ECOLOGYThe Experimental Analysis

of Distribution and Abundance

FIFTH EDITION

Charles J.Krebs

The University of British Columbia

Universities- und Landes-bibliothek DarmstadtBibliothek Biologie

Ir»v.-Nr.

An imprint of Addison Wesley Longman, Inc.San Francisco'Boston New York

Capetown Hong Kong London Madrid Mexico CityMontreal Munich Paris Singapore Sydney Tokyo Toronto

C O N T E N T S I N B R I E F

PART 1 What Is Ecology? 1

CHAPTER 1 Introduction to the Science of Ecology 2

CHAPTER 2 Evolution and Ecology 17

PART 2 The Problem of Distribution: Populations 31

CHAPTER 3 Methods for Analyzing Distributions 32

CHAPTER 4 Factors Tha£ Limit Distributions: Dispersal 41

CHAPTER 5 Factors That Limit Distributions: Habitat Selection 57

CHAPTER 6 Factors That Limit Distributions: Interrelations with Other Species 71

CHAPTER 7 Factors That Limit Distributions: Temperature,Moisture, and Other Physical-Chemical Factors 86

CHAPTER 8 The Relationship Between Distribution and Abundance 106

PART 3 The Problem of Abundance: Populations 115

CHAPTER 9 Population Parameters 116

CHAPTER 10 Demographic Techniques: Vital Statistics 133

CHAPTER 11 Population Growth 157

CHAPTER 12 Species Interactions: Competition 179

CHAPTER 13 Species Interactions: Predation 206

CHAPTER 14 Species Interactions: Herbivory and Mutualism 235

CHAPTER 15 Species Interactions: Disease and Parasitism 258

CHAPTER 16 Population Regulation 280

IV

CONTENTS IN BRIEF V

CHAPTER 17 Applied Problems I: Harvesting Populations 305

CHAPTER 18 Applied Problems II: Pest Control 331

CHAPTER 19 Applied Problems III: Conservation Biology 355

PART 4 Distribution and Abundance at the Community Level 385

CHAPTER 20 The Nature of the Community 386

CHAPTER 21 Community Change 403

CHAPTER 22 Community Organization I: Biodiversity 434

CHAPTER 23 Community Organization II:Predation and Competition in Equilibrial Communities 459

CHAPTER 24 Community Organization III: Disturbance and NonequilibriumCommunities 485

CHAPTER 25 Ecosystem Metabolism I: Primary Production 513

CHAPTER 26 Ecosystem Metabolism II: Secondary Production 537

CHAPTER 27 Ecosystem Metabolism III: Nutrient Cycles 560

CHAPTER 28 Ecosystem Health: Human Impacts 583

EPILOGUE 609J

APPENDIX I A Primer on Population Genetics 610

APPENDIX II Estimation of the Size of the Marked Popluationin Capture-Recapture Studies 612

APPENDIX III Instantaneous and Finite Rates 614

APPENDIX W Species Diversity Measures of Heterogeneity 617

GLOSSARY 619

BIBLIOGRAPHY 623

CREDITS 664

SPECIES INDEX 673

SUBJECT INDEX 680

C O N T E N T S

Preface xviii

PART 1 WHAT IS ECOLOGY? 1

CHAPTER 1 INTRODUCTION TO THE SCIENCE OF ECOLOGY 2

Definition of Ecology 2History of Ecology 3

I Basic Problems and Approaches to Ecology 7Levels of Integration 10Methods of Approach to Ecology 11

*' Application of the Scientific Method to Ecology 11Essay 1.1 Science and Values in Ecology 12Box 1.1 Scientific Method: Definitions of Terms 13Essay 1.2 On Ecological Truth 14Key Concepts 15Selected References 15Questions and Problems 15

CHAPTER 2 EVOLUTION AND ECOLOGY 17What Is Evolution? 17Adaptation 18Box 2.1 What Is Fitness? 19

) Clutch Size in Birds 22Coevolution 2 5Essay 2.1 Evolution and "Arms Races" 26Units of Selection 26

