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Elements of Ecology Eighth Edition Thomas M. Smith University of Virginia Robert Leo Smith West Virginia University, Emeritus Editor-in-Chief: Beth Wilbur Executive Director of Development: Deborah Gale Senior Acquisitions Editor: Star MacKenzie Project Editor: Leata Holloway Assistant Editor: Frances Sink Media Producer: Lee Ann Doctor Executive Marketing Manager: Lauren Harp Executive Managing Editor: Erin Gregg Managing Editor: Michael Early Senior Production Project Manager: Shannon Tozier Production Management and Compositor: Integra-Chicago Illustrations: Scientific Illustrators Text and Cover Design: tt eye Manufacturing Buyer: Michael Penne Senior Photo Editor: Donna Kalal Photo Research: Kristin Piljay Cover Printer: Lehigh-Phoenix Color, Hagerstown Printer and Binder: R.R. Donnelley, Willard Cover Photo Credit: Chris Martin Bahr / Photo Researchers, Inc.: Weaver Ants (Oecophylla sp.) on leaf. Credits and acknowledgments borrowed from other sources and reproduced, with permission, in this textbook appear on the appropriate page within the text or on pp. C-1–C-8. Copyright © 2012, 2009, 2006 Pearson Education, Inc., publishing as Pearson Benjamin Cummings. All rights reserved. Manufactured in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. To obtain permission(s) to use material from this work, please submit a written request to Pearson Education, Inc., Permissions Department, 1900 E. Lake Ave., Glenview, IL 60025. For information regarding permissions, call (847) 486-2635. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and the publisher was aware of a trademark claim, the designations have been printed in initial caps or all caps. Pearson Benjamin Cummings is a trademark, in the U.S. and/or other countries, of Pearson Education, Inc. or its affiliates. Library of Congress Cataloging-in-Publication Data Smith, T. M. (Thomas Michael) Elements of ecology / Thomas M. Smith, Robert Leo Smith.—8th ed. p. cm. Includes bibliographical references and index. ISBN 978-0-321-73607-9 1. Ecology. I. Smith, Robert Leo. II. Title. QH541.S624 2011 577—dc22 2011015962 ISBN 10: 0-321-73607-9; ISBN 13: 978-0-321-73607-9 (Student edition) ISBN 10: 0-321-74286-9; ISBN 13: 978-0-321-74286-5 (Professional copy) ISBN 10: 0-321-88454-X; ISBN 13: 978-0-321-88454-1 (Books a la Carte) 2 3 4 5 6 7 8 9 10—DOW—15 14 13 12 11 Contents Preface xv Chapter 1 The Nature of Ecology 1 1.1 Ecology Is the Study of the Relationship between Organisms and Their Environment 2 1.2 Organisms Interact with the Environment in the Context of the Ecosystem 2 ECOLOGICAL ISSUES: Ecology Has Complex Roots 3 1.3 1.4 1.5 Ecological Systems Form a Hierarchy 4 Ecologists Study Pattern and Process at Many Levels 5 Ecologists Investigate Nature Using the Scientific Method 6 QUANTIFYING ECOLOGY 1.1: Classifying Ecological Data 8 1.6 Models Provide a Basis for Predictions 9 QUANTIFYING ECOLOGY 1.2: Displaying Ecological Data: Histograms and Scatter Plots 10 1.7 Uncertainty Is an Inherent Feature of Science 12 1.8 Ecology Has Strong Ties to Other Disciplines 12 1.9 The Individual Is the Basic Unit of Ecology 13 Summary 13 • Study Questions 14 • Further Readings 14 PART 1 The Physical Environment 16 Chapter 2 Climate 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 18 Earth Intercepts Solar Radiation 19 Intercepted Solar Radiation Varies Seasonally 21 Air Temperature Decreases with Altitude 22 Air Masses Circulate Globally 25 Solar Energy, Wind, and Earth’s Rotation Create Ocean Currents 26 Temperature Influences the Moisture Content of Air 27 Precipitation Has a Distinctive Global Pattern 27 Topography Influences Regional and Local Patterns of Precipitation 30 Irregular Variations in Climate Occur at the Regional Scale 30 Most Organisms Live in Microclimates 32 ECOLOGICAL ISSUES: Urban Microclimates 33 Summary 34 • Study Questions 35 • Further Readings Chapter 3 35 The Aquatic Environment 36 3.1 Water Cycles between Earth and the Atmosphere 37 ECOLOGICAL ISSUES: Groundwater Resources 38 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Water Has Important Physical Properties 39 Light Varies with Depth in Aquatic Environments 41 Temperature Varies with Water Depth 42 Water Functions as a Solvent 44 Oxygen Diffuses from the Atmosphere to the Surface Waters 45 Acidity Has a Widespread Influence on Aquatic Environments 46 Water Movements Shape Freshwater and Marine Environments 47 iii 3.9 Tides Dominate the Marine Coastal Environment 48 3.10 The Transition Zone between Freshwater and Saltwater Environments Presents Unique Constraints 49 Summary Chapter 4 50 • Study Questions 51 • Further Readings 51 The Terrestrial Environment 52 4.1 Life on Land Imposes Unique Constraints 53 4.2 Plant Cover Influences the Vertical Distribution of Light 54 QUANTIFYING ECOLOGY 4.1: Beer’s Law and the Attenuation of Light 56 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 Soil Is the Foundation upon Which All Terrestrial Life Depends 57 The Formation of Soil Begins with Weathering 58 Soil Formation Involves Five Interrelated Factors 58 Soils Have Certain Distinguishing Physical Characteristics 59 The Soil Body Has Horizontal Layers, or Horizons 60 Moisture-Holding Capacity Is an Essential Feature of Soils 61 Ion Exchange Capacity Is Important to Soil Fertility 62 Basic Soil Formation Processes Produce Different Soils 63 Summary 65 • Study Questions 66 • Further Readings 67 PART 2 The Organism and Its Environment 68 Chapter 5 Ecological Genetics: Adaptation and Natural Selection 70 5.1 Adaptations Are a Product of Natural Selection 71 5.2 Genes Are the Units of Inheritance 72 5.3 The Phenotype Is the Physical Expression of the Genotype 72 5.4 Genetic Variation Occurs at the Level of the Population 73 5.5 Adaptation Is a Product of Evolution by Natural Selection 73 5.6 Several Processes Can Function to Alter Patterns of Genetic Variation 77 QUANTIFYING ECOLOGY 5.1: Hardy–Weinberg Principle 78 5.7 5.8 Natural Selection Can Result in Genetic Differentiation 80 Adaptations Reflect Trade-offs and Constraints 81 FIELD STUDIES: Beren Robinson 82 5.9 Organisms Respond to Environmental Variation at the Individual and Population Levels 86 ECOLOGICAL ISSUES: The Ecology of Antibiotic Resistance 88 Summary 89 • Study Questions 90 • Further Readings 90 Chapter 6 Plant Adaptations to the Environment 92 6.1 Photosynthesis Is the Conversion of Carbon Dioxide into Simple Sugars 93 6.2 The Light a Plant Receives Affects Its Photosynthetic Activity 94 6.3 Photosynthesis Involves Exchanges between the Plant and Atmosphere 95 6.4 Water Moves from the Soil, through the Plant, to the Atmosphere 95 6.5 The Process of Carbon Uptake Differs for Aquatic and Terrestrial Plants 98 6.6 Plant Temperatures Reflect Their Energy Balance with the Surrounding Environment 98 6.7 Carbon Gained in Photosynthesis Is Allocated to the Production of Plant Tissues 99 6.8 Constraints Imposed by the Physical Environment Have Resulted in a Wide Array of Plant Adaptations 101 iv 6.9 Species of Plants Are Adapted to Different Light Environments 101 QUANTIFYING ECOLOGY 6.1: Relative Growth Rate 104 6.10 The Link between Water Demand and Temperature Influences Plant Adaptations 106 FIELD STUDIES: Kaoru Kitajima 108 6.11 Plants Vary in Their Response to Environmental Temperatures 112 6.12 Plants Exhibit Adaptations to Variations in Nutrient Availability 113 6.13 Wetland Environments Present Unique Constraints on Plant Adaptations 115 Summary Chapter 7 116 • Study Questions 118 • Further Readings 118 Animal Adaptations to the Environment 119 7.1 Size