Food Webs (mpb-50) (ebook)

Argumento de Food Webs (mpb-50) (ebook)

Human impacts are dramatically altering our natural ecosystems but the exact repercussions on ecological sustainability and function remain unclear. As a result, food web theory has experienced a proliferation of research seeking to address these critical areas. Arguing that the various recent and classical food web theories can be looked at collectively and in a highly consistent and testable way, Food Webs synthesizes and reconciles modern and classical perspectives into a general unified theory.

Kevin McCann brings together outcomes from population-, community-, and ecosystem-level approaches under the common currency of energy or material fluxes. He shows that these approaches--often studied in isolation--all have the same general implications in terms of population dynamic stability. Specifically, increased fluxes of energy or material tend to destabilize populations, communities, and whole ecosystems. With this understanding, stabilizing structures at different levels of the ecological hierarchy can be identified and any population-, community-, or ecosystem-level structures that mute energy or material flow also stabilize systems dynamics. McCann uses this powerful general framework to discuss the effects of human impact on the stability and sustainability of ecological systems, and he demonstrates that there is clear empirical evidence that the structures supporting ecological systems have been dangerously eroded.

Uniting the latest research on food webs with classical theories, this book will be a standard source in the understanding of natural food web functions.

"Food Webs is an imaginative but very concise book in terms of methodology and selection of concepts. It is extremely coherent, though some may think extremely selective in the models and concepts used. But to build a food web theory across different scales of organization, from single populations to real multispecies interaction networks, this selectivity is needed, and the unifying concept of stability makes it fascinating."--Jose M. Montoya, Ecology

"McCann builds an elegant and concise framework to understand the emergent dynamics of food web systems. Precise and straightforward mathematics, clear definitions and models, and excellent descriptions make this an essential book for any community ecologist."--Marcel Holyoak, University of California, Davis

"Understanding the structure of food webs is one of the major challenges for science in the twenty-first century. McCann provides a well-organized introduction into what has been done over the last thirty years and he offers deep insights and novel approaches that will pave the way for all future studies. This may well be one of the most important and influential books in ecology for several decades."--Andrew Dobson, Princeton University

"Synthesizing a range of theoretical and empirical literature, this stimulating and timely book brings out specific structural features of food webs that can broadly stabilize ecological dynamics. The perspective provided by McCann as he builds from single species models, to modules of a few interacting species, to entire food webs, is crucial for understanding the dynamics of natural systems."--Robert D. Holt, University of Florida

"Representing a major advance in ecological theory, this book is an up-to-date synthesis of what is known about the dynamics of food webs. Brilliant and original, it goes beyond anything else currently in print and will provide a foundation in this subject area for years to come."--Donald L. DeAngelis, University of Miami

"There is no equivalent book that reviews food web theory, emphasizing both dynamic aspects and biological constraints. This book will appeal to ecologists across a range of subfields, applied mathematicians, and certain physicists. Providing information and approaches not found elsewhere, it will have an impact on the field."--Alan Hastings, University of California, Davis

"This is potentially an indispensable book for ecologists and paleoecologists alike, synthesizing food-web theory and outcomes from population-level up to whole-ecosystem-level approaches. McCann offers clear explanations of the dynamics of food webs using a mathematical approach, and while the book will be of particular use to graduate students, it may also be of substantial use to undergraduate students as an advanced but very thorough introduction to the subject."--Jo Hellawell, Priscum

"This is a must-read for ecologists interested in ecosystem dynamics."--Choice0Preface xi
Part 1: THE PROBLEM AND THE APPROACH

Chapter 1. The Balance of Nature: What Is It and Why Care? 3
1.1 Balancing a Noisy System 3
1.2 Ecosystem Stability and Sustainability 6
1.3 Of Food Webs, Stability, and Function 9
1.4 Ecological Instability and Collapse 10
1.5 A Theory for Food Webs 17

Chapter 2. A Primer for Dynamical Systems 20
2.1 Qualitative Approaches to Complex Problems 20
2.2 Dynamical Systems 22
2.3 Case Study: Hopf Bifurcation in an Aquatic Microcosm 42
2.4 Summary of Key Points 45

Chapter 3. Of Modules, Motifs, and Whole Webs 47
Part 2: FOOD WEB MODULES: FROM POPULATIONS TO SMALL FOOD WEBS

Chapter 4. Excitable and Nonexcitable Population Dynamics 53
4.1 Continuous Resource Dynamics 53
4.2 From Nonexcitable to Excitable Population Dynamics 56
4.3 Stage-Structured Resource Dynamics 61
4.4 Empirical Evidence for Excitable Dynamics 63
4.5 Summary: The Dual Nature of Population Growth Rates 65

Chapter 5. Consumer-Resource Dynamics: Building Consumptive Food Webs 67
5.1 Interaction Strength 67
5.2 Consumer-Resource Interactions: Two Qualitative Responses to Changes in a Parameter 71
5.3 Summary 79
5.4 Further Assumptions about the C-R Model 80
5.5 Some Nonequilibrium Thoughts 83
5.6 C-R Dynamics in Nature 84
5.7 Summary 88

Chapter 6. Lagged Consumer-Resource Dynamics 89
6.1 Discrete Consumer-Resource Interactions 90
6.2 Stage-Structured Consumer-Resource Dynamics 94
6.3 Stage-Structured Interactions and Alternative States 97
6.4 Empirical Results 100
6.5 Summary 101

Chapter 7. Food Chains and Omnivory 103
7.1 A Familiar Modular Example: Food Chains 105
7.2 Omnivory 110
7.3 Stage Structure and Food Chain Stability 116
7.4 Empirical Results 118
7.5 Summary 121

Chapter 8. More Modules 123
8.1 Generalists and Food Web Dynamics 123
8.2 The Diamond and the Intraguild Predator 132
8.3 Empirical Results 137
8.4 Summary 140
Part 3: TOWARD WHOLE SYSTEMS

Chapter 9. Coupling Modules in Space: A Landscape Theory 145
9.1 Variability, Space, and Food Webs 145
9.2 Individual Traits and a Landscape-Scale Module 147
9.3 Mobile Adaptive Consumers 151
9.4 Food Webs in Space 155
9.5 Asymmetric Flux Rates through Food Webs 160
9.6 Dynamical Implications on the Landscape 162
9.7 Empirical Evidence 164
9.8 Summary 169

Chapter 10. Classic Food Web Theory 170
10.1 The Classic Approach 170
10.2 Matrices and Local Stability 172
10.3 Gershgorin Discs for Community Matrices: An Intuitive Approach to Eigenvalues 172
10.4 A Controlled Approach to Food Web Matrices 175
10.5 Some Classic Whole-Matrix Results 178
10.6 Recent Whole Community Approaches 184
10.7 Summary 188

Chapter 11. Adding the Ecosystem 189
11.1 Grazing Food Webs and Whole Ecosystems 189
11.2 The N-R-D Module 192
11.3 Detritus and C-R Interactions 194
11.4 Nonequilibrium Dynamics and Detritus as a Distributor 197
11.5 Discussion 199
11.6 Summary 199

Chapter 12. Food Webs as Complex Adaptive Systems 201
12.1 Searching for Empirical Signatures 201
12.2 Adaptive Behavior, Changing Food Web Topology, and Ecosystem Size 202
12.3 Empirical Results for Canadian Shield Lake Ecosystems 206
12.4 Subsidies, Opportunists, and Homogenization 213
12.5 Humans in the Food Web 215
Bibliography 219
Index 235