Gametic Selection 21Kin Selection 27Group Selection 21

Summary 27Key Concepts 2 8Selected References 28Questions and Problems 28

VI

CONTENTS VII

PART 2i

CHAPTER 3

CHAPTER 4

CHAPTER 5

CHAPTER 6

THE PROBLEM OF DISTRIBUTION:POPULATIONS 31

METHODS FOR ANALYZING DISTRIBUTIONS 32

Transplant Experiments 32Essay 3.1 Liebigs Law of the Minimum 34Physiological Ecology 3 5Adaptation 36Summary 38Key Concepts 39Selected References 39Questions and Problems 39

FACTORS THAT LIMIT DISTRIBUTIONS: DISPERSAL 41

Examples of Dispersal 41Zebra Mussel (Dreissena polymorpbis) 41Gypsy Moth (Lymantria dispar) 42Chestnut Blight (Cryphonectria parasitica) 44California Sea Otter (Enhydra lutris) 45

The Three Modes of Dispersal 46Essay 4.1 Ships, Ballast Water, and Marine Dispersal 41Box 4.1 Definition of Terms for Introduced Nonnative Species 50Colonization and Extinction 50Evolutionary Advantages of Dispersal 5 3Summary 5 5Key Concepts 55Selected References 56Questions and Problems 56

FACTORS THAT LIMIT DISTRIBUTIONS: HABITAT SELECTION 57

Behavioral Mechanisms of Habitat Selection 57Evolution of Habitat Preferences 65

\ A Theory of Habitat Selection 67Summary 69Key Concepts 69Selected References 69Questions and Problems 70

FACTORS THAT LIMIT DISTRIBUTIONS: INTERRELATIONSWITH OTH ER SPECI ES 71

Predation 71Restriction of Prey by Predators 11Restriction of Predators by Prey 15

(continued)

viii CONTENTS

(Chapter 6, continued)

CHAPTER 7

CHAPTER 8

PART 3CHAPTER 9

Disease and Parasitism 77Allelopathy 78Competition 80Essay 6.1 What is Competition? 82Summary 83Key Concepts 83Selected References 84

(V-

Questions and Problems 84

FACTORS THAT LIMIT DISTRIBUTIONS: TEMPERATURE, MOISTURE,AND OTHER PHYSICAL-CHEMICAL FACTORS 86

Climatology 86 ̂Temperature and Moisture as Limiting Factors 88

Interaction Between Temperature and Moisture 91Adaptations to Temperature and Moisture 94

Light as a Limiting Factor 97Climate Change and Species Distributions 102Summary 103Key Concepts 104Selected References 104Questions and Problems 104

THE RELATIONSHIP BETWEEN DISTRIBUTIONAND ABUNDANCE 106

The Spatial Scale of Geographic Ranges 106Variations in Geographic Range Size 108Range Size and Abundance 111Summary 113Key Concepts 114Selected References 114Questions and Problems 114

THE PROBLEM OF ABUNDANCE 115

POPULATION PARAMETERS 116

The Population as a Unit of Study 116Box 9.1 Definitions of Population Parameters 00Unitary and Modular Organisms 117Estimation of Population Parameters 119Box 9.2 Calculation of Expected Population Density from the Regression

Data Given in Table 9.1 120Measurements of Absolute Density 120Indices of Relative Density 125

CONTENTS IX

Essay 9.1 A Historical Essay in Ecology: The Cormack-Jolly-SeberMark-Recapture Model 126

Natality 128' Mortality 128

Immigration and Emigration 129Limitations of the Population Approach 130Composition of Populations 130Summary 131Key Concepts 131Selected References 131Questions and Problems 132

CHAPTER 10 DEMOGRAPHIC TECHNIQUES: VITAL STATISTICS 133

Life Tables 133•Box 10.1 Calculation of Per Capita Rates 135Intrinsic Capacity for Increase in Numbers 138Essay 10.1 Demographic Projections and Predictions 143Box 10.2 Calculation of the Intrinsic Capacity for Increase

from Lotkas Characteristic Equation 145Reproductive Value 145Age Distributions 146Evolution of Demographic Traits 149Summary 154Key Concepts 154Selected References 154Questions and Problems 155

