Ecology: Global Insights and Investigations

Peter Stiling
Release at: 2012
Pages: 659
First Edition
File Size: 114 MB
File Type: pdf
Language: English

Description of Ecology Global Insights and Investigations

In completing this Ecology book I am especially grateful to the many reviewers who graciously gave of their time in reading chapters. These folks are listed below. A great many other people also helped me immensely. A massive thanks to Joni Fraser, my developmental editor who made numerous suggestions, both large and small, from better examples, additional photographs, and reorganization to simple wordsmithing. 

Danny Meldung helped locate some great photographs and carefully hunted for more when a selection didn’t “wow” me. Fran Schreiber and Marge Kemp at McGraw-Hill provided help from major advice on themes to minor help with house-keeping issues. The design of the book and its cover was an immediate hit with all of us and for that, I thank Laurie Janssen, the designer. Sheila Frank, lead project manager, helped organize this team. Finally, thanks to Janice Roerig-Blong for believing in this project.

I would appreciate feedback on the text, be it art, narrative, or end-of-chapter material. If you know of a better example than the ones I have provided, please feel free to let me know. If there are good data sets to use at the end of chapter material or better multiple-choice questions, I’d be pleased to hear about them. I will continue combing the latest literature to keep the book current.

Content of Ecology Global Insights and Investigations

1 An Introduction to Ecology 2

1.1 Ecology: The Study of Living
Interactions 4
1.2 The Scale of Ecology: From
Organisms to Ecosystems 5
1.2.1 Organismal ecology investigates how individuals’
adaptations and choices affect their reproduction
and survival 5
1.2.2 Population ecology describes how populations
grow and interact with other species 6
1.2.3 Community ecology focuses on factors that
influence the number of species in area 7
1.2.4 Ecosystems ecology describes the passage of
energy and nutrients through communities 7
1.3 The Four Main Elements of Global Change 7
1.3.1 Element 1: Habitat destruction reduces available
habitat for wildlife 8
1.3.2 Element 2: Invasive species can cause extinctions
of native species 10
Feature Investigation  Secretion of Chemicals Gives
Some Invasive Plants a Competitive Edge 10
1.3.3 Element 3: Direct exploitation decreases the
the density of populations 11
1.3.4 Element 4: Pollution may cause global change via
climate alterations 12
Global Insight Biological Control Agents May Have
Strong Nontarget Effects 13
1.4 Ecological Methods: Observation,
Experimentation, and Analysis 14
1.4.1 Experimentation involves manipulating a
system and comparing results to an unmanipulated
control 16
1.4.2 Experiments can be performed in a laboratory or
in the field, or can result from natural phenomena 17
1.4.3 Meta-analysis allows data from similar
experiments to be combined 18
1.4.4 Mathematical models can describe ecologically
phenomena and predict patterns 19
Summary 20

SECTION ONE Organismal Ecology 22

2  Population Genetics 24
2.1 Evolution Concerns How
Species Change over Time 26
2.1.1 Charles Darwin proposed the
theory of evolution by natural selection 26
2.1.2 Alfred Russel Wallace was
co-discoverer of evolutionary theory 28
Global Insight Pollution Affects Color in the
Peppered Moth, Biston betularia 28
2.1.3 Gregor Mendel performed classic experiments on
the inheritance of traits 30
2.2 Gene and Chromosome Mutations Cause Novel
Phenotypes 31
2.2.1 Gene mutations involve changes in the sequence
of nucleotide bases 32
2.2.2 Chromosome mutations alter the order of
genes 33
2.3 The Hardy-Weinberg Equation Describes Allele
and Genotype Frequencies in an Equilibrium
Population 33
2.4 Small Populations Cause
the Loss of Genetic Diversity 35
2.4.1 Inbreeding is mating between closely related
individuals 35
Feature Investigation Inbreeding Increases the Risk
of Extinction 36
2.4.2 Genetic drift refers to random changes in allele
frequencies over time 38
2.4.3 Knowledge of effective population sizes is vital to
conservation efforts 40
Summary 41
Test Yourself 41
Conceptual Questions 42
Data Analysis 43

