Detailed Contents

About the Authors xvii

Preface xviii

Chapter 1 Introduction: Ecology, Evolution, and the Scientific Method 1

Searching for Life at the Bottom of the Ocean 1

Ecological systems exist in a hierarchy of organization 3

    Individuals 3

    Populations and Species 3

    Communities 5

    Ecosystems 5

    The Biosphere 6

    Studying Ecology at Different Levels of Organization 6

Ecological systems are governed by physical and biological principles 8

    Conservation of Matter and Energy 8

    Dynamic Steady States 8

    Evolution 9

Different organisms play diverse roles in ecological systems 10

    Broad Evolutionary Patterns 10

    Categorizing Species Based on Sources of Energy 15

    Types of Species Interactions 15

    Habitat versus Niche 17

Scientists use several approaches to studying ecology 20

    Observations, Hypotheses, and Predictions 20

    Testing Hypotheses with Manipulative Experiments 21

    Alternative Approaches to Manipulative Experiments 23

ANALYZING ECOLOGY
Why Do We Calculate Means and Variances? 24

Humans influence ecological systems 26

    The Role of Ecologists 27

ECOLOGY TODAY: CONNECTING THE CONCEPTS
The California Sea Otter 28

PART I LIFE AND THE PHYSICAL ENVIRONMENT

Chapter 2 Adaptations to Aquatic Environments 32

The Evolution of Whales 33

Water has many properties favorable to life 34

    Thermal Properties of Water 34

    Density and Viscosity of Water 35

    Dissolved Inorganic Nutrients 36

Animals and plants face the challenge of water and salt balance 40

    Salt Balance in Aquatic Animals 40

    Adaptations in Freshwater Animals 41

    Adaptations in Saltwater Animals 42

    Salt Balance in Aquatic Plants 43

ANALYZING ECOLOGY
Standard Deviation and Standard Error 44

The uptake of gases from water is limited by diffusion 45

    Carbon Dioxide 45

    Oxygen 47

Temperature limits the occurrence of aquatic life 49

    Heat and Biological Molecules 49

    Cold Temperatures and Freezing 50

    Thermal Optima 51

ECOLOGY TODAY: CONNECTING THE CONCEPTS
The Decline of Coral Reefs 52

GRAPHING THE DATA
Determining Q10 Values in Salmon 55

viii

Chapter 3 Adaptations to Terrestrial Environments 56

The Evolution of Camels 57

Most terrestrial plants obtain nutrients and water from the soil 58

    Soil Nutrients 58

    Soil Structure and Water-Holding Capacity 58

    Osmotic Pressure and Water Uptake 60

    Transpiration and the Cohesion–Tension Theory 62

Sunlight provides the energy for photosynthesis 64

    Available and Absorbed Solar Energy 64

    Photosynthesis 66

    Structural Adaptations to Water Stress 71

Terrestrial environments pose a challenge for animals to balance water, salt, and nitrogen 71

    Water and Salt Balance in Animals 72

ANALYZING ECOLOGY
Different Types of Variables 74

    Water and Nitrogen Balance in Animals 74

Adaptations to different temperatures allow terrestrial life to exist around the planet 75

    Sources of Heat Gain and Loss 75

    Body Size and Thermal Inertia 77

    Thermoregulation 77

    Ectotherms 77

    Endotherms 78

    Adaptations of the Circulatory System 79

ECOLOGY TODAY: CONNECTING THE CONCEPTS
The Challenge of Growing Cotton 80

GRAPHING THE DATA
Relating Mass to Surface Area and Volume 83

Chapter 4 Adaptations to Variable Environments 84

The Fine-Tuned Phenotypes of Frogs 85

Ecological systems and processes vary in time and space 86

    Temporal Variation 87

    Spatial Variation 87

    Correlation of Spatial and Temporal Dimensions 88

Environmental variation favors the evolution of variable phenotypes 89

    Phenotypic Tradeoffs 89

    Environmental Cues 91

    Response Speed and Reversibility 91

Many organisms have evolved adaptations to variation in enemies, competitors, and mates 92