CHAPTER 11 POPULATION GROWTH 157

> Mathematical Theory 157: Growth in Populations with Discrete Generations 151

Growth in Populations with Overlapping Generations 160Box 11.1 What is Little-r and Why Is It So Confusing? 162Laboratory Tests of the Logistics Theory 163Field Data on Population Growth 164

KEssay 11.1 What Is a "Good" Population Growth Model? 166Box 11.2 A Simple Time-Lag Model of Population Growth 168Time-Lag Models of Population Growth 169Stochastic Models of Population Growth 169Population Projection Matrices 173Summary 176Key Concepts 176Selected References1 177Questions and Problems 177

X CONTENTS

CHAPTER 12

CHAPTER 13

CHAPTER 14

SPECI ES I NTER ACTIONS: COMPETITION 179

Classification of Species Interactions 179' Theories on Competition for Resources 180

Mathematical Model ofLotka and Volterra 180Tilman's Model 182Essay 12.1 What Is a Phase Plane, and What Is an Isocline? 184Competition in Experimental Laboratory Populations 185Competition in Natural Populations 190Evolution- of Competitive Ability 199

Theory of r-Selection and K-Selection 199Grimes Theory of Plant Strategies 201

Character Displacement 201Diffuse Competition and Indirect Effects 202Summary 203Key Concepts 204Selected References 204Questions and Problems 205

SPECIES INTERACTIONS: PREDATION 206

Mathematical Models of Predation 207Discrete Generations 201Continuous Generations 209

Laboratory Studies of Predation 212Field Studies of Predation 216Essay 13.1 Laboratory Studies and Field Studies 211Optimal Foraging Theory 225Evolution of Predator-Prey Systems 228

Warning Coloration 229Group Living 231

Summary 232Key Concepts 232Selected References 232Questions and Problems 233

SPECIES INTERACTIONS: HERBIVORY AND MUTUALISM

Defense Mechanisms in Plants 235Tannins in Oak Trees 238Ants and Acacias 239Spines in a Marine Bryozoan 241Spines and Thorns in Terrestrial Plants 242

Herbivores on the Serengeti Plains 242Can Grazing Benefit Plants? 246Essay 14.1 Herbivory, Economics, and Land Use 241Dynamics of Herbivore Populations 248

Interactive Grazing: Ungulate Irruptions 248Noninteractive Grazing: Finch Populations 251

235

CONTENTS XI

CHAPTER 15

CHAPTER 16

Seed Dispersal: An Example of Mutualism 253Complex Species Interactions 254Summary 256Key Concepts 256Selected References 256Questions and Problems 257

SPECIES INTERACTIONS: DISEASE AND PARASITISM 258

Mathematical Models of Host-Disease Interaction 258Compartment Models with Constant Population Size 259

Essay 15. L What Is the Transmission Coefficient (fi),and Horn Can We Measure It? 261

Compartment Models with Variable Population Size 262Box 15.1 How Can Determine Ro? A Mathematical Excursion 263Effects of Disease on Individuals 264

Effects on Reproductions 264Effects on Mortality 265Effects of Disease on Populations 267

Brucellosis in Ungulates 261Rabies in Wildlife 268Myxomatosis in the European Rabbit 212

, Box 15.2 A Simple Rabies Model 213Evolution of Host-Parasite Systems 275Essay 15.2 What is the Red Queen Hypothesis? 216Summary 277Key Concepts 278Selected References 278Questions and Problems 279

POPULATION REGULATION 280

A Simple Model of Population Regulation 281Historical Views of Population Regulation 282Essay 16.1 Definitions in Population Regulation 283A Modern Synthesis of Population Regulation 288Essay 16.2 Why Is Population Regulation So Controversial? 290Two Approaches to Studying Population Dynamics 293

