1 Organisms and Their Environment

Texto completo

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CHAPTER

1

The Web of Life

2

Deformity and Decline in Amphibian Populations: A Case Study 2

Introduction 3

CONCEPT 1.1 Eventsin the natural world are interconnected. 3

Connections in Nature 3

CONCEPT 1.2 Ecology is the scientific study of interactions between organisms and their environment. 8

Ecology 8

UNIT

1

Organisms and Their Environment

CHAPTER

2

The Physical Environment

22

Climatic Variation and Salmon Abundance: A Case Study 22

Introduction 23

CONCEPT 2.1 Climate is the most fundamental component of the physicalenvironment. 23

Climate 23

CONCEPT 2.2 Winds and ocean currents result from differences in solar radiation across Earth'ssurface. 26 Atmospheric and Oceanic Circulation 26

CONCEPT 2.3 large-scale atmospheric and oceanic circulation patterns establish global patterns of temperature and precipitation. 31

Global Climatic Pattems 31

CONCEPT 1.3 Ecologists evaluate competing hypotheses about natural systems with observations, experiments, and models. 13

Answering Ecological Questions 13 ECOLOGICALTOOLKIT1.1 Designing Ecological

Experiments 16

A CASESTUDYREVISITEDDeformity and Declinein Amphibian Populations 17

CONNECTIONSIN NATURE Mission Impossible? 18

CONCEPT 2.4 Regionalclimates reflect the influenceof the distributionofoceans and continents, mountains, and

vegetation. 34

Regional Climatic Influences 34

CONCEPT 2.5 Seasonal and long-term climatic variation are associated with changes in Earth's position relative to the sun. 37

Climatic Variation over Time 37

CONCEPT 2.6 Salinity, acidity, and oxygen concentrations

are major determinants of the chemical

environment. 42

The Chemical Environment 42

A CASESTUDYREVISITEDClimatic Variation and Salmon Abundance 45

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Contents

CHAPTER

3

The Biosphere

49

The American Serengeti- Twelve Centuries of Change in the Great Plains: A Case Study 49

Introduction 50

CONCEPT 3.1 Terrestrial biomes are characterized by the growth forms of the dominant vegetation. 50 Terrestrial Biomes 50

CONCEPT 3.2 Biologicalzones in freshwater ecosystems are associated with the velocity,depth, temperature, clarity,and chemistry of the water. 68

Freshwater Biological Zones 68

CONCEPT 3.3 Marine biological zones are determined by ocean depth, light availability,and the stabilityof the bottom substrate. 70

Marine Biological Zones 70

A CASESTUDYREVISITEDThe American Serengeti- Twelve Centuries of Change in the Great Plains 76

CONNECTIONSINNATURELong-TermEcological Research 77

CHAPTER

4

Coping with Environmental

Variation: Temperature and

Water

81

Frozen Frogs: A Case Study 81 Introduction 82

CONCEPT

4.1

Eachspecies has a range of environmental tolerances that determines its potential geographic distribution. 82

Response to Environmental Variation 82

CONCEPT 4.2 The temperature of an organism is

determined by exchanges of energy with the external environment. 85

Variation in Temperature 85

CONCEPT 4.3 The water balance of an organism is

determined by exchanges of water and solutes with the external environment. 94

Variation in Water Availability 94 A CASESTUDYREVISITEDFrozenFrogs 101

CONNECTIONSINNATUREDesiccationTolerance, Body Size, and Rarity 102

CHAPTER

5

Coping with Environmental

Variation: Energy

106

T oolmaking Crows: A Case Study 106 Introduction 107

CONCEPT 5.1 Organismsobtain energy from sunlight, from inorganic chemicalcompounds, or through the consumption of organic compounds. 107 Sources of Energy 107

CONCEPT 5.2 Radiant and chemicalenergy captured by autotrophs is converted into stored energy in carbon-carbon bonds. 109

Autotrophy 109

CONCEPT 5.3 Environmentalconstraints have resulted in the evolution of biochemical pathways that improve the efficiencyof photosynthesis. 113

Photosynthetic Pathways 113

CONCEPT 5.4 Heterotrophs have adaptations for acquiring and assimilatingenergy efficientlyfrom a variety of organic sources. 119

Heterotrophy 119

ECOlOGICAlTOOlKIT5.1 Stable Isotopes 120 A CASESTUDYREVISITEDToolmaking Crows 128