Imposes a Fundamental Constraint on the Evolution of Organisms 120 7.2 Animals Have Various Ways of Acquiring Energy and Nutrients 122 7.3 Animals Have Various Nutritional Needs 125 7.4 Mineral Availability Affects Animal Growth and Reproduction 126 7.5 Animals Require Oxygen to Release Energy Contained in Food 127 FIELD STUDIES: Martin Wikelski 128 7.6 Regulation of Internal Conditions Involves Homeostasis and Feedback 130 7.7 Animals Exchange Energy with Their Surrounding Environment 130 QUANTIFYING ECOLOGY 7.1: Heat Exchange and Temperature Regulation 132 7.8 Animals Fall into Three Groups Relative to Temperature Regulation 133 7.9 Poikilotherms Depend on Environmental Temperatures 134 7.10 Homeotherms Escape the Thermal Restraints of the Environment 135 7.11 Endothermy and Ectothermy Involve Trade-offs 136 7.12 Heterotherms Take on Characteristics of Ectotherms and Endotherms 138 7.13 Torpor Helps Some Animals Conserve Energy 138 7.14 Some Animals Use Unique Physiological Means for Thermal Balance 139 7.15 Maintenance of Water Balance for Terrestrial Animals Is Constrained by Uptake and Conservation 140 7.16 Animals of Aquatic Environments Face Unique Problems in Maintaining Water Balance 141 7.17 Buoyancy Helps Aquatic Organisms to Stay Afloat 142 7.18 Daily and Seasonal Light and Dark Circles Influence Animal Activity 142 7.19 Critical Day Lengths Trigger Seasonal Responses 143 7.20 Activity Rhythms of Intertidal Organisms Follow Tidal Cycles 144 Summary 145 • Study Questions 147 • Further Readings 147 PART 3 Populations 148 Chapter 8 Properties of Populations 150 8.1 8.2 8.3 8.4 8.5 8.6 Organisms May Be Unitary or Modular 151 The Distribution of a Population Defines Its Spatial Location 151 Abundance Reflects Population Density and Distribution 153 Determining Density Requires Sampling 156 Populations Have Age Structures 156 Sex Ratios in Populations May Shift with Age 158 v 8.7 Individuals Move Within the Population 158 8.8 Population Distribution and Density Change in Both Time and Space 160 ECOLOGICAL ISSUES: Human-Assisted Dispersal 162 Summary 163 • Study Questions 163 • Further Readings Chapter 9 164 Population Growth 165 9.1 Population Growth Reflects the Difference between Rates of Birth and Death 166 QUANTIFYING ECOLOGY 9.1: Derivatives and Differential Equations 167 QUANTIFYING ECOLOGY 9.2: Exponential Model of Population Growth 168 9.2 Life Tables Provide a Schedule of Age-Specific Mortality and Survival 169 9.3 Different Types of Life Tables Reflect Different Approaches to Defining Cohorts and Age Structure 170 QUANTIFYING ECOLOGY 9.3: Life Expectancy 171 9.4 Life Tables Provide Data for Mortality and Survivorship Curves 172 9.5 Birthrate Is Age-Specific 173 9.6 Birthrate and Survivorship Determine Net Reproductive Rate 174 9.7 Age-Specific Mortality and Birthrates Can Be Used to Project Population Growth 174 9.8 Stochastic Processes Can Influence Population Dynamics 176 9.9 A Variety of Factors Can Lead to Population Extinction 177 9.10 Small Populations Are Susceptible to Extinction 177 Summary Chapter 10 178 • Study Questions 179 • Further Readings 179 Life History 181 10.1 The Evolution of Life Histories Involves Trade-offs 182 10.2 Reproduction Involves Both Benefits and Costs to Individual Fitness 182 10.3 Age at Maturity Is Influenced by Patterns of Age-Specific Mortality 183 10.4 Reproductive Effort Is Governed by Trade-offs between Fecundity and Survival 185 10.5 There Is a Trade-off between the Number and Size of Offspring 188 QUANTIFYING ECOLOGY 10.1: Interpreting Trade-offs 190 10.6 Species Differ in the Timing of Reproduction 190 10.7 An Individual’s Life History Represents the Interaction between Genotype and the Environment 192 10.8 Mating Systems Describe the Pairing of Males and Females 193 10.9 Acquisition of a Mate Involves Sexual Selection 194 10.10 Females May Choose Mates Based on Resources 195 FIELD STUDIES: Alexandra L. Basolo 196 10.11 Patterns of Life History Characteristics Reflect External Selective Forces 198 Summary Chapter 11 200 • Study Questions 201 • Further Readings 201 Intraspecific Population Regulation 202 11.1 The Environment Functions to Limit Population Growth 203 ECOLOGICAL ISSUES: The Human Carrying Capacity 204 11.2 Population Regulation Involves Density Dependence 206 QUANTIFYING ECOLOGY 11.1: The Logistic Model of Population Growth 207 11.3 vi Competition Results When Resources Are Limited 207 11.4 Intraspecific Competition Affects Growth and Development 208 11.5 Intraspecific Competition Can Influence Mortality Rates 210 11.6 Intraspecific Competition Can Reduce Reproduction 212 FIELD STUDIES: T. Scott Sillett 214 11.7 11.8 11.9 11.10 11.11 11.12 High Density Is Stressful to Individuals 216 Dispersal Can Be Density Dependent 216 Social Behavior May Function to Limit Populations 217 Territoriality Can Function to Regulate Population Growth 217 Plants Preempt Space and Resources 219 Density-Independent Factors Can Influence Population Growth 219 Summary Chapter 12 220 • Study Questions 221 • Further Readings 222 Metapopulations 223 12.1 Four Conditions Define a Metapopulation 224 12.2 Metapopulation Dynamics Is a Balance between Colonization and Extinction 226 QUANTIFYING ECOLOGY 12.1: Equilibrium Proportion of Occupied Patches 227 12.3 Patch Area and Isolation Influence Metapopulation Dynamics 227 12.4 Habitat Heterogeneity Influences Local Population Persistence 230 12.5 Some Habitat Patches May Function as the Major Source of Emigrants 230 12.6 Certain Factors Can Function to Synchronize the Dynamics of Local Populations 231 12.7 Species Differ in Their Potential Rates of Colonization and Extinction 232 12.8 The Concept of Population Is Best Approached by Using a Hierarchical Framework 233 Summary 234 • Study Questions 235 • Further Readings 235 PART 4 Species Interactions 236 Chapter 13 Species Interactions, Population Dynamics, and Natural Selection 238 13.1 Species Interactions Can Be Classified Based on Their Reciprocal Effects 239 13.2 Species Interactions Influence Population Dynamics 240 13.3 Species Interactions Can Function as Agents of Natural Selection 241 13.4 The Nature of Species Interactions Can Vary Across Geographic Landscapes 245 13.5 Species Interactions Can Be Diffuse 245 13.6 Species Interactions Influence the Species’ Niche 246 13.7 Species Interactions Can Drive Adaptive Radiation 248 Summary Chapter 14 249 • Study Questions 249 • Further Readings 250 Interspecific Competition 251 14.1 Interspecific Competition Involves Two or More Species 252 14.2 There Are Four Possible Outcomes of Interspecific Competition 252 14.3 Laboratory Experiments Support the Lotka–Volterra Equations 253 QUANTIFYING ECOLOGY 14.1: Interpreting Population Isoclines 255 14.4 Studies Support the Competitive Exclusion Principle 256 14.5 Competition Is Influenced by Nonresource Factors 256 vii 14.6 Temporal Variation in the Environment Influences Competitive Interactions 257 FIELD STUDIES: Katherine N. Suding 258 14.7 Competition Occurs for Multiple Resources 260 14.8 Relative Competitive Abilities Change along Environmental Gradients 261 QUANTIFYING ECOLOGY 14.2: Competition under Changing Environmental Conditions: Application of the Lotka–Volterra Model 263 14.9 Interspecific Competition Influences the Niche of a Species 266 14.10 Coexistence of Species Often Involves Partitioning Available Resources 267 14.11 Competition Is a Complex Interaction Involving Biotic and Abiotic Factors 270 Summary Chapter 15 270 Predation • Study Questions 271 • Further Readings 272 273 15.1 Predation Takes a Variety of Forms 274 15.2 Mathematical Model