How Species Interact This page intentionally left blank How Species Interact Altering the Standard View on Trophic Ecology Roger Arditi and Lev R. Ginzburg 1 Oxford University Press, Inc., publishes works that further Oxford University’s objective of excellence in research, scholarship, and education. Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi New Delhi Shanghai Taipei Toronto With offi ces in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore South Korea Switzerland Th ailand Turkey Ukraine Vietnam Copyright © 2012 by Oxford University Press Artwork by Amy Dunham and Ksenia Golubkov © 2011 Applied Biomathematics Published by Oxford University Press, Inc. 198 Madison Avenue, New York, New York 10016 www.oup.com Oxford is a registered trademark of Oxford University Press All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitt ed, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, w ithout the prior permission of Oxford University Press. Library of Congress Cataloging-in-Publication Data Arditi, Roger. How species interact : altering the standard view on trophic ecology / Roger Arditi and Lev Ginzburg. p. cm. Includes bibliographical references and index. ISBN 978-0-19-991383-1 (hardcover : alk. paper) 1. Predation (Biology)—Mathematical models. 2. Food chains (Ecology)—Mathematical models. I. Ginzburg, Lev R. II. Title. QL758.A73 2012 591.5′3—dc23 2011034905 1 3 5 7 9 8 6 4 2 Printed in the United States of America on acid-free paper Ce qui est simple est toujours faux. Ce qui ne l’est pas est inutilisable. Paul Valéry, in Mauvaises Pensées et Autres (1942) [ What is simple is always wrong. What is not is useless. Paul Valéry, in Bad Th oughts and Others (1942)] We must learn fr om the mathematician to eliminate and to discard; to keep the type in mind and leave the single case, with all its accidents, alone; and to fi nd in this sacrifi ce of what matt ers litt le and conservation of what matt ers much one of the peculiar excellences of the method of mathematics. D’Arcy W. Th ompson, in On Growth and Form (1917) This page intentionally left blank CONTENTS Acknowledgments xi Acronyms and Symbols xiii Introduction 3 1. Alternative Th eories of Trophic Interaction 8 1.1 Monod versus Contois: Resource-Dependent and Ratio-Dependent Bacteria 9 1.2 Th e Standard Predator-Prey Model of Ecology 1 4 1.3 Th e Arditi-Ginzburg Ratio-Dependent Model 1 7 1.4 Donor Control and Ratio Dependence 22 1.5 Predator-Dependent Models 24 1.6 What Happens at Low Density? Th e Gradual Interference Hypothesis 26 1.7 Biomass Conversion 29 2. Direct Measurements of the Functional Response 33 2.1 Insect Predators and Parasitoids, Snails, Fish, and Others: Laboratory Measurements 35 2.1.1 Manipulating the Consumer Density Alone 35 2.1.2 Measuring Interference in the Presence of a Saturating Functional Response 3 7 2.1.3 Th e Arditi-Akçakaya Predator-Dependent Model 4 0 2.1.4 Application to Literature Data 4 1 2.1.5 Does Interference Increase Gradually? 4 5 2.2 Wasps and Chrysomelids: A Field Experiment 45 2.3 Wolves and Moose: Field Observations 48 2.3.1 Wolf Social Structure and Spatial Scales 4 9 2.3.2 Model Fitt ing and Model Selection Methods 5 0 2.3.3 Th e Wolf-Moose Functional Response Is Ratio Dependent 51 2.4 Additional Direct Tests of Ratio Dependence 5 5 2.4.1 Bark Beetles 56 2.4.2 Shrimp 57 2.4.3 Egg Parasitoids 5 7 2.4.4 Benthic Flatworms 5 9 2.5 Identifying the Functional Response in Time Series 60 2.6 Concluding Summary 6 1 3. Indirect Evidence: Food Chain Equilibria 6 2 3 .1 Cascading Responses to Harvesting at the Top of the Food Chain 63 3 .2 Enrichment Response When the Number of Trophic Levels is Fixed 6 6 3 .3 Enrichment Response When the Number of Trophic Levels Increases with Enrichment 7 1 3.4 Why the World is Green 76 3.5 Th e Paradox of Enrichment 7 7 3.6 Donor Control and Stability of Food Webs 80 4. How Gradual Interference and Ratio Dependence Emerge 8 3 4 .1 Experimental Evidence of the Role of Predator Clustering on the Functional Response 8 4 4.1.1 An Aquatic Microcosm Experiment 85 4.1.2 Predator Aggregations Lead to Ratio Dependence 8 6 4.2 Refuges and Donor Control 89 4.2.1 A Simple Exploratory Th eoretical Model 90 4.2.2 From Donor Control to Ratio Dependence 9 2 4.3 Th e Role of Directed Movements in the Formation of Population Spatial Structures 9 3 4.3.1 Self-Organization Due to Accelerated Movement 94 4.3.2 Spatially Structured Predator-Prey Systems 9 6 4.3.3 How Ratio Dependence Emerges From Directed Movement 1 01 4.4 Ratio Dependence and Biological Control 102 4.4.1 Th e Biological Control Paradox 1 02 4.4.2 Trophotaxis and Biological Control 1 03 4.5 Emergence of Gradual Interference: An Individual-Based Approach 1 08 4.5.1 A Qualitative Model Based on Predator Home Ranges 1 08 4.5.2 An Individual-Based Model Based on Trophotaxis 1 11 [ viii ] C ontents 5. Th e Ratio Dependence Controversy 1 15 5.1 Evidence of Ratio Dependence is Oft en Concealed in the Literature 116 5.2 Th e Paradox of Enrichment and the Cascading Enrichment Response: Is Th ere Any Evidence Th at Th ey Exist? 1 17 5.3 Th e Fallacy of Instantism 1 20 5 .4 How the Ratio-Dependent Model Serves the Debate on the Causes of Cyclicity 1 24 5.5 Mechanistic versus Phenomenological Th eories 1 26 5.6 “Th e Truth is Always in the Middle”: How Much Truth is in Th is Statement? 1 27 6. It Must Be Beautiful 1 29 6.1 Scaling Invariance and Symmetries 130 6.2 Kolmogorov’s Insight 1 35 6.3 Akçakaya’s Ratio-Dependent Model for Lynx-Hare Cycling 1 37 6.4 Th e Limit Myth 1 39 Appendixes 143 3.A Food Chain Responses to Increased Primary Production 1 43 3.A.1 Prey-Dependent Four-Level Food Chain 1 43 3.A.2 Ratio-Dependent Th ree-Level Food Chain 145 3.B Cascading Response in the Ratio-Dependent Model 146 6 .A How a Revised Ecology Textbook Could Look 148 References 151 Index 163 Contents [ IX ]
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