3  Natural Selection, Speciation and Extinction 44

3.1 Natural Selection Can
Follow One of Four Different
Pathways 46
3.1.1 Directional selection favors phenotypes at one
extreme 46
3.1.2 Stabilizing selection favors intermediate
phenotypes 47
3.1.3 Balancing selection promotes genetic
diversity 48
Feature Investigation John Losey and Colleagues
Demonstrated That Balancing Selection by Opposite
Patterns of Parasitism and Predation Can Maintain
Different-Colored Forms of Aphids 48
3.1.4 Disruptive selection favors the survival of two
phenotypes 50
3.2 Speciation Occurs Where Genetically Distinct
Groups Separate into Species 50
3.2.1 There are many definitions of what constitutes a
species 51
Global Insight Hybridization and Extinction 53
3.2.2 The main mechanisms of speciation are allopatric
speciation and sympatric speciation 54
3.3 Evolution Has Accompanied Geologic Changes on
Earth 54
3.3.1 Early life caused changes in atmospheric oxygen
and carbon dioxide 56
3.3.2 The evolution of multicellular organisms also
accompanied atmospheric changes 56
3.3.3 Modern distribution patterns of plants and
animals have been influenced by continental
drift 59
3.4 Many Patterns Exist in the Formation and
Extinction of Species 63
3.4.1 Species formation may be gradual or sporadic 64
3.4.2 Patterns of extinction are evident from the fossil
record 65
3.4.3 Current patterns of extinction have been
influenced by humans 65
3.4.4 Extinction rates are higher on islands than on the
mainland 66
3.4.5 Extinctions are most commonly caused by
introduced species and habitat destruction 67
3.5 Degree of Endangerment Varies by
Taxa, Geographic Location, and Species
Characteristics 67
3.5.1 Endangered species are not evenly distributed
among geographical areas 69
3.5.2 Vulnerability to extinction can be linked to
species characteristics 70
Summary 72
Test Yourself 73
Conceptual Questions 73
Data Analysis 73

4  Behavioral Ecology 74

4.1 Altruism: Behavior That Benefits
Others at Personal Cost 76
4.1.1 In nature, individual selfish
behavior is more likely than altruism 76
4.1.2 Altruistic behavior is often associated with kin
selection 78
4.1.3 Altruism in social insects arises partly from
genetics and partly from lifestyle 79
4.1.4 Unrelated individuals may behave altruistically if
reciprocation is likely 80
4.2 Group Living Has Advantages and
Disadvantages 82
4.2.1 Living in groups may increase prey vigilance 82
4.2.2 Living in groups offers protection by the “selfish
herd” 83
Feature Investigation  Reto Zach Showed How Large
Whelks Are the Optimum Prey Size for Crows 84
4.3 Foraging Behavior: The Search for Food 85
4.3.1 Optimal foraging maximizes the benefits and
minimizes the costs of food gathering 85
Global Insight  The North Atlantic Oscillation Affects
Snow Pack, Wolf Behavior, and Moose Predation
Rates 86
4.3.2 Defending territories have costs and benefits 86
4.3.3 Game theory establishes whether individuals fight
for resources or flee from opponents 88
4.4 Mating Systems Range from Monogamous to
Polygamous 90
4.4.1 In promiscuous mating systems, each male or
female may mate with multiple partners 91
4.4.2 In monogamous mating systems, males and
females are paired for at least one reproductive
season 91
4.4.3 In polygynous mating systems, one male mates
with many females 92
4.4.4 In polyandrous mating systems, one female mates
with many males 93
4.4.5 Sexual selection involves mate choice and mate
competition 94
Summary 97
Test Yourself 97
Conceptual Questions 98
Data Analysis 98

SECTION TWO Physiological Ecology 100

5 Temperature 102

5.1 The Effects of Cold
Temperatures, Especially
Freezing, Are Severe 104
5.1.1 Freezing temperatures are lethal for many plants
species 106
5.1.2 Animal body size changes in different
temperatures 108
5.2 Hot Temperatures Limit Many Species’
Distributions 108
5.2.1 Some species depend on fire for their
existence 110
5.2.2 Temperature extremes may be more critical than
temperature averages 110
5.2.3 Wind can amplify the effects of temperature of 112
5.3 The Greenhouse Effect Causes the Earth’s
Temperature to Rise 112
Global Insight  Global Warming Is Changing Species
Phenologies 116
Feature Investigation Rachel Hickling and
Colleagues Showed the Northerly Limits of a
Wide Range of Taxonomic Groups Are Shifting
Poleward 117
Summary 118
Test Yourself 119
Data Analysis 119
Conceptual Questions 120