    Enemies 92

    Competition for Scarce Resources 93

    Mates 94

Many organisms have evolved adaptations to variable abiotic conditions 95

    Temperature 95

    Water Availability 97

    Salinity 98

    Oxygen 98

Migration, storage, and dormancy are strategies to survive extreme environmental variation 99

    Migration 99

    Storage 100

    Dormancy 100

ANALYZING ECOLOGY
Correlations 102

    Adaptations to Prevent Freezing 103

Variation in food quality and quantity is the basis of optimal foraging theory 103

    Central Place Foraging 104

    Risk-Sensitive Foraging 105

    Optimal Diet Composition 107

    Diet Mixing 107

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Responding to Novel Environmental Variation 108

GRAPHING THE DATA
The Foraging Behavior of American Robins 111

Chapter 5 Climates and Soils 112

Where Does Your Garden Grow? 113

Earth is warmed by the greenhouse effect 114

    The Greenhouse Effect 114

    Greenhouse Gases 115

ix

There is an unequal heating of Earth by the Sun 116

    The Path and Angle of the Sun 116

    Seasonal Heating of Earth 117

ANALYZING ECOLOGY
    Regressions 118

The unequal heating of Earth drives air currents in the atmosphere 119

    Properties of Air 119

    Formation of Atmospheric Convection Currents 120

    Earth’s Rotation and the Coriolis Effect 122

Ocean currents also affect the distribution of climates 123

    Gyres 124

    Upwelling 125

    The El Niño–Southern Oscillation 125

    Thermohaline Circulation 126

Smaller-scale geographic features can affect regional and local climates 127

    Continental Land Area 127

    Proximity to Coasts 127

    Rain Shadows 128

Climate and the underlying bedrock interact to create a diversity of soils 129

    Soil Formation 129

    Weathering 130

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Global Climate Change 133

GRAPHING THE DATA
Creating a Climate Diagram 135

Chapter 6 Terrestrial and Aquatic Biomes 136

The World of Wine 137

Terrestrial biomes are categorized by their major plant growth forms 138

    Climate Diagrams 140

ANALYZING ECOLOGY
Mean, Median, and Mode 141

There are nine categories of terrestrial biomes 141

    Tundras 142

    Boreal Forests 142

    Temperate Rainforests 143

    Temperate Seasonal Forests 144

    Woodlands/Shrublands 145

    Temperate Grasslands/Cold Deserts 145

    Tropical Rainforests 146

    Tropical Seasonal Forests/Savannas 147

    Subtropical Deserts 148

Aquatic biomes are categorized by their flow, depth, and salinity 148

    Streams and Rivers 148

    Ponds and Lakes 149

    Freshwater Wetlands 152

    Salt Marshes/Estuaries 153

    Mangrove Swamps 153

    Intertidal Zones 154

    Coral Reefs 154

    The Open Ocean 154

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Changing Biome Boundaries 156

GRAPHING THE DATA
Building Bar Graphs 159

PART II ORGANISMS

Chapter 7 Evolution and Adaptation 160

Darwin’s Finches 161

The process of evolution depends on genetic variation 162

    The Structure of DNA 162

    Genes and Alleles 162

    Dominant and Recessive Alleles 163

    Sources of Genetic Variation 164

Evolution can occur through random processes or through selection 165

    Evolution Through Random Processes 166

    Evolution Through Selection 169

ANALYZING ECOLOGY
Strength of Selection, Heritability, and Response to Selection 172

x

Microevolution operates at the population level 173

    Artificial Selection 173

    Natural Selection 174

Macroevolution operates at the species level and higher levels of taxonomic organization 176

    Phylogenetic Trees 177

    Allopatric Speciation 178

    Sympatric Speciation 178

    Key Innovations 180

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Drug-Resistant Tuberculosis 181