Describes the Basics of Predation 274 15.3 Model Suggests Mutual Population Regulation 276 15.4 Functional Responses Relate Prey Consumed to Prey Density 277 15.5 Predators Respond Numerically to Changing Prey Density 280 15.6 Foraging Involves Decisions about the Allocation of Time and Energy 281 QUANTIFYING ECOLOGY 15.1: A Simple Model of Optimal Foraging 283 15.7 15.8 15.9 15.10 15.11 15.12 Foragers Seek Productive Food Patches 284 Risk of Predation Can Influence Foraging Behavior 285 Coevolution Can Occur between Predator and Prey 285 Animal Prey Have Evolved Defenses against Predators 285 Predators Have Evolved Efficient Hunting Tactics 289 Herbivores Prey on Autotrophs 289 FIELD STUDIES: Rick A. Relyea 290 15.13 Plants Have Evolved Characteristics That Deter Herbivores 292 15.14 Plants, Herbivores, and Carnivores Interact 294 15.15 Predators Influence Prey Dynamics through Lethal and Nonlethal Effects 294 Summary Chapter 16 296 • Study Questions 297 • Further Readings 297 Parasitism and Mutualism 298 16.1 Parasites Draw Resources from Host Organisms 299 16.2 Hosts Provide Diverse Habitats for Parasites 300 16.3 Direct Transmission Can Occur between Host Organisms 300 16.4 Transmission between Hosts Can Involve an Intermediate Vector 301 16.5 Transmission Can Involve Multiple Hosts and Stages 301 16.6 Hosts Respond to Parasitic Invasions 301 16.7 Parasites Can Affect Host Survival and Reproduction 303 16.8 Parasites May Regulate Host Populations 303 16.9 Parasitism Can Evolve into a Mutually Beneficial Relationship 305 16.10 Mutualisms Involve Diverse Species Interactions 305 ECOLOGICAL ISSUES: Plagues Upon Us 306 16.11 Mutualisms Are Involved in the Transfer of Nutrients 307 FIELD STUDIES: John J. Stachowicz 308 viii 16.12 16.13 16.14 16.15 Some Mutualisms Are Defensive 311 Mutualisms Are Often Necessary for Pollination 311 Mutualisms Are Involved in Seed Dispersal 312 Mutualisms Can Influence Population Dynamics 313 QUANTIFYING ECOLOGY 16.1: A Model of Mutualistic Interactions 314 Summary 315 • Study Questions 316 • Further Readings 316 PART 5 Community Ecology 318 Chapter 17 Community Structure 320 17.1 The Number of Species and Their Relative Abundance Define Diversity 321 17.2 Numerical Supremacy Defines Dominance 323 17.3 Keystone Species Influence Community Structure Disproportionately to Their Numbers 323 17.4 Food Webs Describe Species Interactions 324 17.5 Species within a Community Can Be Classified into Functional Groups 324 17.6 Communities Have a Characteristic Physical Structure 326 17.7 Zonation Is Spatial Change in Community Structure 328 17.8 Defining Boundaries between Communities Is Often Difficult 329 17.9 Two Contrasting Views of the Community 331 QUANTIFYING ECOLOGY 17.1: Community Similarity 332 Summary 333 • Study Questions 334 • Further Readings 334 Chapter 18 Factors Influencing the Structure of Communities 335 18.1 18.2 The Fundamental Niche Constrains Community Structure 336 Species Interactions Are Diffuse 337 FIELD STUDIES: Sally D. Hacker 338 18.3 Food Webs Illustrate Indirect Interactions 340 QUANTIFYING ECOLOGY 18.1: Quantifying the Structure of Food Webs: Connectance 341 18.4 Food Webs Suggest Controls of Community Structure 344 18.5 Species Interactions along Environmental Gradients Involve Both Stress Tolerance and Competition 345 18.6 Environmental Heterogeneity Influences Community Diversity 348 18.7 Resource Availability Can Influence Plant Diversity within a Community 349 Summary Chapter 19 351 • Study Questions 352 • Further Readings 352 Community Dynamics 353 19.1 Community Structure Changes Through Time 354 ECOLOGICAL ISSUES: American Forests 356 19.2 Primary Succession Occurs on Newly Exposed Substrates 358 19.3 Secondary Succession Occurs after Disturbances 358 19.4 The Study of Succession Has a Rich History 360 19.5 Succession Is Associated with Autogenic Changes in Environmental Conditions 361 19.6 Species Diversity Changes during Succession 363 19.7 Succession Involves Heterotrophic Species 364 19.8 Systematic Changes in Community Structure Are a Result of Allogenic Environmental Change at a Variety of Timescales 365 ix 19.9 Community Structure Changes over Geologic Time 367 19.10 The Concept of Community Revisited 369 Summary Chapter 20 371 • Study Questions 372 • Further Readings 373 Landscape Dynamics 374 20.1 Environmental Processes Create a Variety of Patches in the Landscape 375 20.2 Transition Zones Offer Diverse Conditions and Habitats 377 20.3 Patch Size and Shape Are Crucial to Species Diversity 378 20.4 The Theory of Island Biogeography Applies to Landscape Patches 382 20.5 Landscape Connectivity Permits Movement between Patches 384 20.6 The Metapopulation and Metacommunity Are Central Concepts in the Study of Landscape Dynamics 385 20.7 Frequency, Intensity, and Scale Determine the Impact of Disturbances 385 FIELD STUDIES: Nick M. Haddad 386 20.8 Various Natural Processes Function as Disturbances 388 20.9 Human Disturbance Creates Some of the Most Long-Lasting Effects 390 20.10 The Landscape Represents a Shifting Mosaic of Changing Communities 391 Summary 391 • Study Questions 392 • Further Readings 393 PART 6 Ecosystem Ecology 394 Chapter 21 Ecosystem Energetics 396 21.1 The Laws of Thermodynamics Govern Energy Flow 397 21.2 Energy Fixed in the Process of Photosynthesis Is Primary Production 397 21.3 Temperature, Water, and Nutrients Control Primary Production in Terrestrial Ecosystems 398 21.4 Temperature, Light, and Nutrients Control Primary Production in Aquatic Ecosystems 401 21.5 External Inputs of Organic Carbon Can Be Important in Aquatic Ecosystems 403 21.6 Energy Allocation and Plant Life-Form Influence Primary Production 404 21.7 Primary Productivity Varies with Time 405 21.8 Primary Productivity Limits Secondary Production 406 ECOLOGICAL ISSUES: Human Appropriation of Net Primary Productivity 408 21.9 Consumers Vary in Efficiency of Production 408 21.10 Ecosystems Have Two Major Food Chains 410 21.11 Energy Flows through Trophic Levels Can Be Quantified 411 FIELD STUDIES: Brian Silliman 412 21.12 Consumption Efficiency Determines the Pathway of Energy Flow through the Ecosystem 414 21.13 Energy Decreases in Each Successive Trophic Level 415 Summary Chapter 22 416 • Study Questions 417 • Further Readings 417 Decomposition and Nutrient Cycling 419 22.1 Most Essential Nutrients Are Recycled within the Ecosystem 420 22.2 Decomposition Is a Complex Process Involving a Variety of Organisms 421 x 22.3 Studying Decomposition Involves Following the Fate of Dead Organic Matter 423 QUANTIFYING ECOLOGY 22.1: Estimating the Rate of Decomposition 424 22.4 Several Factors Influence the Rate of Decomposition 425 FIELD STUDIES: Edward A. G. (Ted) Schuur 428 22.5 Nutrients in Organic Matter Are Mineralized During Decomposition 430 22.6 Decomposition Proceeds as Plant Litter Is Converted into Soil Organic Matter 432 22.7 Plant Processes Enhance the Decomposition of Soil Organic Matter in the Rhizosphere 434 22.8 Decomposition Occurs in Aquatic Environments 434 22.9 Key Ecosystem Processes Influence the Rate of Nutrient Cycling 436 ECOLOGICAL ISSUES: Nitrogen Fertilizers 437 22.10 Nutrient Cycling Differs between Terrestrial and Open-Water Aquatic Ecosystems 438 22.11 Water Flow Influences Nutrient Cycling in Streams and Rivers 440 22.12 Land and Marine Environments Influence Nutrient Cycling in Coastal Ecosystems 441 22.13 Surface Ocean Currents Bring about Vertical Transport of Nutrients 443 Summary Chapter 23 443 • Study Questions 444 • Further Readings 445 Biogeochemical Cycles 446 23.1 There Are Two Major Types of Biogeochemical Cycles 