CONNECTIONSINNATURETool Use:Adaptation or Learned Behavior? 129

CHAPTER

6

Evolution and Ecology

132

Trophy Hunting and Inadvertent Evolution: A Case

Study 132 Introduction 133

CONCEPT 6.1 Evolutioncan be viewed as genetic change over time or as a process of descent with modification. 133

What Is Evolution? 133

CONCEPT 6.2 Natural selection, genetic drift, and gene flow can cause allele frequencies in a population to change over time. 136

Mechanisms of Evolution 136

CONCEPT 6.3 Natural selection is the only evolutionary mechanism that consistentlycauses adaptive evolution. 140

Adaptive Evolution 140

CONCEPT 6.4 Long-term patterns of evolution are shaped by large-scale processes such as speciation, mass extinction, and adaptive radiation. 144 The Evolutionary History of Life 144

CONCEPT 6.5 Ecologicalinteractions and evolution exert a profound influence on one another. 148

Joint Effects of Ecology and Evolution 148 ACASESTUDYREVISITEDTrophy Hunting and Inadvertent

Evolution 151

CONNECTIONSIN NATUREThe Human Impact on

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UNIT

2

Populations

CHAPTER

7

Life History

Nemo Grows Up: A Case Study

Introduction 157

156

156

CONCEPT 7.1 Lifehistory patterns vary within and among species. 157

Life History Diversity 157

CONCEPT 7.2 Reproductive patterns can be classifiedalong several continua. 164

Life History Continua 164

CONCEPT 7.3 There are trade-offs between life history traits. 167

Trade-Offs 167

CONCEPT 7.4 Organisms face different selection pressures at different life cycle stages. 170

Life Cycle Evolution 170

ACASESTUDYREVISITEDNemo Grows Up 173

CONNECTIONSINNATURETerritoriality,Competition, and LifeHistory 174

CHAPTER

8

Population Distribution and

Abundance

177

From Kelp Forest to Urchin Barren: A Case StudyI 177 Introduction 178

CONCEPT 8.1 Populations are dynamic entities that vary in size over time and space. 178

Populations 178

CONCEPT 8.2 The distributions and abundances of organismsare limited by habitat suitability,historical factors, and dispersa!. 182

Distribution and Abundance 182

CONCEPT 8.3 Many species have a patchy distribution of populations across their geographic range. 186 Geographic Range 186

CONCEPT 8.4 The dispersion of individualswithin a population depends on the location of essential resources, competition, dispersal, and behavioral interactions. 188

Dispersion within Populations 188

CONCEPT 8.5 Population abundances and distributions can be estimated with area-based counts, distance methods, mark-recapture studies, and niche modeling. 190

Estimating Abundances and Distributions 190 ECOLOGICALTOOLKIT8.1 Estimating Abundance 191

ACASESTUDY REVISITEDFromKelp Forest to Urchin Barren 194

CONNECTIONSIN NATUREFromUrchinsto Ecosystems 196

CHAPTER

9

Population Growth and

Regulation

199

Human Population Growth: A Case Study 199

Introduction 200

CONCEPT 9.1 Lifetables show how survivaland reproductive rates vary with age, size, or life cycle stage. 201

Life Tables 201

.CONCEPT9.2 Lifetable data canbe used to project

the future age structure, size, and growth rate of a population. 204

Age Structure 204

CONCEPT 9.3 Populations can grow exponentially when conditions are favorable, but exponential growth cannot continue indefinitely. 207

Exponential Growth 207

ECOLOGICALTOOLKIT9.1 Estimating Population Growth Rates in a Threatened Species 208

CONCEPT 9.4 Population size can be determined by density-dependent and density-independent

factors. 211 .

Effects of Density 211

CONCEPT 9.5 The logisticequation incorporates limitsto growth and shows how a population may stabilize at a maximumsize,the carrying capacity. 214

Logistic Growth 214

A CASESTUDYREVISITEDHumanPopulationGrowth 216

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CHAPTER

10

Population Dynamics

221

A Sea in Trouble: A Case Study 221 Introduction 222

CONCEPT 10.1 Populations exhibit a wide range of growth patterns, ineluding exponential growth, logisticgrowth, fluctuations, and regular cyeles. 223

Patterns of Population Growth 223

CONCEPT 10.2 Delayed density dependence can cause populations to fluctuate in size. 226