GRAPHING THE DATA
Natural Selection on Finch Beaks 183

Chapter 8 Life Histories 184

Live, Breed, and Die 185

Life history traits represent the schedule of an organism’s life 186

    The Slow-to-Fast Life History Continuum 186

    Combinations of Life History Traits in Plants 187

Life history traits are shaped by trade-offs 189

    The Principle of Allocation 189

    Offspring Number versus Offspring Size 189

ANALYZING ECOLOGY
Coefficients of Determination 190

    Offspring Number versus Parental Care 191

    Fecundity and Parental Care versus Parental Survival 192

    Growth versus Age of Sexual Maturity and Life Span 193

Organisms differ in the number of times that they reproduce, but they eventually become senescent 195

    Semelparity and Iteroparity 195

    Senescence 197

Life histories are sensitive to environmental conditions 198

    Stimuli for Change 198

    The Effects of Resources 199

    Effects of Predation 200

    Effects of Global Warming 200

ECOLOGY TODAY: CONNECTING THE CONCEPTSSelecting On Life Histories With Commercial Fishing 203

GRAPHING THE DATA
Lizard Offspring Number versus Offspring Mass 205

Chapter 9 Reproductive Strategies 206

The Sex Life of Honeybees 207

Reproduction can be sexual or asexual 208

    Sexual Reproduction 208

    Asexual Reproduction 208

    Costs of Sexual Reproduction 210

    Benefits of Sexual Reproduction 211

Organisms can evolve as separate sexes or as hermaphrodites 213

    Comparing Strategies 215

    Selfing versus Outcrossing of Hermaphrodites 216

    Mixed Mating Strategies 216

Sex ratios of offspring are typically balanced, but they can be modified by natural selection 216

    Mechanisms of Sex Determination 216

    Offspring Sex Ratio 218

ANALYZING ECOLOGY
Frequency-Dependent Selection 219

Mating systems describe the pattern of mating between males and females 220

    Promiscuity 221

    Polygamy 221

    Monogamy 222

Sexual selection favors traits that facilitate reproduction 223

    Sexual Dimorphism 223

    The Evolution of Female Choice 224

    Runaway Sexual Selection 225

    The Handicap Principle 226

    Sexual Conflict 226

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Male-hating Microbes 227

GRAPHING THE DATA
Frequency-Dependent Selection 229

xi

Chapter 10 Social Behaviors 230

The Life of a Fungus Farmer 231

Living in groups has costs and benefits 232

    Benefits of Living in Groups 233

    Costs of Living in Groups 234

    Territories 235

    Dominance Hierarchies 236

There are many types of social interactions 236

    The Types of Social Interactions 236

    Altruism and Kin Selection 237

ANALYZING ECOLOGY
Calculating Inclusive Fitness 239

Eusocial species take social interactions to the extreme 240

    Eusociality in Ants, Bees, and Wasps 240

    Eusociality in Other Species 242

    The Origins of Eusociality 242

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Hen-Pecked Chickens 243

GRAPHING THE DATA
How Living In Groups Affects Predation Risk 245

PART III POPULATIONS

Chapter 11 Population Distributions 246

Bringing Back the Mountain Boomer 247

The distribution of populations is limited to ecologically suitable habitats 249

    Determining Suitable Habitats 249

    Ecological Niche Modeling 250

    Habitat Suitability and Global Warming 252

Population distributions have five important characteristics 253

    Geographic Range 254

    Abundance 254

    Density 254

    Dispersion 255

    Dispersal 256

The distribution properties of populations can be estimated 256

    Quantifying the Location and Number of Individuals 256

ANALYZING ECOLOGY
Mark-Recapture Surveys 258

Quantifying the Dispersal of Individuals 258

Population abundance and density are related to geographic range and adult body size 259

    Population Abundance and Geographic Range 260

    Population Density and Adult Body Size 260

Dispersal is essential to colonizing new areas 261

    Dispersal Limitation 261

    Habitat Corridors 261

Many populations live in distinct patches of habitat 263

    The Ideal Free Distribution Among Habitats 263

    Conceptual Models of Spatial Structure 265

ECOLOGY TODAY: CONNECTING THE CONCEPTS
The Invasion of the Emerald Ash Borer 267

GRAPHING THE DATA
An Ideal Free Distribution 269

Chapter 12 Population Growth and Regulation 270

The Human Population Explosion 271

Under ideal conditions, populations can grow rapidly 272

    The Exponential Growth Model 272

    The Geometric Growth Model 273

    Comparing the Exponential and Geometric

    Growth Models 274

    Population Doubling Time 275

Populations have growth limits 276

    Density-Independent Factors 276

    Density-Dependent Factors 277

    Positive Density Dependence 278

    The Logistic Growth Model 281

    Predicting Human Population Growth with the Logistic Equation 283

xii

Population growth rate is influenced by the proportions of individuals in different age, size, and life history classes 283