6 Water 122

6.1 Water Availability Affects
Organismal Abundance 124
6.2 Salt Concentrations in Soil and
Water Can Be Critical 128
Global Insight Global Warming May Alter Future
Global Precipitation Patterns 129
6.3 Soil and Water pH Affect the Distribution of
Organisms 131
Feature Investigation Ralph Hames and Colleagues
Showed How Acid Rain Has Affected the Distribution
of the Wood Thrush in North America 134
Summary 136
Test Yourself 136
Conceptual Questions 136
Data Analysis 137

7 Nutrients 138

7.1 Soil Development Affects
Nutrient Levels 140
7.2 Plant Growth Is Limited by a
Variety of Nutrients 142
Feature Investigation Christopher Clark and David
Tilman Showed How Low-Level Nitrogen Deposition
Has Reduced the Number of Species in Midwest
Prairies 144
Global Insight  Polluted Areas May Be Restored Using
Living Organisms 146
7.3 Herbivore Populations Are Limited by Plant
Nutrient Levels 146
7.4 Light Can Be a Limiting Resource for Plants 147
7.5 Carbon Dioxide and Oxygen Availability Limit
Organismal Growth and Distributions 149
7.6 Species Distributions Are Often Limited by
Multiple Abiotic Factors 150
Summary 152
Test Yourself 152
Conceptual Questions 152
Data Analysis 153

SECTION THREE Population Ecology 154

8  Demographic Techniques and Population Patterns 156

8.1 A Variety of Techniques Are
Used to Quantify Population
Density 158
8.2 Patterns of Spacing May Be Clumped, Uniform, or
Random 161
8.3 Fragmented Habitats Affect Spatial
Dispersion 163
Global Insight  Habitat Destruction Has Radically
Changed the Dispersion Patterns of Many
Species 164
8.4 Landscape Ecology Concerns the Spatial
Arrangement of Habitats and Organisms 165
8.5 Metapopulations Are Separate Populations That
Mutually Affect One Another via Dispersal 167
Feature Investigation  Joshua Tewksbury Showed
How Connecting Habitat Patches via Corridors
Facilitated Plant and Animal Movement 168
Summary 171
Test Yourself 171
Conceptual Questions 171

9  Life Tables and Demography 172

9.1 Age Distributions, Life Tables,
and Survivorship Curves
Summarize Survival Patterns 174
9.1.1 Age distributions reflect survival and mortality
patterns 174
9.1.2 Static life tables provide a snapshot of a
population’s age structure from a sample at a given
time 174
9.1.3 Cohort life tables follow an entire cohort of
individuals from birth to death 177
9.1.4 Survivorship curves present survival data
graphically 177
Feature Investigation Frederick Barkalow, Jr., and
Colleagues Constructed a Cohort Life Table for the
Eastern Gray Squirrel 178
Global Insight Hunting, Overcollecting, and Grazing
Can Greatly Affect Survivorship Curves 181
9.2 Age-Specific Fertility Data Can Tell Us When to
Expect Population Growth to Occur 182
Summary 184
Test Yourself 185
Conceptual Questions 185
Data Analysis 186

