Ecology

1. The Web of Life
Deformity and Decline in Amphibian Populations: A Case Study
Introduction
Concept 1.1. Events in the natural world are interconnected
Connections in Nature
Concept 1.2. Ecology is the scientific study of interactions between organisms and their environment.
What Is Ecology?
Concept 1.3. Ecologists evaluate competing hypotheses about natural systems with observations, experiments, and models.
Answering Ecological Questions
Climate Change Connection: Approaches Used To Study Global Warming
Ecological Toolkit 1.1. Designing Ecological Experiments
Analyzing Data 1.1. Are Introduced Predators a Cause of Amphibian Decline?
A Case Study Revisited: Deformity and Decline in Amphibian Populations
Connections in Nature: Mission Impossible?

UNIT 1. ORGANISMS AND THEIR ENVIRONMENT

2. The Physical Environment
Climate Variation and Salmon Abundance: A Case Study
Introduction
Concept 2.1. Climate is the most fundamental component of the physical environment.
Climate
Concept 2.2. Winds and ocean currents result from differences in solar radiation across Earth's surface.
Atmospheric and Oceanic Circulation
Concept 2.3. Large-scale atmospheric and oceanic circulation patterns establish global patterns of temperature and precipitation.
Global Climate Patterns
Concept 2.4. Regional climates reflect the influence of oceans and continents, mountains, and vegetation.
Regional Climate Influences
Analyzing data 2.1. How Do Changes in Vegetation Cover Influence Climate?
Concept 2.5. Seasonal and long-term climate variation are associated with changes in Earth's position relative to the sun.
Climate Variation over Time
Concept 2.6. Salinity, acidity, and oxygen concentrations are major determinants of the chemical environment.
The Chemical Environment
A Case Study Revisited: Climate Variation and Salmon Abundance
Connections in Nature: Climate Variation and Ecology

3. The Biosphere
The American Serengeti-Twelve Centuries of Change in the Great Plains: A Case Study
Introduction
Concept 3.1. Terrestrial biomes are characterized by the growth forms of the dominant vegetation.
Terrestrial Biomes
Ecological Toolkit 3.1. Climate Diagrams
Climate Change Connection: Tropical Forests and Greenhouse Gases
Analyzing Data 3.1. How Will Climate Change Affect the Grasslands Biome?
Concept 3.2. Biological zones in freshwater ecosystems are associated with the velocity, depth, temperature, clarity, and chemistry of the water.
Freshwater Biological Zones
Concept 3.3. Marine biological zones are determined by ocean depth, light availability, and the stability of the bottom substrate.
Marine Biological Zones
A Case Study Revisited:The American Serengeti-Twelve Centuries of Change in the Great Plains
Connections in Nature: Long-Term Ecological Research

4. Coping with Environmental Variation: Temperature and Water
Frozen Frogs: A Case Study
Introduction
Concept 4.1. Each species has a range of environmental tolerances that determines its potential geographic distribution.
Responses to Environmental Variation
Concept 4.2. The temperature of an organism is determined by exchanges of energy with the external environment.
Variation in Temperature
Analyzing Data 4.1. How Does Fur Thickness Influence Metabolic Activity in Endotherms?
Concept 4.3. The water balance of an organism is determined by exchanges of water and solutes with the external environment.
Variation in Water Availability
A Case Study Revisited: Frozen Frogs
Connections in Nature: Desiccation Tolerance, Body Size, and Rarity

5. Coping with Environmental Variation: Energy
Toolmaking Crows: A Case Study
Introduction
Concept 5.1. Organisms obtain energy from sunlight, from inorganic chemical compounds, or through the consumption of organic compounds.
Sources of Energy
Concept 5.2. Radiant and chemical energy captured by autotrophs is converted into stored energy in carbon-carbon bonds.
Autotrophy
Analyzing Data 5.1. How Does Acclimatization Affect Plant Energy Balance?
Concept 5.3. Environmental constraints have resulted in the evolution of biochemical pathways that improve the efficiency of photosynthesis.
Photosynthetic Pathways
Concept 5.4. Heterotrophs have adaptations for acquiring and assimilating energy efficiently from a variety of organic sources.
Heterotrophy
Ecological Toolkit 5.1. Stable Isotopes
A Case Study Revisited: Toolmaking Crows
Connections in Nature: Tool Use: Adaptation or Learned Behavior?