447 23.2 Nutrients Enter the Ecosystem via Inputs 447 23.3 Outputs Represent a Loss of Nutrients from the Ecosystem 448 23.4 Biogeochemical Cycles Can Be Viewed from a Global Perspective 448 23.5 The Carbon Cycle Is Closely Tied to Energy Flow 448 23.6 Carbon Cycling Varies Daily and Seasonally 450 23.7 The Global Carbon Cycle Involves Exchanges among the Atmosphere, Oceans, and Land 451 23.8 The Nitrogen Cycle Begins with Fixing Atmospheric Nitrogen 452 23.9 The Phosphorus Cycle Has No Atmospheric Pool 454 23.10 The Sulfur Cycle Is Both Sedimentary and Gaseous 455 ECOLOGICAL ISSUES: Nitrogen Saturation 457 23.11 The Global Sulfur Cycle Is Poorly Understood 458 23.12 The Oxygen Cycle Is Largely under Biological Control 459 23.13 The Various Biogeochemical Cycles Are Linked 460 Summary 461 • Study Questions 462 • Further Readings 463 PART 7 Ecological Biogeography 464 Chapter 24 Terrestrial Ecosystems 466 24.1 Terrestrial Ecosystems Reflect Adaptations of the Dominant Plant Life-Forms 468 QUANTIFYING ECOLOGY 24.1: Climate Diagrams 470 24.2 Tropical Forests Characterize the Equatorial Zone 471 24.3 Tropical Savannas Are Characteristic of Semiarid Regions with Seasonal Rainfall 474 24.4 Grassland Ecosystems of the Temperate Zone Vary with Climate and Geography 476 24.5 Deserts Represent a Diverse Group of Ecosystems 479 24.6 Mediterranean Climates Support Temperate Shrublands 482 xi 24.7 Forest Ecosystems Dominate the Wetter Regions of the Temperate Zone 484 24.8 Conifer Forests Dominate the Cool Temperate and Boreal Zones 486 24.9 Low Precipitation and Cold Temperatures Define the Arctic Tundra 488 Summary Chapter 25 490 • Study Questions 492 • Further Readings 492 Aquatic Ecosystems 493 25.1 Lakes Have Many Origins 494 25.2 Lakes Have Well-Defined Physical Characteristics 494 ECOLOGICAL ISSUES: Dams: Regulating the Flow of River Ecosystems 496 25.3 The Nature of Life Varies in the Different Zones 497 25.4 The Character of a Lake Reflects Its Surrounding Landscape 498 25.5 Flowing-Water Ecosystems Vary in Structure and Types of Habitats 499 25.6 Life Is Highly Adapted to Flowing Water 501 QUANTIFYING ECOLOGY 25.1: Streamflow 502 25.7 The Flowing-Water Ecosystem Is a Continuum of Changing Environments 504 25.8 Rivers Flow into the Sea, Forming Estuaries 504 25.9 Oceans Exhibit Zonation and Stratification 506 25.10 Pelagic Communities Vary Among the Vertical Zones 507 25.11 Benthos Is a World of Its Own 508 25.12 Coral Reefs Are Complex Ecosystems Built by Colonies of Coral Animals 509 25.13 Productivity of the Oceans Is Governed by Light and Nutrients 510 Summary Chapter 26 511 • Study Questions 513 • Further Readings 513 Coastal and Wetland Ecosystems 514 26.1 The Intertidal Zone Is the Transition between Terrestrial and Marine Environments 515 26.2 Rocky Shorelines Have a Distinct Pattern of Zonation 515 26.3 Sandy and Muddy Shores Are Harsh Environments 517 26.4 Tides and Salinity Dictate the Structure of Salt Marshes 518 26.5 Mangroves Replace Salt Marshes in Tropical Regions 519 26.6 Freshwater Wetlands Are a Diverse Group of Ecosystems 520 26.7 Hydrology Defines the Structure of Freshwater Wetlands 523 ECOLOGICAL ISSUES: The Continuing Decline of the Wetlands 524 26.8 Freshwater Wetlands Support a Rich Diversity of Life 526 Summary Chapter 27 526 • Study Questions 527 • Further Readings 527 Large-Scale Patterns of Biological Diversity 528 27.1 Earth’s Biological Diversity Has Changed through Geologic Time 529 27.2 Past Extinctions Have Been Clustered in Time 530 27.3 Regional and Global Patterns of Species Diversity Vary Geographically 530 27.4 Species Richness in Terrestrial Ecosystems Correlates with Climate and Productivity 532 27.5 In Marine Environments, There Is an Inverse Relationship between Productivity and Diversity 533 27.6 Species Diversity Is a Function of Processes Operating at Many Scales 534 QUANTIFYING ECOLOGY 27.1: Quantifying Biodiversity: Comparing Species Richness Using Rarefaction Curves 535 Summary 536 • Study Questions 537 • Further Readings 537 xii PART 8 Human Ecology 538 Chapter 28 Population Growth, Resource Use, and Sustainability 540 28.1 Sustainable Resource Use Is a Balance between Supply and Demand 542 28.2 Sustainability Can Be Indirectly Limited by Adverse Consequences of Resource Use 544 28.3 Sustainability Is a Concept Learned from Natural Ecosystems 544 28.4 Agricultural Practices Vary in the Level of Energy Input 544 28.5 Swidden Agriculture Represents a Dominant Form of Agriculture in the Wet Tropics 545 28.6 Industrialized Agriculture Dominates the Temperate Zone 546 28.7 Different Agricultural Methods Represent a Trade-off between Sustainability and Productivity 548 28.8 Sustainable Agriculture Depends on a Variety of Methods 549 28.9 Sustainable Forestry Aims to Achieve a Balance between Net Growth and Harvest 551 FIELD STUDIES: Deborah Lawrence 552 28.10 Exploitation of Fisheries Has Lead to the Need for Management 556 28.11 Fisheries Management Requires an Ecosystem Approach 558 28.12 Economics Are a Key Factor Governing Resource Management 560 Summary Chapter 29 562 • Study Questions 564 • Further Readings 564 Habitat Loss, Biodiversity, and Conservation 565 29.1 Habitat Destruction Is the Leading Cause of Current Species Extinctions 566 29.2 Human-Introduced Invasive Species May Threaten Many Native Species 568 29.3 Species Differ in Their Susceptibility to Extinction 571 29.4 Identifying Threatened Species Is Critical to Conservation Efforts 572 29.5 Regions of High Species Diversity Are Crucial to Conservation Efforts 572 ECOLOGICAL ISSUES: Wolf Reintroduction, Restoration, and Management 575 29.6 Protecting Populations Is the Key To Conservation Efforts 576 29.7 Reintroduction Is Necessary to Reestablish Populations of Some Species 577 29.8 Habitat Conservation Functions to Protect Whole Communities 579 29.9 Habitat Conservation Involves Establishing Protected Areas 579 29.10 Habitat Restoration Is Often Necessary in Conservation Efforts 582 29.11 Environmental Ethics Is at the Core of Conservation 583 Summary Chapter 30 584 • Study Questions 585 • Further Readings 586 Global Climate Change 588 30.1 Greenhouse Gases Influence Earth’s Energy Balance and Climate 589 30.2 Atmospheric Concentration of Carbon Dioxide Is Rising 589 30.3 Tracking the Fate of CO2 Emissions 591 30.4 Atmospheric CO2 Concentrations Affect CO2 Uptake by Oceans 591 FIELD STUDIES: Erika Zavaleta 592 30.5 Plants Respond to Increased Atmospheric CO2 594 30.6 Greenhouse Gases Are Changing the Global Climate 596 xiii 30.7 Changes in Climate Will Affect Ecosystems at Many Levels 598 ECOLOGICAL ISSUES: Who Turned Up the Heat? 602 30.8 Changing Climate Will Shift the Global Distribution of Ecosystems 604 30.9 Global Warming Would Raise Sea Level and Affect Coastal Environments 605 30.10 Climate Change Will Affect Agricultural Production 606 30.11 Climate Change Will Directly and Indirectly Affect Human Health 607 30.12 Understanding Global Change Requires the Study of Ecology at a Global Scale 609 Summary References R-1 Glossary G-1 Credits C-1 Index I-1 xiv 610 • Study Questions 611 • Further Readings 612 Preface The first edition of Elements of Ecology appeared in 1976 as a short version of Ecology and Field Biology. Since that time, Elements of Ecology has evolved into a textbook intended for use in a one-semester introduction to ecology course. Although the primary readership will be students majoring in the life sciences, in writing this text we were guided by our belief that ecology should be part of a liberal education. We believe that students who major in such diverse fields