10  Population Growth 188

10.1 Unlimited Population Growth
Leads to J-shaped Population
Growth Curves 190
10.1.1 Geometric growth describes population growth
for periodic breeders 190
10.1.2 Exponential growth describes the population
growth for continuous breeders 193
Global Insight Population Growth May Change in
Response to Global Warming 195
10.2 Limited Resources Lead to S-Shaped Population
Growth Curves 197
10.2.1 Logistic growth results in an upper limit to
population size 197
10.2.2 Time lags can influence whether
or not a population reaches an upper limit 199
10.3 Density-Dependent Factors May Limit Population
Size 202
10.4 Life History Strategies Incorporate Traits Relating
to Survival and Competitive Ability 205
10.4.1 Reproductive strategies include reproduction in
a single event or continuous breeding 205
10.4.2 r and K selection represent two different life
history strategies 206
10.4.3 Grime’s triangle is an alternative to r and K
selection 207
10.4.4 Population viability analysis uses life history data
to predict extinction probability 208
10.5 Human Population Growth 209
10.5.1 Human population growth
fi ts an exponential pattern 209
10.5.2 Knowledge of a population’s age structure helps
predict future growth 210
10.5.3 Human population fertility rates vary
worldwide 210
Feature Investigation Concept of an Ecological
Footprint Helps Estimate Carrying Capacity 212
Summary 214
Test Yourself 215
Conceptual Questions 215
Data Analysis 216

SECTION FOUR Species Interactions 218

11  Competition and Coexistence 220

11.1 Several Different Types
of Competition Occur in
Nature 222
11.2 The Outcome of Competition Can Vary
with Changes in the Biotic and Abiotic
Environments 223
Feature Investigation Connell’s Experiments
with Barnacle Species Show That One Species
Can Competitively Exclude Another in a Natural
Setting 224
11.3 Field Studies Show Interspecific Competition
Occurs Frequently 226
11.3.1 Invasive species may outcompete native
species 229
Global Insight  Invasive Rusty Crayfish Have
Outcompeted Many Native North American
Crayfish 231
11.3.2 Competition may occur between biological
control agents 231
11.4 The Winners and Losers of Competitive
Interactions May Be Predicted Using
Mathematical Models 234
11.4.1 The Lotka-Volterra competition models are
based on the logistic equation of population
growth 234
11.4.2 Tilman’s R* models predict the outcome of
competition based on resource use 236
11.5 Species May Coexist If They Do Not Occupy
Identical Niches 238
11.5.1 Species may partition resources, promoting
coexistence 239
11.5.2 Morphological differences may allow species to
coexist 241
Summary 244
Test Yourself 244
Conceptual Questions 245
Data Analysis 245

12  Facilitation 246

12.1 Mutualism Is an Association
between Two Species That
Benefits Both Species 248
12.1.1 Dispersive mutualism involves dispersal of
pollen and seeds 249
12.1.2 Defensive mutualism involves one species
defending another in return for a reward 252
12.1.3 Resource-based mutualism involves species that
can better obtain resources together than alone 254
Global Insight  The Mutualistic Relationships of
Humans with Crops and Livestock Have Produced
Dramatic Environmental Changes 256
12.1.4 Some mutualisms may be endosymbiotic, where
one species lives in the body of another 258
12.1.5 Mutualisms are not easily modeled
mathematically 258
12.2 Commensal Relationships Are Those in Which
One Partner Receives a Benefit While the Other Is
Unaffected 259
12.3 Facilitation May Be More Common under
Conditions of Environmental Stress 261
Feature Investigation Calloway’s Experiments Show
How Positive Interactions among Alpine Plants
Increase with Environmental Stress 262
Summary 263
Test Yourself 263
Conceptual Questions 264
Data Analysis 265

13  Predation 266

13.1 Animals Have Evolved Many
Antipredator Adaptations 268
13.2 Predator-Prey Interactions May
Be Modeled by Lotka-Volterra Equations 271
13.3 Introduced Predators Show Strong Effects on
Native Prey 274
13.4 Native Prey Show Large Responses to
Manipulations of Native Predators 277
Feature Investigation Vredenburg’s Study Shows
That Native Prey Species May Recover after Removal
of Exotics 278
13.5 Humans, As Predators, Can Greatly Impact
Animal Populations 280
Global Insight  Predator-Prey Relationships May Be
Altered by Long-Term Climate Changes 281
Summary 285
Test Yourself 285
Conceptual Questions 286
Data Analysis 286