    Age Structure 283

    Survivorship Curves 285

    Life Tables 285

    Collecting Data for Life Tables 288

ANALYZING ECOLOGY
Calculating Life Table Values 289

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Saving The Sea Turtles 291

GRAPHING THE DATA
Survivorship Curves 293

Chapter 13 Population Dynamics over

    Space and Time 294

Monitoring Moose in Michigan 295

Populations fluctuate naturally over time 296

    Age Structure Fluctuations 297

    Overshoots and Die-offs 298

    Cyclic Population Fluctuations 300

Density dependence with time delays can cause populations to be inherently cyclic 300

    The Inherent Cycling Behavior of Populations 300

    Delayed Density Dependence 301

ANALYZING ECOLOGY
Delayed Density Dependence in the Flixweed 303

    Cycles in Laboratory Populations 303

Chance events can cause small populations to go extinct 305

    Extinction in Small Populations 306

    Extinction Due to Variation in

    Population Growth Rates 307

Metapopulations are composed of subpopulations that can experience independent population dynamics across space 308

    The Fragmented Nature of Habitats 308

    The Basic Model of Metapopulation Dynamics 309

    Observing Metapopulation Dynamics in Nature 310

    The Importance of Patch Size and Patch Isolation 310

ECOLOGY TODAY: CONNECTING THE CONCEPTS
The Recovery of the Black-footed Ferret 313

GRAPHING THE DATA
Exploring the Equilibrium of the Basic Metapopulation Model 315

PART IV SPECIES INTERACTIONS

Chapter 14 Predation and Herbivory 316

A Century-long Mystery of the Lynx and the Hare 317

Predators and herbivores can limit the abundance of populations 319

    Predators 319

    Mesopredators 320

    Herbivores 321

Populations of consumers and consumed populations fluctuate in regular cycles 323

    Creating Predator–Prey Cycles in the Laboratory 324

    Mathematical Models of Predator–Prey Cycles 325

    Functional and Numerical Responses 328

Predation and herbivory favor the evolution of defenses 331

    Defenses Against Predators 331

    Defenses Against Herbivores 336

ANALYZING ECOLOGY
Understanding Statistical Significance 337

ECOLOGY TODAY: CONNECTING THE CONCEPTS
The Trouble with Cats and Rabbits 339

GRAPHING THE DATA
The Functional Response of Wolves 341

Chapter 15 Parasitism and Infectious Diseases 342

The Life of Zombies 343

Many different types of parasites affect the abundance of host species 345

    Ectoparasites 346

xiii

    Endoparasites 347

Parasite and host dynamics are determined by the parasite’s ability to infect the host 352

    Mechanisms of Parasite Transmission 353

    Modes of Entering the Host 354

    Jumping Between Species 354

    Reservoir Species 354

    The Host’s Immune System 354

Parasite and host populations commonly fluctuate in regular cycles 354

    Population Fluctuations in Nature 355

    Modeling Parasite and Host Populations 356

Parasites have evolved offensive strategies while hosts have evolved defensive strategies 358

    Parasite Adaptations 358

    Host Adaptations 359

ANALYZING ECOLOGY
Comparing Two Groups with a t-Test 360

    Coevolution 360

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Of Mice and Men…and Lyme Disease 362

GRAPHING THE DATA
Time Series Data 365

Chapter 16 Competition 366

The Complexity of Competition 367

Competition occurs when individuals experience limited resources 368

    The Role of Resources 369

    The Competitive Exclusion Principle 372

The theory of competition is an extension of logistic growth models 374

    Competition for a Single Resource 374

    Competition for Multiple Resources 378

The outcome of competition can be altered by abiotic conditions, disturbances, and interactions with other species 379