as economics, sociology, engineering, political science, law, history, English, languages, and the like should have some basic understanding of ecology for the simple reason that it impinges on their lives. New for the Eighth Edition For those familiar with this text, you will notice a number of changes in this new edition of Elements of Ecology. In addition to updating many of the examples and topics to reflect the most recent research and results in the field of ecology, we have made a number of changes in the organization and content of the text. An important objective of the text is to use the concept of adaptation through natural selection as a framework for unifying the study of ecology, linking pattern and process across the hierarchical levels of ecological study: individual organisms, populations, communities, and ecosystems. Many of the changes made in previous editions have focused on this objective, and the changes to this edition continue to work toward this goal. Life History Patterns Chapter Returned to Part Three Despite all previous efforts, we feel that we did not fully meet this objective in the discussion of populations (Part Three) in the seventh edition. In hindsight, we believe that this shortcoming was a result of our decision to move the presentation of Life History from Part Three (Populations) to Part Two (The Organisms and Its Environment) in the sixth edition. By moving Life History to Part Two we were trying to maintain the theme of trade-offs and constraints in the evolution of characteristics that is developed in Chapter 6 (Plant Adaptations to the Environment) and Chapter 7 (Animal Adaptations to the Environment). However, it is the discussion of life histories, specifically the discussion of adaptations relating to age-specific patterns of survival and fecundity (reproduction), that provide a direct link between natural selection and population dynamics. For this reason, we have returned the chapter on Life History to Part Three (Populations). The chapter now follows Chapter 10 (Population Growth). In addition, we have revised the materials that are presented to make explicit the links between life history characteristics and population dynamics using the framework of life tables that is developed in Chapter 10 (Population Growth). Restructured Part Four: Species Interactions Another major change that we have introduced in the eighth edition to emphasize the concept of adaptation through natural selection as a framework for unifying the study of ecology is in the restructured presentation of Part Four, Species Interactions. In previous editions, Part Four consisted of three chapters that introduced the four major species interactions of competition, predation, parasitism, and mutualism (and the broader topic of facilitation). This format, however, did not provide a general framework for viewing the role of population interactions in the process of evolution by natural selection that is common to all species interactions—the process of coevolution. New Species Interactions Introductory Chapter To meet this need, we now open Part Four (Species Interactions) with a new chapter entitled Species Interactions, Population Dynamics, and Natural Selection. The objective of this new chapter is to introduce the variety of species interactions that occur among populations, and to explore how these interactions influence the respective populations (species) involved xv at two timescales: (1) the influence of species interactions on the processes of mortality and reproduction, which directly influence population dynamics, and (2) the role of species interaction as agents of natural selection by influencing the relative fitness of individuals within the population(s). The chapter provides a common framework for exploring the specific species interactions that are introduced in the chapters of Part Four that follow. Expanded Coverage of Key Ecological Topics Although the majority of this new edition retains the general structure of the seventh edition, we have added additional and expanded coverage of a wide variety of topics throughout the text including coevolution, metacommunities, landscape connectivity, sources of organic carbon in aquatic ecosystems, and the evolution of life history characteristics. Updated Research Results: Part Eight A historical feature of the Elements of Ecology text is our focus on applying the science of ecology to current environmental issues, providing students with a first-hand understanding of the importance of ecology in the relationship between the human population and the natural environment. Since publication of the seventh edition, advances have been made in our understanding of the issues that are presented in Part Eight: Human Ecology (Chapter 28: Population Growth, Resource Use, and Sustainability; Chapter 29: Habitat Loss, Biodiversity, and Conservation; and Chapter 30: Global Climate Change). In response, we have updated many of the research results presented in these chapters to reflect the most current understanding of these issues. Expanded Quantitative Features Ecology is a science rich in concepts, yet as with all science, it is quantitative. As such, a major objective of any science course should be the development of basic skills relating to the analysis and interpretation of empirical data. As with the seventh edition, the Quantifying Ecology feature in this new edition functions to provide students with an understanding of how concepts introduced in the chapters are quantified. In many chapters, the Quantifying Ecology boxes focus on assisting the reader with the interpretation of graphs, mathematical models, or quantitative methods that we have introduced within the main body of the text. In the seventh edition, however, we added an additional feature, Interpreting Ecological Data, to assist students in the development of quantitative skills. We have retained and expanded this feature in the eighth edition. Interpreting Ecological Data is associated directly with various figures and tables in the text. The feature consists of two or more questions relating directly to the interpretation of data and analyses presented in the associated figure or table. It has become a common practice in many new textbooks to embellish figures and tables with annotations that function to provide the reader with an interpretation of the graph or data. Although we also use this technique for a number of complex graphics, our annotations are meant only as an extension of the figure or table captions. Rather, we believe that it is better to ask specific questions that will both encourage and assist the reader in the interpretation and understanding of the data and analyses that are presented. In doing so we hope to assist the reader in building the basic skills that are necessary to move beyond the examples presented in the text and begin to explore the wealth of ecological studies published in the books and journals that are referenced throughout the text. It is our belief that the development of these basic quantitative and interpretative skills are as important as understanding the body of concepts presented in the text that form the framework of the science of ecology. The answers to the questions presented in the Interpreting Ecological Data features are provided at the associated website. Structure and Content The structure and content of the text is guided by our basic belief that: (1) the fundamental unit in the study of ecology is the individual organism, and (2) the concept of adaptation through natural selection provides the framework for