14  Herbivory 288

14.1 Plants Have a Variety
of Defenses Against
Herbivores 291
14.1.1 Mechanical defenses include spines and sticky
hairs 292
14.1.2 Chemical defenses include alkaloids, phenolics,
and terpenoids 292
Feature Investigation José Gómez and Regino
Zamora Showed That Thorns Are Induced by
Herbivory 292
14.1.3 Induced defenses are turned on by
herbivory 295
14.1.4 Chemical defense strategies change according
to plant type and environmental conditions 295
14.1.5 Additional plant defenses include production
of chemicals which mimic herbivore chemical
messengers 297
14.2 Herbivores May Overcome Plant Defenses and
Impact of Plant Populations 298
14.3 How Much Plant Material Do Herbivores
Consume? 300
Global Insight  Predator Removal in the United
States Has Resulted in Overgrazing by Native
Herbivores 302
14.4 Plants Can Have Strong Effects on Herbivore
Densities 305
Summary 307
Test Yourself 307
Conceptual Questions 308
Data Analysis 308

15  Parasitism 310

15.1 Parasites Exhibit a Wide
Range of Attributes and
Lifestyles 312
15.1.1 Parasites can be classified in many different
ways 313
15.1.2 Many parasite life cycles involve more than one
species of host 314
15.1.3 Kleptoparasitism involves one species stealing
resources from another 316
15.2 Hosts Have Evolved Many Different Types of
Defenses Against Parasites 316
15.3 Parasites Can Cause High Mortality in Host
Populations 317
15.3.1 Parasite-removal studies show how
native parasites strongly affect native host
populations 318
Feature Investigation Sylvia Hurtrez-Boussès and
Colleagues Microwaved Bird Nests to Eliminate Nest
Parasites 318
15.3.2 Invasive parasites may have even more
devastating effects than native parasites 320
15.3.3 Some nonnative parasites are introduced
deliberately for the biological control of pests 322
Global Insight  Rinderpest Caused Massive Mortality
in African Wildlife in the 19th Century 323
15.4 Host-Parasite Models Are Different from
Predator-Prey Models 324
15.5 Parasitism May Be Increased by Climate
Change 325
Summary 326
Test Yourself 327
Conceptual Questions 327
Data Analysis 328

16  Population Regulation 330

16.1 Both Top-Down and Bottom-Up
Effects Are Important in Natural
Systems 332
16.2 Conceptual Models Suggest Top-Down and
Bottom-Up Effects Vary in Importance in
Different Environments 336
Global Insight  Urbanization Can Change the Relative
Effects of Top-Down and Bottom-Up Factors 339
16.3 Key Factor Analysis and Indispensable Mortality
Are Two Techniques Used to Compare the
Strengths of Mortality Factors 340
16.3.1 Key factors are those which cause most of the
change in population densities 340
16.3.2 Indispensable mortality measures the amount of
mortality from one factor that cannot be replaced by
mortality from another factor 343
Feature Investigation Munir and Sailer Used
Key Factor Analysis to Examine the Success of an
Imported Biological Control Agent 344
Summary 347
Test Yourself 347
Conceptual Questions 348
Data Analysis 348

SECTION FIVE Community Ecology 350

17  Species Diversity 352

17.1 The Nature of Communities
Has Been Debated by
Ecologists 354
17.2 A Variety of Indices Have Been Used to Estimate
Species Biodiversity 355
17.2.1 Dominance indices are more influenced by the
numbers of common species 355
17.2.2 Information statistic indices are more influenced
by the numbers of rare species 357
Feature Investigation Stuart Marsden’s Field
Studies in Indonesia Showed How Logged Forests
Have a Lower Bird Diversity Than Unlogged
Forests 358
17.2.3 Weighted indices attempt to assess the relative
importance of species in a community 361
17.2.4 Regional diversity incorporates diversity at many
sites 362
17.2.5 Evenness is a measure of how
diverse a community is relative
to the maximum possible diversity 363
17.2.6 The effective number of species is a conceptually appealing measure of diversity 364
17.3 Rank Abundance Diagrams Visually Describe
the Distribution of Individuals Among Species in
Communities 365
17.3.1 The lognormal distribution is based on statistical
properties of data 365
17.3.2 Tokeshi’s niche apportionment models provide
biological explanations for rank abundance
plots 366
17.4 Community Similarity Is a Measure of How
Many Species Are Common Between
Communities 369
Summary 370
Test Yourself 371
Conceptual Questions 371
Data Analysis 371