    Abiotic Conditions 379

    Disturbances 380

    Predation and Herbivory 380

Competition can occur through exploitation or direct interference, or it may be apparent competition 381

    Interference Competition: Aggressive Interactions 381

    Interference Competition: Allelopathy 382

    Apparent Competition 382

ANALYZING ECOLOGY
Chi-square Tests 385

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Finding the Forest in the Ferns 386

GRAPHING THE DATA
Competition for a Shared Resource 389

Chapter 17 Mutualism 390

Living with Crabs 391

Mutualisms can improve the acquisition of water, nutrients, and places to live 392

    Acquisition of Resources in Plants 394

    Acquisition of Resources in Animals 395

Mutualisms can aid in defense against enemies 397

    Plant Defense 397

    Animal Defense 398

Mutualisms can facilitate pollination and seed dispersal 400

    Pollination 400

    Seed Dispersal 401

Mutualisms can change when conditions change 402

    From Positive to Negative Interactions 402

    Dealing with Cheaters 403

Mutualisms can affect communities 403

    Effects on Species Distributions 404

    Effects on Communities 404

ANALYZING ECOLOGY
Comparing Two Groups That Do Not Have Normal Distributions 406

    Effects on Ecosystem Function 407

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Dealing with the Death of Dispersers 409

GRAPHING THE DATA
Ecosystem Function of Fungi 411

xiv

PART V COMMUNITIES AND ECOSYSTEMS

Chapter 18 Community Structure 412

A Web of Interactions in Social Spiders 413

Communities can have distinct or gradual boundaries 414

    Community Zonation 414

    Categorizing Communities 416

    Ecotones 416

    Communities with Interdependent versus
    Independent Species Distributions 418

The diversity of a community incorporates both the number and relative abundance of species 420

    Patterns of Abundance Among Species 420

    Rank-Abundance Curves 421

ANALYZING ECOLOGY
Calculating Species Diversity 421

Species diversity is affected by resources, habitat diversity, keystone species, and disturbance 421

    Resources 424

    Habitat Diversity 426

    Keystone Species 426

    Disturbances 428

Communities are organized into food webs 430

    Trophic Levels 430

    Direct versus Indirect Effects 431

    Top-down and Bottom-up Effects 434

Communities respond to disturbances with resistance, with resilience, or by switching among alternative stable states 435

    Community Stability 435

    Alternative Stable States 436

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Lethal Effects of Pesticides at Nonlethal Concentrations 438

GRAPHING THE DATA
Log-Normal Distributions and Rank-Abundance Curves 441

Chapter 19 Community Succession 442

Retreating Glaciers in Alaska 443

Succession occurs in a community when species replace each other over time 444

    Observing Succession 445

    Succession in Terrestrial Environments 447

    Succession in Aquatic Environments 450

ANALYZING ECOLOGY
Quantifying Community Similarity 453

    Change in Species Diversity 454

Succession can occur through different mechanisms 454

    Traits of Early- versus Late-Succession Species 455

    Facilitation, Inhibition, and Tolerance 456

    Tests for the Mechanisms of Succession 457

Succession does not always produce a single climax community 459

    Changes in Climax Communities over Time 459

    Changes in Climax Communities over Space 460

    Transient Climaxes 460

    Creating Gaps in a Climax Community 461

    Climax Communities Under Extreme
    Environmental Conditions 462

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Promoting Succession on a Strip Mine 463

GRAPHING THE DATA
Species Richness at Glacier Bay 465

Chapter 20 Movement of Energy in Ecosystems 466

Worming Your Way into an Ecosystem 467

Primary productivity provides energy to the ecosystem 468

    Primary Productivity 468

    Measuring Primary Productivity 470

    Secondary Production 472

Net primary productivity differs among ecosystems 474

    Primary Productivity Around the World 474

    Drivers of Productivity in Terrestrial Ecosystems 474

    Drivers of Productivity in Aquatic Ecosystems 476

xv

The movement of energy depends on the efficiency of energy flow 479

    Trophic Pyramids 479

    The Efficiencies of Energy Transfers 481

ANALYZING ECOLOGY
Quantifying Trophic Efficiencies 484

    Residence Times 484

    Stoichiometry 485

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Feeding an Ocean of Whales 487