UNIT 2. EVOLUTIONARY ECOLOGY

6. Evolution and Ecology
Trophy Hunting and Inadvertent Evolution: A Case Study
Introduction
Concept 6.1. Evolution can be viewed as genetic change over time or as a process of descent with modification.
What Is Evolution?
Concept 6.2. Natural selection, genetic drift, and gene flow can cause allele frequencies in a population to change over time.
Mechanisms of Evolution
Concept 6.3. Natural selection is the only evolutionary mechanism that consistently causes adaptive evolution.
Adaptive Evolution
Climate Change Connection: Evolutionary Responses to Climate Change
Concept 6.4. Long-term patterns of evolution are shaped by large-scale processes such as speciation, mass extinction, and adaptive radiation.
The Evolutionary History of Life
Concept 6.5. Ecological interactions and evolution exert a profound influence on one another.
Joint Effects of Ecology and Evolution
A Case Study Revisited: Trophy Hunting and Inadvertent Evolution
Connections in Nature: The Human Impact on Evolution
Analyzing Data 6.1: Does Predation by Birds Cause Evolution in Moth Populations?

7. Life History
Nemo Grows Up: A Case Study
Introduction
Concept 7.1. Life history patterns vary within and among species.
Life History Diversity
Climate Change Connection: Climate Change and the Timing of Seasonal Activities
Concept 7.2. Reproductive patterns can be classified along several continua.
Life History Continua
Concept 7.3. There are trade-offs between life history traits.
Trade-Offs
Concept 7.4. Organisms face different selection pressures at different life cycle stages.
Life Cycle Evolution
Analyzing Data 7.1. Is There a Trade-Off between Current and Delayed Reproduction in the Collared Flycatcher??
A Case Study Revisited: Nemo Grows Up
Connections in Nature: Territoriality, Competition, and Life History

8. Behavioral Ecology
Baby Killers: A Case Study
Introduction
Concept 8.1. An evolutionary approach to the study of behavior leads to testable predictions.
An Evolutionary Approach to Behavior
Concept 8.2. Animals make behavioral choices that enhance their energy gain and reduce their risk of becoming prey.
Foraging Behavior
Concept 8.3. Mating behaviors reflect the costs and benefits of parental investment and mate defense.
Mating Behavior
Concept 8.4. There are advantages and disadvantages to living in groups.
Living in Groups
Analyzing data 8.1. Does the Dilution Effect Protect Individual Ocean Skaters from Fish Predators?
A Case Study Revisited: Baby Killers
Connections in Nature: Behavioral Responses to Predators Have Broad Ecological Effects

UNIT 3. POPULATIONS

9. Population Distribution and Abundance
From Kelp Forest to Urchin Barren: A Case Study
Introduction
Concept 9.1. Populations are dynamic entities that vary in size over time and space.
Populations
Concept 9.2. The distributions and abundances of organisms are limited by habitat suitability, historical factors, and dispersal.
Distribution and Abundance
Analyzing Data 9.1. Have Introduced Grasses Altered the Occurrence of Fires in Hawaiian Dry Forests?
Concept 9.3. Many species have a patchy distribution of populations across their geographic range.
Geographic Range
Concept 9.4. The dispersion of individuals within a population depends on the location of essential resources, competition, dispersal, and behavioral interactions.
Dispersion within Populations
Concept 9.5. Population abundances and distributions can be estimated with area-based counts, distance methods, mark-recapture studies, and niche models.
Estimating Abundances and Distributions
Ecological Toolkit 9.1. Estimating Abundance
A Case Study Revisited: From Kelp Forest to Urchin Barren
Connections in Nature: From Urchins to Ecosystems
Climate Change Connection: Effects of Climate Change on the Geographic Distributions of Species

10. Population Growth and Regulation
Human Population Growth: A Case Study
Introduction
Concept 10.1. Life tables show how survival and reproductive rates vary with age, size, or life cycle stage.
Life Tables
Concept 10.2. Life table data can be used to project the future age structure, size, and growth rate of a population.
Age Structure
Climate Change Connection: Effects of Climate Change on Tree Mortality Rates
Ecological Toolkit 10.1. Estimating Population Growth Rates in a Threatened Species
Concept 10.3. Populations can grow exponentially when conditions are favorable, but exponential growth cannot continue indefinitely.
Exponential Growth
Analyzing Data 10.1. How Has the Growth of the Human Population Changed over Time?
Concept 10.4. Population size can be determined by density-dependent and density-independent factors.
Effects of Density
Concept 10.5. The logistic equation incorporates limits to growth and shows how a population may stabilize at a maximum size, the carrying capacity.
Logistic Growth
A Case Study Revisited: Human Population Growth
Connections in Nature: Your Ecological Footprint