18  Species Richness Patterns 372

18.1 The Species-Time Hypothesis
Suggests Communities
Diversify with Age 375
18.2 The Species-Area Hypothesis Suggests Large
Areas Support More Species 377
18.3 The Species-Energy Hypothesis Suggests That
Greater Productivity Permits the Existence of
More Species 378
18.4 The Intermediate Disturbance Hypothesis
Suggests Species Richness Is Highest in Areas of
Intermediate Levels of Disturbance 379
18.5 Natural Enemies Promote Increased Species
Richness at Local Levels 380
18.6 Communities in Climatically Similar Habitats May
Themselves Be Similar in Species Richness 381
Global Insight Species Richness Could Be Reduced
by Changing Climate 382
18.7 Habitat Conservation Focuses on Identifying
Countries Rich in Species or Habitats 384
Summary 388
Test Yourself 388
Conceptual Questions 389
Data Analysis 389

19  Species Richness and Community Services 390

19.1 Five Hypotheses Explain How
Species Richness Affects
Community Services 393
19.1.1 Recent studies have investigated the
relationship between species richness and
community function 394
Feature Investigation Shahid Naeem’s Ecotron
Experiments Showed a Relationship Between
Species Richness and Community Services 394
19.1.2 Plant species richness affects herbivore and
predator species richness 396
19.1.3 Increased natural enemy species richness
increases herbivore suppression 397
19.1.4 The sampling effect is the likely cause
of increased performance in species-rich
communities 398
Global Insight  Overfishing Reduces Fish Species
Richness and Increases the Prevalence of Coral
Disease 399
19.2 Species-Rich Communities Are More Stable Than
Species-Poor Communities 399
19.2.1 A stable community changes little in species
richness over time 400
19.2.2 The diversity-stability hypothesis states that
species-rich communities are more stable than
species-poor communities 401
19.2.3 Species richness affects community resistance to
invasion by introduced species 402
19.2.4 Invasive species may possess a variety of special
life-history traits 406
Summary 409
Test Yourself 410
Conceptual Questions 410
Data Analysis 410

20 Succession 412

20.1 Several Mechanisms That
Describe Succession Have
Been Proposed 414
20.1.1 Facilitation assumes each invading species
creates more favorable habitat for succeeding
species 415
Feature Investigation  Peter Vitousek and Colleagues
Showed How Invasion by an Exotic Tree Changed
Soil Nitrogen Levels in Hawaii 417
20.1.2 Inhibition implies that early colonists prevent
later arrivals from replacing them 418
20.1.3 Tolerance suggests that early colonists neither
facilitate nor inhibit later colonists 418
20.1.4 Facilitation and inhibition may both occur in the
the same community during succession 419
20.2 Species Richness Often Increases During
Succession 421
Global Insight The Pathway of Succession Has Been
Changed by a Variety of Human Activities 422
20.3 Restoration Ecology Is Guided by the Theory of
Succession 424
Summary 426
Test Yourself 426
Conceptual Questions 427
Data Analysis 427

21  Island Biogeography 428

21.1 The Theory of Island
Biogeography Considers
Succession on Islands 430
21.1.1 The species-area hypothesis describes the effect
of island size on species richness 432
21.1.2 The species-distance hypothesis describes the
effect of island distance on species richness 435
Global Insight  Deforestation and the Loss of
Species 436
21.1.3 Species turnover on islands is generally low 436
Feature Investigation  Simberloff and Wilson’s
Experiments Tested the Predictions of Island
Biogeography Theory 438
21.2 Nature Reserve Designs Incorporate Principles of
Island Biogeography and Landscape Ecology 440
Summary 442
Test Yourself 443
Conceptual Questions 443
Data Analysis 444

SECTION SIX Biomes 446

22 Terrestrial Biomes 448

22.1 Variation in Solar Radiation
Determines the Climate
in Different Areas of the
World 450
22.2 Terrestrial Biome Types Are Determined by
Climate Patterns 456
Global Insight  Tropical Deforestation Threatens Many
Species with Extinction 460
Global Insight  Anthropogenic Biomes of the
World 476
Summary 478
Test Yourself 478
Conceptual Questions 479