GRAPHING THE DATA
NPP Versus the Total Primary Productivity of Ecosystems 489

Chapter 21 Movement of Elements in Ecosystems 490

Living in a Dead Zone 491

The hydrologic cycle moves many elements through ecosystems 493

    The Hydrologic Cycle 493

    Human Impacts on the Hydrologic Cycle 494

The carbon cycle is closely tied to the movement of energy 494

    The Carbon Cycle 494

    Human Impacts on the Carbon Cycle 496

Nitrogen cycles through ecosystems in many different forms 497

    The Nitrogen Cycle 497

    Human Impacts on the Nitrogen Cycle 499

The phosphorus cycle moves between land water 500

    The Phosphorus Cycle 500

    Human Impacts on the Phosphorus Cycle 501

In terrestrial ecosystems, most nutrients regenerate in the soil 501

    The Importance of Weathering 502

    The Breakdown of Organic Matter 504

    Decomposition Rates Among Terrestrial Ecosystems 506

ANALYZING ECOLOGY
Calculating Decomposition Rates of Leaves 507

In aquatic ecosystems, most nutrients regenerate in the sediments 507

    Allochthonous Inputs to Streams and Wetlands 508

    Decomposition and Sedimentation in Rivers, Lakes, and Oceans 509

    Stratification of Lakes and Oceans 509

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Cycling Nutrients in New Hampshire 510

GRAPHING THE DATA
The Decomposition of Organic Matter 513

PART VI GLOBAL ECOLOGY

Chapter 22 Landscape Ecology, Biogeography, and Global Biodiversity 514

The Magnificent Biodiversity of the Cape Floristic Region 515

Landscape ecology examines ecological patterns and processes at large spatial scales 516

    Causes of Habitat Heterogeneity 516

    Relationships Between Habitat Heterogeneity and Species Diversity 518

    Local and Regional Species Diversity 518

The number of species increases with area 519

    Species-area Relationships 519

    Habitat Fragmentation 521

ANALYZING ECOLOGY
Estimating the Number of Species in an Area 522

The equilibrium theory of island biogeography incorporates both area and isolation 526

    The Evidence 526

    The Theory 527

    Applying the Theory to the Design of Nature Reserves 529

On a global scale, biodiversity is highest near the equator and declines toward the poles 530

    Patterns of Diversity 530

    Processes that Underlie Patterns of Diversity 531

The distribution of species around the world is affected by Earth’s history 534

    Continental Drift 534

    Biogeographic Regions 535

    Historic Climate Change 536

xvi

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Taking a Long Walk for Conservation 537

GRAPHING THE DATA
Species Accumulation Curves 539

Chapter 23 Global Conservation of Biodiversity 540

Protecting Hotspots of Biodiversity 541

The value of biodiversity arises from social, economic, and ecological considerations 543

    Instrumental Values 543

    Intrinsic Values 544

Although extinction is a natural process, its current rate is unprecedented 544

    Background Extinction Rates 545

    A Possible Sixth Mass Extinction 545

    Global Declines in Species Diversity 545

    Global Declines in Genetic Diversity 548

Human activities are causing the loss of biodiversity 550

    Habitat Loss 550

    Overharvesting 552

    Introduced Species 554

    Pollution 556

ANALYZING ECOLOGY
Contaminant Half-Lives 557

    Global Climate Change 557

Conservation efforts can slow or reverse declines in biodiversity 559

    Habitat Protection 560

    Reduced Harvesting 561

    Species Reintroductions 562

ECOLOGY TODAY: CONNECTING THE CONCEPTS
Returning Wolves to Yellowstone 563

GRAPHING THE DATA
Stacked Bar Graphs 565

Appendices

Reading Graphs A-1

Statistical Tables A-7

Answers to Analyzing Ecology and Graphing the Data exercises A-11

Suggested Readings A-19

Glossary G-1

Index I-1

xvii