11. Population Dynamics
A Sea in Trouble: A Case Study
Introduction
Concept 11.1. Population growth patterns include exponential growth, logistic growth, fluctuations, and regular cycles.
Patterns of Population Growth
Climate Change Connection: Collapsing Population Cycles and Climate Change
Concept 11.2. Delayed density dependence can cause populations to fluctuate in size.
Delayed Density Dependence
Concept 11.3. The risk of extinction increases greatly in small populations.
Population Extinction
Analyzing Data 11.1. How Does Variation in l Affect Population Growth?
Concept 11.4. In metapopulations, sets of spatially isolated populations are linked by dispersal.
Metapopulations
A Case Study Revisited: A Sea in Trouble
Connections in Nature: From Bottom to Top, and Back Again

UNIT 4. SPECIES INTERACTIONS

12. Predation
Snowshoe Hare Cycles: A Case Study
Introduction
Concept 12.1. Most carnivores have broad diets, whereas a majority of herbivores have relatively narrow diets.
Carnivore and Herbivore Dietary Preferences
Concept 12.2. Predation results in a wide range of capture and avoidance mechanisms.
Mechanisms Important to Predation
Concept 12.3. Predator populations can cycle with their prey populations.
Predator-Prey Population Cycles
Analyzing Data 12.1. Do Different Herbivore Species Select for Different Plant Genotypes?
Concept 12.4. Predation can affect prey distribution and abundance, in some cases causing a shift from one community type to another.
Effects of Predation on Communities
A Case Study Revisited: Snowshoe Hare Cycles
Connections in Nature: From Fear to Hormones to Population Dynamics

13. Parasitism
Enslaver Parasites: A Case Study
Introduction
Concept 13.1. Parasites typically feed on only one or a few host species, but host species have multiple parasite species.
Parasite Natural History
Concept 13.2. Hosts have mechanisms for defending themselves against parasites, and parasites have mechanisms for overcoming host defenses.
Defense and Counterdefenses
Analyzing Data 13.1. Will a Defensive Symbiont Increase in Frequency in a Host Population Subjected to Parasitism?
Concept 13.3. Host and parasite populations can evolve together, each in response to selection pressure imposed by the other.
Parasite-Host Coevolution
Concept 13.4. Hosts and parasites can have important effects on each other's population dynamics.
Host-Parasite Population Dynamics
Concept 13.5. Parasites can alter the outcomes of species interactions, thereby causing communities to change.
Parasites Can Change Ecological Communities
Climate Change Connection: Climate Change and Disease Spread
A Case Study Revisited: Enslaver Parasites
Connections in Nature: From Chemicals to Evolution and Ecosystems

14. Competition
Competition in Plants That Eat Animals: A Case Study
Introduction
Concept 14.1. Competition can be direct or indirect, vary in its intensity, and occur between similar or dissimilar species.
General Features of Competition
Concept 14.2. Competing species are more likely to coexist when they use resources in different ways.
Competitive Coexistence
Concept 14.3. Competitive interactions can be modeled using the logistic equation.
The Lotka-Volterra Competition Model
Analyzing Data 14.1. Will Competition with a Native Mosquito Species Prevent the Spread of an Introduced Mosquito?
Concept 14.4. The outcome of competition can be altered by the physical environment, disturbance, and predation.
Altering the Outcome of Competition
A Case Study Revisited: Competition in Plants That Eat Animals
Connections in Nature: The Paradox of Diversity

15. Mutualism and Commensalism
The First Farmers: A Case Study
Introduction
Concept 15.1. In positive interactions, no species is harmed and the benefits are greater than the costs for at least one species.
Positive Interactions
Concept 15.2. Each partner in a mutualistic interaction acts in ways that serve its own ecological and evolutionary interests.
Characteristics of Mutualism
Analyzing Data 15.1. Does a Mycorrhizal Fungus Transfer More Phosphorus to Plant Roots That Provide More Carbohydrates?
Concept 15.3. Positive interactions affect the abundances and distributions of populations as well as the structure of ecological communities.
Ecological Consequences of Positive Interactions
A Case Study Revisited: The First Farmers
Connections in Nature: From Mandibles to Nutrient Cycling