Key Factor Analysis 293Experimental Analysis 296

Plant Population Regulation 297Source and Sink Populations 299Evolutionary Implications of Population Regulation 300Summary 302Key Concepts 302Selected References 303Questions and Problems 303

x i i CONTENTS

CHAPTER 17

CHAPTER 18

CHAPTER 19

APPLIED PROBLEMS I: HARVESTING POPULATIONS 305

Logistic Models 307Dynamic Pool Models 309Laboratory Studies on Harvesting Theory 316TheConcept of Optimum Yield 318Case Study: The Kingtrab Fishery 319Case Study: The Northern Cod Fishery 321Case Study: Antarctic Whaling 324Risk-Aversive Management Strategies 325Essay 11.1 Principles of Effective Resource Management 326Box 11.1 What Are the Harvest Strategies for a Fishery? 321Summary 328Key Concepts 328Selected References 328Questions and Problems 329

APPLIED PROBLEMS II: PEST CONTROL

Examples of Biological Control 333331

Cottony-Cushion Scale (Icerya purchasi) 333Prickly Pear (Opuntia spp.) 334Floating Fern (Salvinia molesta) 336

Theory of Biological Control 337Genetic Controls of Pests 342Immunocontraception 344Integrated Control 346Generalizations About Biological Control 349Risks of Biological Control 351Summary 3 5 2~v-̂Key Concepts 353Selected References 353Questions and Problems 353

355APPLIED PROBLEMS III: CONSERVATION BIOLOGY

Small-Population Paradigm 355Minimum Viable Populations 356

Box 19.1 What Is Effective Population Size? 359Essay 19.1 Diagnosing a Declining Population 360

The Declining-Population Paradigm 360Overkill 361Habitat Destruction and Fragmentation 362

Essay 19.2 Fragmentation of Habitats and Area-Sensitive Species 361Impacts of Introduced Species 371

Chains of Extinctions 313Reserve Design and Reserve Selection 373Box 19.2 Recovery of Petrels After Eradication of Feral Cats on Marion

Island, Indian Ocean 314Box 19.3 An Algorithm for Choosing Reserves for a Taxonomic Group 315

CONTENTS xiii

PART 4

CHAPTER 20

CHAPTER 21

CHAPTER 22

Examples of Conservation Problems 377Furbish's Lousewart 311

( The Northern Spotted Owl 319Summary 381

, Conclusion 3 82Key Concepts 3 82Selected References 3 82Question and Problems 383

DISTRIBUTION AND ABUNDANCEAT THE COMMUNITY LEVEL 385

THE NATURE OF THE COMMUNITY 386

Dynamic Relations Between Populations 3 86Essay 20.1 What Is the Gaia Hypothesis? 388Community Characteristics 392

Community Boundaries? 392Distributional Relations of Species in Communities 395Indicator Species in Communities 398

Box 20.1 Criteria for Indicator Species 399Summary 400Key Concepts 401Selected References 401Questions and Problems 401

COMMUNITY CHANGE 403

Primary Succession on Mount St. Helens 403Concepts of Succession 406A Simple Mathematical Model of Succession 409Case Studies of Succession 412

Glacial Moraine Succession in Southeastern Alaska 413Lake Michigan Sand-Dune Succession 416

Essay 21.1 Why Is Sphagnum Moss So Common? 417Abandoned Farmland in North Carolina 419

The Climax State 423Patch Dynamics 424Summary 431Key Concepts 431Selected References 431Questions and Problems 432

COMMUNITY ORGANIZATION I: BIODIVERSITY 434

Measurement of Biodiversity 434Essay 22.1 Biodiversity: A Brief History 436Some Examples of Diversity Gradients 43 8

(continued)

x i v CONTENTS

(Chapter 22, continued)

CHAPTER 23

CHAPTER 24

Box 22.1 A Simple Model of Latitudinal Gradients in Biodiversity 443Factors That Might Cause Diversity Gradients 443

History Factory 444Spatial Heterogeneity 445Competition 441Predation 448Climate and Climatic Variability 450

<" Productivity 452Disturbance 452

Local and Regional Diversity 454Summary 456Key Concepts 456Selected References 457Questions and Problems 457

COMMUNITY ORGANIZATION II: PREDATION AND COMPETITIONIN EQUILIBRIAL COMMUNITIES 459

Box 23.1 Measuring Community Importance 461Food Chains and Trophic Levels 463Essay 23.1 Use of Stable Isotopes to Analyze Food Chains 466Functional Roles and Guilds 469Keystone Species 471Dominant Species 474Essay 23.2 Fishing Down Food Webs 411Community Stability 477Restoration Ecology 480