23 Marine Biomes 480

23.1 Variations in Ocean Current
and Tidal Range 482
23.1.1 Ocean currents are created
by winds and the Earth’s rotation 482
23.1.2 Waves are also created by the wind 483
23.1.3 Langmuir circulation may carry material deep
below the water surface 484
23.1.4 Deep-ocean currents are caused by
thermohaline circulation 484
23.1.5 Tides are caused by the gravitational pull of the
moon and the sun 484
Global Insight  The Effects of Sea Level Rise on
Coastal Regions 487
23.2 Marine Biomes Are Determined by Water
Temperature, Depth, and Wave Action 488
Summary 498
Test Yourself 498
Conceptual Questions 499

24 Freshwater Biomes 500

24.1 The Properties of Freshwater
Vary Dramatically with
Temperature 502
Global Insight  Aquatic Fauna in the U.S. Are
Threatened by Global Change 505
24.2 Freshwater Biomes Are Determined by Variations
in Temperature, Light Availability, Productivity,
and Oxygen Content 506
Summary 514
Test Yourself 515
Conceptual Questions 515

SECTION SEVEN Ecosystems Ecology 516

25  Food Webs and Energy Flow 518

25.1 The Main Organisms within
Food Chains Are Termed
Producers, Primary Consumers, and Secondary
Consumers 520
25.2 In Most Food Webs, Chain Lengths Are Short and
a Pyramid of Numbers Exists 525
25.2.1 Consumption, assimilation, and production
efficiencies are measures of ecological
efficiency 525
25.2.2 Trophic-level transfer efficiency measures energy
fl ow between trophic levels 526
25.2.3 Ecological pyramids describe the distribution
of numbers, biomass, or energy between trophic
levels 526
25.2.4 In most food webs connectance decreases with
increasing numbers of species 528
Feature Investigation  Gary Polis Showed How Real-
World Food Webs Are Complex 528
25.3 Within Food Webs Some Species Have
Disproportionately Large Effects 530
Global Insight Some Invasive Species May Be
Viewed as Cultural Keystone Species 534
Summary 534
Test Yourself 535
Conceptual Questions 535
Data Analysis 536

26  Biomass Production 538

26.1 Production Is Infl uenced by
Water, Temperature, Nutrients
and Light Availability 540
26.1.1 Net primary production in terrestrial ecosystems
is limited mainly by water, temperature, and nutrient
availability 542
26.1.2 Net primary production in aquatic ecosystems
is limited mainly by light and nutrient
availability 543
Global Insight  Elevated Atmospheric CO 2 Increases
Primary Productivity 544
26.1.3 Net primary production varies in different
biomes 546
26.1.4 Secondary production is generally limited by
available primary production 548
26.2 Decomposition Is Increased by High
Temperatures, Soil Moisture, and Soil
Nutrients 550
Feature Investigation John Teal Mapped Out
Energy Flow in a Georgia Salt Marsh 550
26.3 Living Organisms Can Affect Nutrient
Availability 556
Summary 559
Test Yourself 559
Conceptual Questions 560
Data Analysis 560

27  Biogeochemical Cycles 562

27.1 Biogeochemical Cycles Transfer
Elements Among the Biotic
and Abiotic Components of
Ecosystems 564
27.2 Phosphorus Cycles Locally Between Geological
and Biological Components of Ecosystems 564
Global Insight  Biomagnification of Pesticides Can
Occur in Higher Trophic Levels 566
27.3 Carbon Cycles Among Biological, Geological, and
Atmospheric Pools 568
Feature Investigation  Stiling and Drake’s
Experiments with Elevated Co 2 Show an Increase in
Plant Growth but a Decrease in Herbivory 570
27.4 The Nitrogen Cycle Is Strongly Influenced by
Biological Processes That Transform Nitrogen into
Usable Forms 572
27.5 The Sulfur Cycle Is Heavily Influenced by
Anthropogenic Effects 574
27.6 The Water Cycle Is Largely a Physical Process of
Evaporation and Precipitation 576
Summary 578
Test Yourself 578
Conceptual Questions 579
Data Analysis 579
Appendix A Answer Key A-1
Glossary G-1
References R-1
Credits C-1
Index I-1

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