UNIT 5. COMMUNITIES

16. The Nature of Communities
"Killer Algae!": A Case Study
Introduction
Concept 16.1. Communities are groups of interacting species that occur together at the same place and time.
What Are Communities?
Concept 16.2. Species diversity and species composition are important descriptors of community structure.
Community Structure
Analyzing Data 16.1. What Are the Effects of Invasive Species on Species Diversity?
Concept 16.3. Communities can be characterized by complex networks of direct and indirect interactions that vary in strength and direction.
Interactions of Multiple Species
Ecological Toolkit 16.1. Measurements of Interaction Strength
Climate Change Connection: Context Dependence of Ocean Acidification
A Case Study Revisited: "Killer Algae!"
Connections in Nature: Stopping Invasions Requires Commitment

17. Change in Communities
A Natural Experiment of Mountainous Proportions: A Case Study
Introduction
Concept 17.1. Agents of change act on communities across all temporal and spatial scales.
Agents of Change
Concept 17.2. Succession is the process of change in species composition over time as a result of abiotic and biotic agents of change.
The Basics of Succession
Concept 17.3. Experimental work on succession shows its mechanisms to be diverse and context-dependent.
Mechanisms of Succession
Analyzing Data 17.1. What Kinds of Species Interactions Drive Succession in Mountain Forests?
Concept 17.4. Communities can follow different successional paths and display alternative states.
Alternative Stable States
A Case Study Revisited: A Natural Experiment of Mountainous Proportions
Connections in Nature: Primary Succession and Mutualism

18. Biogeography
The Largest Ecological Experiment on Earth: A Case Study
Introduction
Concept 18.1. Patterns of species diversity and distribution vary at global, regional, and local spatial scales.
Biogeography and Spatial Scale
Concept 18.2. Global patterns of species diversity and composition are influenced by geographic area and isolation, evolutionary history, and global climate.
Global Biogeography
Climate Change Connection: Latitudinal Gradients in Diversity under Climate Change
Concept 18.3. Regional differences in species diversity are influenced by area and distance, which determine the balance between immigration and extinction rates.
Regional Biogeography
Ecological Toolkit 18.1. Species-Area Curves
Analyzing data 18.1. Do Species Invasions Influence Species-Area Curves?
A Case Study Revisited: The Largest Ecological Experiment on Earth
Connections in Nature: Tropical Rainforest Diversity Benefits Humans

19. Species Diversity in Communities
Can Species Diversity Suppress Human Diseases? A Case Study
Introduction
Concept 19.1. Species diversity differs among communities as a consequence of regional species pools, abiotic conditions, and species interactions.
Community Membership
Climate Change Connection: How Are Species Invasions Enhanced by Climate Change?
Concept 19.2. Resource partitioning is theorized to reduce competition and increase species diversity.
Resource Partitioning
Concept 19.3. Processes such as disturbance, stress, predation, and positive interactions can mediate resource availability, thus promoting species diversity.
Resource Mediation and Species Diversity
Analyzing data 19.1. How Do Predation and Dispersal Interact to Influence Species Richness?
Concept 19.4. Many experiments show that species diversity affects community function.
The Consequences of Diversity
A Case Study Revisited: Can Species Diversity Suppress Human Diseases?
Connections in Nature: Managing Pathogens by Managing Biodiversity

UNIT 6. ECOSYSTEMS

20. Production
Life in the Deep Blue Sea, How Can It Be? A Case Study
Introduction
Concept 20.1. Energy in ecosystems originates with primary production by autotrophs.
Primary Production
Ecological Toolkit 20.1. Remote Sensing
Analyzing data 20.1. Does Deforestation Influence Atmospheric CO2 Concentrations?
Concept 20.2. Net primary production is constrained by both physical and biotic environmental factors.
Environmental Controls on NPP
Concept 20.3. Global patterns of net primary production reflect climate constraints and biome types.
Global Patterns of NPP
Concept 20.4. Secondary production is generated through the consumption of organic matter by heterotrophs.
Secondary Production
A Case Study Revisited: Life in the Deep Blue Sea, How Can It Be?
Connections in Nature: Energy-Driven Succession and Evolution in Hydrothermal Vent Communities