unifying the study of ecology at higher levels of organization: populations, communities, and ecosystems. A central theme of the text is the concept of trade-offs—that the set of adaptations (characteristics) that enable an organism to survive, grow, and reproduce under one set of environmental conditions inevitably impose constraints on its ability to function (survive, grow, and reproduce) equally well under different environmental conditions. These environmental conditions include both the physical environment as well as xvi the variety of organisms (both the same and different species) that occupy the same habitat. This basic framework provides a basis for understanding the dynamics of populations at both an evolutionary and demographic scale. The text begins with an introduction to the science of ecology in Chapter 1 (The Nature of Ecology). The remainder of the text is divided into eight parts. Part One examines the constraints imposed on living organisms by the physical environment, both aquatic and terrestrial. Part Two begins by examining how these constraints imposed by the environment function as agents of change through the process of natural selection, the process through which adaptations evolve. The remainder of Part Two explores specific adaptations of organisms to the physical environment, considering both organisms that derive their energy from the sun (autrotrophs) and those that derive their energy from the consumption and break-down of plant and animal tissues (heterotrophs). Part Three examines the properties of populations, with an emphasis on how characteristics expressed at the level of the individual organisms ultimately determine the collective dynamics of the population. As such, population dynamics are viewed are a function of life history characteristics that are a product of evolution by natural selection. Part Four extends our discussion from interactions among individuals of the same species to interactions among populations of different species (interspecific interactions). In these chapters we expand our view of adaptations to the environment from one dominated by the physical environment, to the role of species interactions in the process of natural selection and on the dynamics of populations. Part Five explores the topic of ecological communities. This discussion draws upon topics covered in Parts Two through Four to examine the factors that influence the distribution and abundance of species across environmental gradients, both spatial and temporal. Part Six combines the discussions of ecological communities (Part Five) and the physical environment (Part One) to develop the concept of the ecosystem. Here the focus is on the flow of energy and matter through natural systems. Part Seven continues the discussion of communities and ecosystems in the context of biogeography, examining the broad-scale distribution of terrestrial and aquatic ecosystems, as well as regional and global patterns of biological diversity. Part Eight focuses on the interactions between humans and ecological systems. It is here that we examine the important current environmental issues relating to population growth, sustainable resource use, declining biological diversity, and global climate change. The objective of these chapters is to explore the role of the science of ecology in both understanding and addressing these critical environmental issues. Throughout the text we explore this range of topics by drawing upon current research in the various fields of ecology, providing examples that enable the reader to develop an understanding of species natural history, the ecology of place (specific ecosystems), and the basic process of science. Associated Materials • Instructor’s Resource DVD (0-321-74290-7) • Instructor Guide (0-321-74288-5) • Computerized Test Bank (0-321-74289-3) • Ecology Place Companion Website (www.ecologyplace.com) • Course Management Options (All CourseCompass and Blackboard courses offer preloaded content including tests, quizzes, and more.) Acknowledgments No textbook is a product of the authors alone. The material this book covers represents the work of hundreds of ecological researchers who have spent lifetimes in the field and the laboratory. Their published experimental results, observations, and conceptual thinking provide the raw material out of which the textbook is fashioned. We particularly acknowledge and thank the fourteen ecologists that are featured in the Field Studies boxes. Their cooperation in providing artwork and photographs is greatly appreciated. xvii Revision of a textbook depends heavily on the input of users who point out mistakes and opportunities. We took these suggestions seriously and incorporated most of them. We are deeply grateful to the following reviewers for their helpful comments and suggestions on how to improve this edition: Judith Bramble, DePaul University William Brown, SUNY Fredonia Steve Blumenshine, Fresno State University Mike Farabee, Estrella Mountain Community College Sue Hum-Musser, Western Illinois University Gerlinde Hoebel, University of Wisconsin, Milwaukee Jacob Kerby, University of South Dakota Ned J. Knight, Linfield College David Pindel, Corning Community College B.K Robertson, Alabama State University Erik P. Scully, Towson University Daniela Shebitz, Kean University Neal J. Voelz, St. Cloud State University Reviewers of Previous Editions: Peter Alpert, University of Massachusetts John Anderson, College of the Atlantic Morgan Barrows, Saddleback College Paul Bartell, Texas A&M University Christopher Beck, Emory University Nancy Broshot, Linfield College Chris Brown, Tennessee Tech University Evert Brown, Casper College David Bybee, Brigham Young University, Hawaii Dan Capuano, Hudson Valley Community College Brian Chabot, Cornell University Mitchell Cruzan, Portland State University Robert Curry, Villanova University Richard Deslippe, Texas Tech University Darren Divine, Community College of Southern Nevada Curt Elderkin, The College of New Jersey Lauchlan Fraser, University of Akron Sandi Gardner, Triton College E. O. Garton, University of Idaho Frank Gilliam, Marshall University xviii Brett Goodwin, University of North Dakota James Gould, Princeton University Mark C. Grover, Southern Utah University Mark Gustafson, Texas Lutheran University Greg Haenel, Elon University William Hallahan, Nazareth College Douglas Hallett, Northern Arizona University Gregg Hartvigsen, State University of New York at Geneseo Floyd Hayes, Pacific Union College Michael Heithaus, Florida International University Jessica Hellman, Notre Dame University Jason Hoeksema, University of California at Santa Cruz John Jaenike, University of Rochester John Jahoda, Bridgewater State University Stephen Johnson, William Penn University Doug Keran, Central Lakes Community College Jeff Klahn, University of Iowa Jamie Kneitel, California State University, Sacramento Frank Kuserk, Moravian College Kate Lajtha, Oregon State University Vic Landrum, Washburn University James Lewis, Fordham University Richard Lutz, Rutgers University Richard MacMillen, University of California at Irvine Ken R. Marion, University of Alabama, Birmingham Deborah Marr, Indiana University at South Bend Chris Migliaccio, Miami Dade Community College Don Miles, Ohio University L. Maynard Moe, California State University, Bakersfield Sherri Morris, Bradley University Steve O’Kane, University of Northern Iowa Matthew Parris, University of Memphis James Refenes, Concordia University Seith Reice, University of North Carolina Ryan Rehmeir, Simpson College Rick Relyea, University