Delayed Density Dependence 226

UNIT 3

Interactions among Organisms

CHAPTER

11

Competition

242

Competition in Plants That Eat Animals: A Case

Study 242 Introduction 243

CONCEPT 11.1 Competition occurs between individuals of two species that share the use of a resource that limits their growth, survival,or reproduction. 243

Competition for Resources 243

CONCEPT 11.2 Competition, whether direct or indirect, can limitthe distributions and abundances of competing species. 246

General Features of Competition 246

CONCEPT 11.3 Competing species are more likelyto coexist when they use resources in different ways. 249

Competitive Exclusion 249

ECOLOGICALTOOLKIT11.1 Isocline Analyses 252

CONCEPT 11.4 The outcome of competition can be altered by environmental conditions, species interactions, disturbance, and evolution. 254

Altering the Outcome of Competition 254

A CASESTUDYREVISITEDCompetitionin PlantsThatEat

Animals 257

CONNECTIONSINNATUREThe Paradoxof Diversity 258

CONCEPT 10.3 The risk of extinction increases greatly in small populations. 229

Population Extinction 229

CONCEPT 10.4 Many species have a metapopulation structure in which sets of spatially isolated populations are linked by dispersal. 234

Metapopulations 234

A CASESTUDYREVISITEDA Seain Trouble 237

CONNECTIONSIN NATUREFromBottom to Top, and Back Again 237

CHAPTER

12

Predation and

Herbiyory

262

Snowshoe Hare Cycles: A Case Study 262

Introduction 263

CONCEPT 12.1 Most predators have broad diets, whereas a majorityofherbivores have relatively narrow diets. 264

Predators and Herbivores 264

CONCEPT12.2 Organismshaveevolveda widerangeof

adaptations that help them obtain food and avoid being eaten. 266

Adaptations to Exploitative Interactions 266

CONCEPT 12.3 Predation and herbivory can affect

ecological communities greatly, in some cases causing a

shiftfrom onecommunitytype to another. 271

Effects of Exploitation on Communities 271

CONCEPT 12.4 Population cyeles can be caused by exploitative interactions. 275

Exploitation and Population Cycles 275

A CASESTUDYREVISITEDSnowshoeHareCycles 278

CONNECTIONSIN NATUREFrom Fearto Hormonesto Population Dynamics 280

CHAPTER

13

Parasitism

283

Enslaver

Parasites: ACase Study 283

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CONCEPT 13.1 Parasitestypicallyfeed on only one or a few host individuals. 285

Parasite Natural History 285

CONCEPT 13.2 Hosts have adaptations for defending themselves against parasites, and parasites have adaptations for overcoming host defenses. 287 Defenses and Counterdefenses 287

CONCEPT 13.3 Host and parasite populations can evolve together, each in response to selection pressure imposed by the other. 290

Parasite-Host Coevolution 290

CONCEPT 13.4 Parasitescan reduce the sizesof host pop-ulations and alter the outcomes of species interactions, thereby causingcommunitiesto change. 293 Ecological Effects of Parasites 293

CONCEPT 13.5 Simple models ofhost-pathogen dynamics suggest ways to control the establishment and spread of diseases. 297

Dynamics and Spread of Diseases 297 ACASESTUDYREVISITEDEnslaverParasites 301

CONNECTIONSINNATUREFromChemicalsto Evolutionand Ecosystems 302

UNIT4

Cornrnunities

CHAPTER

15

The Nature of

Communities

324

"Killer AIgae !": A Case Study 324 Introduction 325

CONCEPT 15.1 Communitiesare groups of interacting species that occur together at the same place and time. 325

What Are Communities? 325

CONCEPT 15.2 Species diversity and species composition are important descriptors of community

structure. 328

Community Structure 328

CONCEPT 15.3 Communities can be characterized by complex networks of direct and indirect interactions that vary in strength and direction. 333

Interactions of MuItiple Species 333

ECOLOGICALTOOLKIT 15.1 Measurements oí Interaction Strength 337

CHAPTER

14

Mutualism and

Commensalism

305

The First Farmers: A Case Study 305

Introduction 306

CONCEPT 14.1 In positive interactions, neither species is harmed and the benefits of the interaction are greater than the costs for at least one species. 306

Positive Interactions 306

CONCEPT 14.2 Each partner in a mutualistic interaction acts in ways that serve its own ecological and evolutionary interests. 313

Characteristics of Mutualism 313

CONCEPT 14.3 Positive interactions affect the abundances and distributions of populations as well as the composition of ecological communities. 316 Ecological Consequences of Positive

