NATIONAL ACADEMY PRESS
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This volume is based on the National Academy of Sciences' colloquium entitled "Chemical Ecology: The Chemistry of Biotic Interaction." The articles appearing in these pages were contributed by speakers at the colloquium. Any opinions, findings, conclusions, or recommendations expressed in this volume are those of the authors and do not necessarily reflect the views of the National Academy of Sciences.
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences.
Library of Congress Cataloging-in-Publication Data
Chemical ecology : the chemistry of biotic interaction / Thomas Eisner and Jerrold Meinwald, editors.
p. cm.
Includes bibliographical references and index.
ISBN 0-309-05281-5 (alk. paper)
1. Chemical ecology. I. Eisner, Thomas, 1929- II. Meinwald, Jerrold, 1927-
QH541. 15.C44C48 1995 95-18685
574.5—dc20 CIP
Copyright 1995 by the National Academy of Sciences. All rights reserved.
Printed in the United States of America
Table of Contents
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Preface |
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The Chemistry of Defense: Theory and Practice |
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The Chemistry of Poisons in Amphibian Skin |
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The Chemistry of Phyletic Dominance |
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The Chemistry of Social Regulation: Multicomponent Signals in Ant Societies: |
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The Chemistry of Eavesdropping, Alarm, and Deceit |
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Polydnavirus-Facilitated Endoparasite Protection Against Host Immune Defenses |
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The Chemistry of Gamete Attraction: Chemical Structures, Biosynthesis, and (A)biotic Degradation of Algal Pheromones |
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The Chemistry of Sex Attraction |
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The Chemistry of Sexual Selection |
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The Chemistry of Signal Transduction |
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Chemical Signals in the Marine Environment: Dispersal, Detection, and Temporal Signal Analysis |
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Analysis of Chemical Signals by Nervous Systems |
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Chemical Ecology: A View from the Pharmaceutical Industry |
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Preface
Ours is a world of sights and sounds. We live by our eyes and ears and tend generally to be oblivious to the chemical happenings in our surrounds. Such happenings are ubiquitous. All organisms engender chemical signals, and all, in their respective ways, respond to the chemical emissions of others. The result is a vast communicative interplay, fundamental to the fabric of life. Organisms use chemicals to lure their mates, associate with symbionts, deter enemies, and fend off pathogens. Chemical ecology is the discipline that is opening our "eyes" to these interactions. It is a multifaceted discipline, intent on deciphering both the chemical structure and the information content of the mediating molecules. And it is a discipline in which discovery is still very much in order, for the interactions themselves remain in large measure to be uncovered.
Chemical ecology has made major progress in recent decades. This reflects, in part, the extraordinary technical innovation that has taken place in analytical chemistry. Highly improved procedures are now available for separating complex mixtures into their individual components, as well as for quantitating and chemically characterizing designated compounds. There has also been a vast increase in the sensitivity of the techniques. Where gram quantities were once needed for elucidation of chemical structure, milligram or even microgram quantities may now suffice. These refinements in sensitivity are of particular importance, given that organisms often produce their signal molecules in vanishingly small amounts.
Progress in chemical ecology has also been fostered by advances in biology itself. Chemical interactions in nature are often social, in the sense
that they occur between conspecifics. Conceptual advances in behavioral biology, particularly sociobiology, have helped put new slants on inquiries into such social phenomena as mate attraction, sexual selection, parental investment, caste determination, and colony organization, all frequently mediated by chemicals. The questions themselves, answered at one level of organization, often lead to inquiries at another level. Studies of pheromones, for instance, first with insects and then with selected mammals, were doubtless influential in prompting the highly promising current inquiries into pheromonal communication in humans. Other biological disciplines are also proving relevant. Virtually every chemically mediated interspecific interaction, whether between predator and prey, herbivore and plant, or parasite and host, lends itself to interpretation in the broadest evolutionary, ecological, population-biological, and molecular-biological terms.
Molecular biology may, in fact, increasingly shape the questions that are asked in chemical ecology. How do given signal molecules arise in the course of evolution? How are they synthesized, and how is the rate and timing of their production controlled? How are they recognized at the level of the receptor? How do noxious chemical signals, designed to repel or poison, affect their intended targets? How is it that receiver organisms are sometimes able to circumvent, counteract, or even secondarily employ, such offensive chemicals? Molecules that transmit information between organisms are a fundamental part of the regulatory chemicals of nature. The rules that apply to intraorganismal chemical regulation apply in large measure to them as well.
Molecules that have signal value in nature sometimes prove to be of use to humans. One need only cite the example of medicinals to underscore the point. Major recent additions to our therapeutic arsenal include ivermectin, cyclosporin, FK-506, and taxol, compounds that can all be expected to have evolved as signaling agents. Many and varied benefits can be expected to be derived from an ongoing search for natural products. Chemical ecologists should become active participants in this search. They have the expertise, gained through laboratory and field experimentation and observation, to rate species by "chemical promise" and therefore to aid in the important task of selecting species for chemical screening. Chemical ecologists are also in a position to provide some assessment of the hidden value of nature. The search for natural products has essentially only begun. Most species, especially microbial forms and invertebrates, remain to be discovered, let alone to be screened for chemicals. What remains unknown is of immense potential value, and deserving of protection, lest we be forever impoverished by its loss. To help in the preservation effort, chemical ecologists will need to speak out as conservationists.
The essays that follow are synopses of lectures delivered at a colloquium on chemical ecology. Almost 150 participants attended the proceedings. The papers do not provide an overview of the discipline but rather give a glimpse into selected research areas that are contributing to advancement of the field. We are immensely grateful to our invited speakers, both for the quality of their communications and for the personal enthusiasm they brought to the meeting. Discussions were convivial and much enlivened by the youthfulness of most of the audience. Four participants, Ian T. Baldwin, Gunnar Bergström, Arnold Brossi, and Amos B. Smith III deserve special thanks, for presiding over the sessions and for leading the discussions. We are also grateful to Jack Halpern, Vice President of the Academy, for asking us to organize the colloquium, and to Bruce Alberts, President of the Academy, for providing introductory remarks at the meeting. For help in preparation of the colloquium we are indebted to Kenneth R. Fulton and Jean Marterre of the Academy and especially to our Cornell associates, Janis Strope and Johane Gervais.
Financial resources for the colloquium were provided by the Academy and supplemented by contributions from a number of industries (American Cyanamid Company, E. I. DuPont de Nemours & Co., Givaudan-Roure Corporation, Merck & Co., Monsanto, Rohm and Haas Company, Schering-Plough Research Institute, Sterling-Winthrop Inc., Syntex, Takasago International Corporation, Zeneca Inc.), to which we are much indebted.
Thomas Eilser
and Jerrold Meinwald