of Pittsburgh Carol Rhodes, College of San Mateo Eric Ribbens, Western Illinois University xix Robin Richardson, Winona State University Thomas Rosburg, Drake University Tatiana Roth, Coppin State College Irene Rossell, University of North Carolina, Asheville Rowan Sage, University of Toronto Nathan Sanders, University of Tennessee Thomas Sarro, Mount Saint Mary College Maynard Schaus, Virginia Wesleyan College Wendy Sera, University of Maryland Mark Smith, Chaffey College Paul Snelgrove, Memorial University of Newfoundland Amy Sprinkle, Jefferson Community College Southwest Barbara Shoplock, Florida State University Alan Stam, Capital University Christopher Swan, University of Maryland Alessandro Tagliabue, Stanford University Charles Trick, University of Western Ontario Peter Turchin, University of Connecticut Joe von Fischer, Colorado State University Mitch Wagener, Western Connecticut State University David Webster, University of North Carolina at Wilmington Jake Weltzin, University of Tennessee The publication of a modern textbook requires the work of many editors to handle the specialized tasks of development, photography, graphic design, illustration, copy editing, and production, to name only a few. We’d like to thank acquisitions editor Star MacKenzie for her editorial guidance. Her ideas and efforts have help to shape this edition. We’d also like to thank the rest of the editorial team—Leata Holloway, Project Editor; Lee Ann Doctor, Media Producer; and Frances Sink, Assistant Editor. We also appreciate the efforts of Production Project Manager Shannon Tozier and Debbie Meyer at Integra-Chicago, for keeping the book on schedule. Finally, we are indebted to Brian Morris at Scientific Illustrators, for all his efforts on the art program. Through it all our families, especially our spouses Nancy and Alice, had to endure the throes of book production. Their love, understanding, and support provide the balanced environment that makes our work possible. Thomas M. Smith Robert Leo Smith xx CHAPTER The Nature of Ecology 1.1 Ecology Is the Study of the Relationship between Organisms and Their Environment 1.2 Organisms Interact with the Environment in the Context of the Ecosystem 1.3 Ecological Systems Form a Hierarchy 1.4 Ecologists Study Pattern and Process at Many Levels 1.5 Ecologists Investigate Nature Using the Scientific Method 1.6 Models Provide a Basis for Predictions 1.7 Uncertainty Is an Inherent Feature of Science 1.8 Ecology Has Strong Ties to Other Disciplines 1.9 The Individual Is the Basic Unit of Ecology 1 As part of an ongoing research project, wildlife biologists in Alaska fit a Barren-ground Caribou (Rangifer tarandus groenlandicus) with a radio collar to track the animal and map its patterns of movement and habitat use. 1 2 CHAPTER 1 • THE NATURE OF ECOLOGY T he color photograph of Earthrise, taken by Apollo 8 astronaut William A. Anders on December 24, 1968, is a powerful and eloquent image (Figure 1.1). One leading environmentalist has rightfully described it as “the most influential environmental photograph ever taken.” Inspired by the photograph, economist Kenneth E. Boulding summed up the finite nature of our planet as viewed in the context of the vast expanse of space in his metaphor “spaceship Earth.” What had been perceived throughout human history as a limitless frontier had suddenly become a tiny sphere: limited in its resources, crowded by an ever-expanding human population, and threatened by our use of the atmosphere and the oceans as repositories for our consumptive wastes. A little more than a year later, on April 22, 1970, as many as 20 million Americans participated in environmental rallies, demonstrations, and other activities as part of the first Earth Day. The New York Times commented on the astonishing rise in environmental awareness, stating that “Rising concern about the environmental crisis is sweeping the nation’s campuses with an intensity that may be on its way to eclipsing student discontent over the war in Vietnam.” At the core of this social movement was a belief in the need to redefine our relationship with nature, and the particular field of study called upon to provide the road map for this new course of action was ecology. 1.1 Ecology Is the Study of the Relationship between Organisms and Their Environment With the growing environmental movement of the late 1960s and early 1970s, ecology—until then familiar only to a relatively small number of academic and applied biologists—was suddenly thrust into the limelight (see Ecological Issues: Ecology Has Complex Roots). Hailed as a framework for understanding the relationship of humans to their environment, ecology became a household word that appeared in newspapers, magazines, and books—although the term was often misused. Even now, people confuse it with terms such as environment and environmentalism. Ecology is neither. Environmentalism is activism with a stated aim of protecting the natural environment, particularly from the Figure 1.1 Photograph of Earthrise taken by Apollo 8 astronaut William A. Anders on December 24, 1968. negative impacts of human activities. This activism often takes the form of public education programs, advocacy, legislation, and treaties. So what is ecology? Ecology is a science. According to one accepted definition, ecology is the scientific study of the relationships between organisms and their environment. That definition is satisfactory so long as one considers relationships and environment in their fullest meanings. Environment includes the physical and chemical conditions as well as the biological or living components of an organism’s surroundings. Relationships include interactions with the physical world as well as with members of the same and other species. The term ecology comes from the Greek words oikos, meaning “the family household,” and logy, meaning “the study of.” It has the same root word as economics, meaning “management of the household.” In fact, the German zoologist Ernst Haeckel, who originally coined the term ecology in 1866, made explicit reference to this link when he wrote: By ecology we mean the body of knowledge concerning the economy of nature—the investigation of the total relations of the animal both to its inorganic and to its organic; including above all, its friendly and inimical relations with those animals and plants with which it comes directly or indirectly into contact—in a word, ecology is the study of all those complex interrelationships referred to by Darwin as the conditions of the struggle for existence. Haeckel’s emphasis on the relation of ecology to the new and revolutionary ideas put forth in Charles Darwin’s The Origin of Species (1859) is important. Darwin’s theory of natural selection (Haeckel called it “the struggle for existence”) is a cornerstone of the science of ecology. It is a mechanism allowing the study of ecology to go beyond descriptions of natural history and examine the processes that control the distribution and abundance of organisms. 