Interactions 316

A CASESTUDYREVISITEDThe FirstFarmers 319 CONNECTIONSIN NATUREFromMandibles to Nutrient

Cycling 320

A CASESTUDYREVISITED"KillerAlgae!" 340

CONNECTIONSIN NATUREStopping InvasionsRequires Commitment 340

CHAPTER

16

Change in

Communities

343

A Natural Experiment of Mountainous Proportions: A Case Study 343

Introduction 344

CONCEPT 16.1 Agents of change act on communities across all temporal and spatial scales. 345

Agents of Change 345

CONCEPT 16.2 Successionis the process of change in species composition over time as a result of abiotic and biotic agents of change. 347

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CONCEPT 16.3 Experimentalwork on succession shows its mechanismsto be diverse and context-dependent. 351

Mechanisms of Succession 351

CONCEPT 16.4 Communitiescan followdifferent

successionalpaths and display alternative states. 357 Altemative Stable States 357

A CASE STUDY REVISITED A Natural Experiment of

Mountainous Proportions 359

CONNECTIONSINNATUREPrimarySuccessionand Mutualism 361

CHAPTER

17

Biogeography

364

The Largest Ecological Experiment on Earth: A Case Study 364

Introduction 365

CONCEPT 17.1 Patterns of species diversity and distribution vary at global, regional, and local spatial scales. 365 Biogeography and Spatial Scale 365

CONCEPT 17.2 Global patterns of species diversity and composition are influenced by geographic area and isolation,evolutionary history, and global climate. 371

Global Biogeography 371

CONCEPT 17.3 Regionaldifferences in species diversity are influenced by area and distance, which determine the balance between immigrationand extinction rates. 378

Regional Biogeography 378

ECOLOGICALTOOLKIT17.1 Species-Area Curves 380

UNIT

5

Ecosystems

CHAPTER

19

Production

410

Life in the Deep Blue Sea, How Can It Be?: A Case Study 410

Introduction 411

CONCEPT 19.1 Energyin ecosystems originates with primary production by autotrophs. 412

Primary Production 412

A CASE STUDY REVISITEDThe Largest Ecological Experiment on Earth 384

CONNECTIONS IN NATURE Tropical Rainforest Diversity

BenefitsHumans 385

CHAPTER

18

Species Diversityin

Communities

388

Powered by Prairies? Biodiversity and Biofuels: A Case

Study 388

Introduction 389

CONCEPT 18.1 Species diversity differs among communities due to variation in regional species pools, abiotic conditions, and species interactions. 389

Community Membership 389

CONCEPT 18.2 Resource partitioning among the species in a community reduces competition and increases species diversity. 393

Resource Partitioning 393

CONCEPT 18.3 Processes such as disturbance, stress, predation, and positive interactions can mediate resource availability,thus promoting species coexistence and species diversity. 396

Processes That Promote Coexistence 396

CONCEPT 18.4 Many expe'riments show that species diversity is positively related to community function. 402

The Consequences of Diversity 402

A CASESTUDYREVISITEDPoweredby Prairies?Biodiversity and Biofuels 405

CONNECTIONSIN NATUREBarriersto Biofuels:The PlantCell

Wall Conundrum 406

ECOLOGICALTOOLKIT19.1 Remote Sensing 416

CONCEPT 19.2 Net primary production is constrained by

both physicaland biotic environmental factors. 418

Environmental Controls on NPP 418

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CONCEPT 19.4 Secondary production is generated through the consumption of organic matter by heterotrophs. 424

Secondary Production 424

A CASESTUDYREVISITEDLifein the Deep BlueSea, How Can It Be? 425

CONNECTIONSINNATUREEnergy-DrivenSuccessionand Evolutionin Hydrothermal Vent Communities 426

CHAPTER

20

Energy Flow and Food Webs 430

Toxinsin Remote Places:A Case Study 430 Introduction 431

CONCEPT 20.1 Trophic levels describe the feeding positions of groups of organismsin ecosystems. 431 Feeding Relationships 431

CONCEPT 20.2 The amount of energy transferred from one trophic level to the next depends on food quality and consumer abundance and physiology. 433

Energy Flow among Trophic Levels 433

CONCEPT 20.3 Changes in the abundances of organismsat one trophic level can influence energy flow at multiple trophic levels. 438

Trophic Cascades 438

CONCEPT 20.4 Food webs are conceptual models of the trophic interactions of organismsin an ecosystem. 442

