How Species Interact: Altering the Standard View on Trophic Ecology

CONTENT S
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 14
1.3 Th e Arditi-Ginzburg Ratio-Dependent Model 17
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 37
2.1.3 Th e Arditi-Akçakaya Predator-Dependent Model 40
2.1.4 Application to Literature Data 41
2.1.5 Does Interference Increase Gradually? 45
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 49
2.3.2 Model Fitt ing and Model Selection Methods 50
2.3.3 Th e Wolf-Moose Functional Response Is
Ratio Dependent 51
2.4 Additional Direct Tests of Ratio Dependence 55
2.4.1 Bark Beetles 56
2.4.2 Shrimp 57
2.4.3 Egg Parasitoids 57
2.4.4 Benthic Flatworms 59
2.5 Identifying the Functional Response in Time Series 60
2.6 Concluding Summary 61
3. Indirect Evidence: Food Chain Equilibria 62
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 66
3.3 Enrichment Response When the Number of Trophic Levels
Increases with Enrichment 71
3.4 Why the World is Green 76
3.5 Th e Paradox of Enrichment 77
3.6 Donor Control and Stability of Food Webs 80
4. How Gradual Interference and Ratio Dependence Emerge 83
4.1 Experimental Evidence of the Role of Predator Clustering on the
Functional Response 84
4.1.1 An Aquatic Microcosm Experiment 85
4.1.2 Predator Aggregations Lead to Ratio Dependence 86
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 92
4.3 Th e Role of Directed Movements in the Formation of Population
Spatial Structures 93
4.3.1 Self-Organization Due to Accelerated Movement 94
4.3.2 Spatially Structured Predator-Prey Systems 96
4.3.3 How Ratio Dependence Emerges From
Directed Movement 101
4.4 Ratio Dependence and Biological Control 102
4.4.1 Th e Biological Control Paradox 102
4.4.2 Trophotaxis and Biological Control 103
4.5 Emergence of Gradual Interference: An
Individual-Based Approach 108
4.5.1 A Qualitative Model Based on Predator
Home Ranges 108
4.5.2 An Individual-Based Model Based on
Trophotaxis 111
5. Th e Ratio Dependence Controversy 115
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? 117
5.3 Th e Fallacy of Instantism 120
5.4 How the Ratio-Dependent Model Serves the Debate on the
Causes of Cyclicity 124
5.5 Mechanistic versus Phenomenological Th eories 126
5.6 “Th e Truth is Always in the Middle”: How Much Truth is in Th is
Statement? 127
6. It Must Be Beautiful 129
6.1 Scaling Invariance and Symmetries 130
6.2 Kolmogorov’s Insight 135
6.3 Akçakaya’s Ratio-Dependent Model for Lynx-Hare
Cycling 137
6.4 Th e Limit Myth 139
Appendixes 143
3.A Food Chain Responses to Increased Primary
Production 143
3.A.1 Prey-Dependent Four-Level Food Chain 143
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