- Summary 482Key Concepts 483Selected References 483Questions and Problems 484

COMMUNITY ORGANIZATION III: DISTURBANCEAND NONEQUILIBRIUM COMMUNITIES 485

Patches and Disturbance 485The Role of Disturbance in Communities 486

Coral Reef Communities 486Essay 24.1 Why Are Corals Bleaching? 489

Rocky Intertidal Communities 491Theoretical Nonequilibrium Models 492Conceptual Models of Community Organization 495Essay 24.2 Biomanipulation of Lakes 499The Special Case of Island Species 501Box 24.1 Measuring Immigration and Extinction Rates 501Multiple Stable States in Communities 508Summary 509Key Concepts 510Selected References 510Questions and Problems 511

CONTENTS XV

CHAPTER 25 ECOSYSTEM METABOLISM I: PRIMARY PRODUCTION 513

Primary Production 515Factors That Limit Primary Productivity 517

Aquatic Communities 518L Marine Communities 518

Freshwater Communities 523Essay 25.1 Nutrient Ratios and Phytoplankton 526

Terrestrial Communities 521Box 25.1 Estimating Primary Production from Satellite Data 528Essay 25.2 Why Does Primary Production Decline with Age in Trees? 532Plant Diversity and Productivity 533Summary 534Key Concepts 534Selected References 535Questions and Problems 535

CHAPTER 26

CHAPTER 27

CHAPTER 28

ECOSYSTEM METABOLISM II: SECONDARY PRODUCTION 537

Measure of Secondary Production 537Box 26.1 Estimating Energy Expenditure with Doubly Labeled Water 540Essay 26.1 Thermodynamics and Ecology 543Problems in Estimating Secondary Production 544Ecological Efficiencies 544What Limits Secondary Production? 549

Grassland Ecosystems 549Essay 26.2 Why Is the World Green? 551

Game Ranching in Africa 554Sustainable Energy Budgets 556Summary 557Key Concepts 557Selected References 558Questions and Problems 558

ECOSYSTEM METABOLISM III: NUTRIENT CYCLES 560

Nutrient Pools and Exchanges ' 560Nutrient Cycles in Forests 562Box 27.1 Estimating Turnover Time for Nutrients 564Efficiency of Nutrient Use 568Acid Rain: The Sulfur Cycle 572Essay 21.1 Acid Rain and the Sudbury Experience 515The Nitrogen Cycle 576Summary 580Key Concepts 581Selected References 581Questions and Problems 582

ECOSYSTEM HEALTH: HUMAN IMPACTS 583

Human Population Growth 583Current Patterns of Population Growth 584

(continued)

xv i CONTENTS

(Chapter 28, continued)

Box 28.1 How Large Is a Billion Anyway? 585Carrying Capacity of the Earth 586

Essay 28.1 The Demographic Transition: An Evolutionary DilemmaBox 28.2 How to Calculate an Ecological Footprint 589The Carbon Cycle 590Individual Plant Responses to CO2 593

Plant Community Responses to CO2 594Climate Change 596Essay 28.2 El Nino and the Southern Oscillation 598Changes in Land Use 600Biotic Invasions and Species Ranges 601Ecosystem Services 603Box 28.3 How Is Biodiversity Related to Ecosystem Function? 604Essay 28.3 On Corals and Climate Change 605Essay 28.4 Economics of Ecosystem Services 606Summary 606Key Concepts 607Selected References 607Questions and Problems 608

587

EPILOGUE

APPENDIX I

APPENDIX II

APPENDIX III

APPENDIX W

GLOSSARY

BIBLIOGRAPHY

CREDITS

SPECIES INDEX

SUBJECT INDEX

609

A Primer on Population Genetics 610

Estimation of the Size of the Marked Popluationin Capture-Recapture Studies 612

Instantaneous and Finite Rates 614

Species Diversity Measures of Heterogeneity 617

619

623

664

613

680