FoodWebs 442

ACASESTUDYREVISITEDToxinsin Remote Places 448 CONNECTIONSIN NATUREBiologicalTransport of

Pollutants 449

CHAPTER

21

Nutrient Supply and

Cycling

452

A Fragile Crust: A Case Study 452

Introduction 453

CONCEPT 21.1 Nutrients enter ecosystems through the chemicalbreakdown of minerals in rocks or through fixationof atmospheric gases. 454

Nutrient Requirements and Sources 454

CONCEPT 21.2 Chemicaland biologicaltransformations in ecosystems alter the chemicalform and supply of nutrients. 458

Nutrient Transformations 458

CONCEPT 21.3 Nutrients cycle repeatedly through the components of ecosystems. 461

Nutrient Cyc1esand Losses 461 ECOLOGICALTOOLKIT21.1 Instrumenting

Catchments 465

CONCEPT 21.4 Freshwater and marine ecosystems receive

nutrient inputs from terrestrial ecosystems. 467 Nutrients in Aquatic Ecosystems 467

A CASESTUDYREVISITEDA FragileCrust 470

CONNECTIONSIN NATURENutrients, Disturbance, and

. InvasiveSpecies 471

UNIT 6

Applied and Large-Scale Ecology

CHAPTER

22

Conservation Biology

476

Can Birds and Bombs Coexist?: A Case Study 476

Introduction 477

CONCEPT 22.1 Conservation biology is an integrative discipline that applies the principIes of ecology to the conservation of biodiversity. 477

Conservation Biology 477

CONCEPT 22.2 Biodiversityis declining globally. 480 Dec1ining Biodiversity 480

CONCEPT 22.3 Primarythreats to biodiversity include habitat loss,invasivespecies, overexploitation, pollution, disease, and climate change. 484

Threats to Biodiversity 484

CONCEPT 22.4 Conservation biologists use many tools and work at multiple scalesto manage declining

populations. 490

Approaches to Conservation 490

ECOLOGICALTOOLKIT22.1Forensics in Conservation

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CONCEPT 22.5 Prioritizingspecies helps maximizethe biodiversity that can be protected with limited resources. 495

Ranking Species for Protection 495

A CASESTUDYREVISITEDCan Birdsand Bombs Coexist? 497 CONNECTIONSINNATURESome BurningQuestions 498

CHAPTER

23

Landscape Ecology

and Ecosystem

Management

501

W olves in the Yellowstone Landscape: A Case Study 501

Introduction 502

ECOlOGICAlTOOlKIT23.1 Geographic Information Systems (GIS) 503

CONCEPT 23.1 Landscape ecology examinesspatial patterns and their relationship to ecological processes and changes. 504

Landscape Ecology 504

CONCEPT 23.2 Habitat lossand fragmentation decreases habitat area, isolates populations, and alters conditions at habitat edges. 508

Habitat Loss and Fragmentation 508

CONCEPT 23.3 Biodiversitycan best be sustained by large reserves connected across the landscape and buffered from areas of intense human use. 514

Designing Nature Reserves 514

CONCEPT 23.4 Ecosystemmanagement is a collaborative process with the maintenance of long-term ecological integrity as its core value. 518

Ecosystem Management 518

A CASESTUDYREVISITEDWolves in the Yellowstone Landscape 520

CONNECTIONSIN NATURE Future Changes in the Yellowstone

Landscape 521

CHAPTER

24

Global Ecology

525

Dust Storms of Epic Proportions: A Case Study 525

Introduction 526

CONCEPT 24.1 Elementsmove among geologic,

atmospheric, oceanic, and biological pools at a global scale. 526

Global Biogeochemical Cycles 526

CONCEPT 24.2 Earth is warming due to anthropogenic emissionsof greenhouse gases. 532

Global Climate Change 532

CONCEPT 24.3 Anthropogenic emissionsof sulfur and nitrogen cause acid deposition, alter soil chemistry,and affect the health of ecosystems. 539

Acid and Nitrogen Deposition 539

CONCEPT 24.4 Lossesof ozone in the stratosphere and i"'creasesin ozone in the troposphere each pose risks to organisms. 543

Atmospheric Ozone 543

A CASESTUDYREVISITEDDust Storms of Epic Proportions 546

CONNECTIONS IN NATURE Dust as a Vector of Ecological

Impacts 548

Appendix 551

Answers to Figure Legend and Review Questions 553

Glossary 575

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