1.2 Organisms Interact with the Environment in the Context of the Ecosystem Organisms interact with their environment at many levels. The physical and chemical conditions surrounding an organism— such as ambient temperature, moisture, concentrations of oxygen and carbon dioxide, and light intensity—all influence basic physiological processes crucial to survival and growth. An organism must acquire essential resources from the surrounding environment and in doing so must protect itself from becoming food for other organisms. It must recognize friend from foe, differentiating between potential mates and possible predators. All of this effort is an attempt to succeed at the ultimate goal of all living organisms: to pass their genes on to successive generations. The environment in which each organism carries out this “struggle for existence” is a place—a physical location in time and space. It can be as large and stable as an ocean or as small and transient as a puddle on the soil surface after a spring rain. CHAPTER 1 • THE NATURE OF ECOLOGY ECOLOG IC AL IS S U ES T Ecology Has Complex Roots he genealogy of most sciences is direct. Tracing the roots of chemistry and physics is relatively easy. The science of ecology is different: its roots are complex. You can argue that ecology goes back to the ancient Greek scholar Theophrastus, a friend of Aristotle, who wrote about the relations between organisms and the environment. On the other hand, ecology as we know it today has vital roots in plant geography and natural history. In the 1800s, botanists began exploring and mapping the world’s vegetation. One of the early plant geographers was Carl Ludwig Willdenow (1765–1812). He pointed out that similar climates supported vegetation similar in form, even though the species were different. Another was Friedrich Heinrich Alexander von Humboldt (1769–1859), for whom the Humboldt Current is named. He spent five years exploring Latin America, including the Orinoco and Amazon rivers. Humboldt correlated vegetation with environmental characteristics and coined the term plant association. Among a second generation of plant geographers was Johannes Warming (1841–1924) at the University of Copenhagen, who studied the tropical vegetation of Brazil. He wrote the first text on plant ecology, Plantesamfund. In this book Warming integrated plant morphology, physiology, taxonomy, and biogeography into a coherent whole. This book had a tremendous influence on the development of ecology. Early plant ecologists were concerned mostly with terrestrial vegetation. Another group of European biologists was interested in the relationship between aquatic plants and animals and their environment. They advanced the ideas of organic nutrient cycling and feeding levels, using the terms producers and consumers. Their work influenced a young limnologist at the University of Minnesota, R. A. Lindeman. He traced “energy-available” relationships within a lake community. His 1942 paper, “The Trophic-Dynamic Aspects of Ecology,” marked the beginning of ecosystem ecology, the study of whole living systems. Lindeman’s theory stimulated further pioneering work in the area of energy flow and nutrient cycling by G. E. Hutchinson of Yale University and E. P. and H. T. Odum of the University of Georgia. Their work became a foundation of ecosystem ecology. The use of radioactive tracers, a product of the atomic age, to measure the movements of energy and nutrients through ecosystems and the use of computers to analyze large amounts of data stimulated the development of systems ecology, the application of general system theory and methods to ecology. Activities in other areas of natural history also assumed important roles. One was the voyage of Charles Darwin (1809–1882) on the Beagle. Working for years on notes and collections from this trip, Darwin compared similarities and dissimilarities among organisms within and among continents. He attributed differences to geological barriers. He noted how successive groups of plants and animals, distinct yet obviously related, replaced one another. Developing his theory of evolution and the origin of species, Darwin came across the writings of Thomas Malthus (1766–1834). An economist, Malthus advanced the principle that populations grow in a geometric fashion, doubling at regular intervals until they outstrip the food supply. Ultimately, a “strong, constantly operating force such as sickness and premature death” would restrain the population. From this concept Darwin developed the idea of “the survival of the fittest” as a mechanism of natural selection and evolution. Meanwhile, unknown to Darwin, an Austrian monk, Gregor Mendel (1822–1884), was studying the transmission of characteristics from one generation of pea plants to another in his garden. Mendel’s work on inheritance and Darwin’s work on natural selection provided the foundation for the study of evolution and adaptation, the field of population genetics. Interest in Malthusian theory stimulated the study of population in two directions. One, population ecology, is concerned with population growth (including birthrates and death rates), regulation and intraspecific and interspecific competition, mutualism, and predation. The other, a combination of population genetics and population ecology is evolutionary ecology that deals with the role of natural selection in physical and behavioural adaptations and speciation. Focusing on adaptations, physiological ecology is concerned with the responses of individual organisms to temperature, moisture, light, and other environmental conditions. Closely associated with population and evolutionary ecology is community ecology, which deals with the physical and biological structure of communities and community development. Associated with community ecology is landscape ecology, the study of causes behind landscape patterns and the ecological consequences of spatial patterns on the landscape. Natural history observations led to studies of animal reactions to their living and nonliving environment. It began with 19th-century behavioral studies including those of ants by William Wheeler and of South American monkeys by Charles Carpenter. Later, the pioneering studies of Konrad Lorenz and Niko Tinbergen on the role of imprinting and instinct in the social life of animals, particularly birds and fish, gave rise to ethology. It spawned an offshoot behavioral ecology, exemplified early by L. E. Howard’s study on territoriality in birds. Behavioral ecology is concerned with intraspecific and interspecific relationships such as mating, foraging, and defense and how behavior is influenced by natural selection, all tying into evolutionary ecology. Other observations led to investigations of chemical substances in the natural world. Scientists began to explore the use and nature of chemicals in animal recognition, trail-making, and courtship, and in plant and animal defense. Such studies make up the specialized field of chemical ecology. Ecology has so many roots that it probably will always remain many-faceted—as the ecological historian Robert McIntosh calls it, “a polymorphic discipline.” Insights from these many specialized areas of ecology will continue to enrich the science as it moves forward into the 21st century. 3 sample content of Elements of Ecology (7th Edition) On Balance for free download online Die Maahks (Perry Rhodan Silberbände, Band 23; Die Meister der Insel, Band 3) book download online Tuf Voyaging download online Invincible, The Games of Shusaku (Game Collections) How the Chicago School Overshot the Mark: The Effect of Conservative Economic Analysis on U.S. Antitrust pdf, azw (kindle), epub, doc, mobi http://creativebeard.ru/freebooks/On-Balance.pdf http://deltaphenomics.nl/?library/Die-Maahks--Perry-Rhodan-Silberb--nde--Band-23--DieMeister-der-Insel--Band-3-.pdf http://www.uverp.it/library/Genealogy-Online-For-Dummies--7th-Edition-.pdf http://qolorea.com/library/Time-Varying-Vector-Fields-and-Their-Flows.pdf http://hasanetmekci.com/ebooks/How-the-Chicago-School-Overshot-the-Mark--The-Effect-ofConservative-Economic-Analysis-on-U-S--Antitrust.pdf Powered by TCPDF (www.tcpdf.org)