems, Ruesink by analyzing a global database on introduced fish species and Schindler et al. by analyzing a detailed time series on phytoplankton species from Lake Washington. The chapters by Morris and by Power and Flecker provide intriguing insights into patterns of redundancy in species interactions, Power and Flecker for plant-virus associations and Morris for plant-pollinator mutualisms. Simberloff's overview of the impacts of single-species extinctions on communities and ecosystems, although brief, is thoughtful and thorough. Palumbi's also brief but important chapter stands alone as an exposé on the evolutionary importance of species. Finally, Leigh's essay is a beautifully written and highly philosophical retrospection and humanistic perspective on the importance of species—a fitting tribute to what I have only heard secondhand of his interesting relationship with Paine and his students and their trips to Tatoosh Island.
One needn't look far in today's world to see the recurring manifestations of our ignorance with respect to the importance of species. This book is not a remedy for that ignorance, although it provides useful examples and approaches. The Importance of Species also affords a heightened perspective on and humility toward both the complexity of nature and the enormity of conservation biology's greatest challenge—the preservation of biodiversity. It is required reading for everyone with a serious interest in the conservation and management of natural resources.