21. Energy Flow and Food Webs
Toxins in Remote Places: A Case Study
Introduction
Concept 21.1.Trophic levels describe the feeding positions of groups of organisms in ecosystems.
Feeding Relationships
Concept 21.2. The amount of energy transferred from one trophic level to the next depends on food quality and on consumer abundance and physiology.
Energy Flow between Trophic Levels
Concept 21.3. Changes in the abundances of organisms at one trophic level can influence energy flow at multiple trophic levels.
Trophic Cascades
Analyzing data 21.1. Does the Identity of Organisms Influence Energy Flow between Trophic Levels?
Concept 21.4. Food webs are conceptual models of the trophic interactions of organisms in an ecosystem.
Food Webs
A Case Study Revisited: Toxins in Remote Places
Connections in Nature: Biological Transport of Pollutants

22. Nutrient Supply and Cycling
A Fragile Crust: A Case Study
Introduction
Concept 22.1. Nutrients enter ecosystems through the chemical breakdown of minerals in rocks or through fixation of atmospheric gases.
Nutrient Requirements and Sources
Concept 22.2. Chemical and biological transformations in ecosystems alter the chemical form and supply of nutrients.
Nutrient Transformations
Analyzing data 22.1. Does Lignin Always Inhibit Decomposition?
Concept 22.3. Nutrients cycle repeatedly through the components of ecosystems.
Nutrient Cycles and Losses
Ecological Toolkit 22.1. Instrumenting Catchments
Concept 22.4. Freshwater and marine nutrient cycles occur in a moving medium and are linked to terrestrial ecosystems.
Nutrients in Aquatic Ecosystems
A Case Study Revisited: A Fragile Crust
Connections in Nature: Nutrients, Disturbance, and Invasive Species

UNIT 7. APPLIED AND LARGE-SCALE ECOLOGY

23. Conservation Biology
Can Birds and Bombs Coexist? A Case Study
Introduction
Concept 23.1. Conservation biology is an integrative discipline that applies the principles of ecology to the protection of biodiversity.
Conservation Biology
Concept 23.2. Biodiversity is declining globally.
Declining Biodiversity
Concept 23.3. Primary threats to biodiversity include habitat loss, invasive species, overexploitation, pollution, disease, and climate change.
Threats to Biodiversity
Analyzing Data 23.1. Do Nitric Oxide Emissions Differ Statistically between Plots with and without Kudzu?
Climate Change Connection: Impacts on Biodiversity
Concept 23.4. Conservation biologists use many tools and work at multiple scales to manage declining populations.
Approaches to Conservation
Ecological Toolkit 23.1. Forensics in Conservation Biology
Concept 23.5. Prioritizing species helps maximize the biodiversity that can be protected with limited resources.
Ranking Species for Protection
A Case Study Revisited: Can Birds and Bombs Coexist?
Connections in Nature: Some Burning Questions

24. Landscape Ecology and Ecosystem Management
Wolves in the Yellowstone Landscape: A Case Study
Introduction
Ecological Toolkit 24.1. Geographic Information Systems (GIS)
Concept 24.1. Landscape ecology examines spatial patterns and their relationship to ecological processes.
Landscape Ecology
Concept 24.2. Habitat loss and fragmentation decrease habitat area, isolate populations, and alter conditions at habitat edges.
Habitat Loss and Fragmentation
Analyzing data 24.1. How Far Do Edge Effects Penetrate into Forest Fragments?
Concept 24.3. Biodiversity can best be sustained by large reserves connected across the landscape and buffered from areas of intense human use.
Designing Nature Reserves
Concept 24.4. Ecosystem management is a collaborative process with the maintenance of long-term ecological integrity as its core value.
Ecosystem Management
A Case Study Revisited: Wolves in the Yellowstone Landscape
Connections in Nature: Future Changes in the Yellowstone Landscape

25. Global Ecology
Dust Storms of Epic Proportions: A Case Study
Introduction
Concept 25.1. Elements move among geologic, atmospheric, oceanic, and biological pools at a global scale.
Global Biogeochemical Cycles
Analyzing Data 25.1. How Much Will Ocean pH Drop in the Twenty-First Century?
Concept 25.2. Earth is warming because of anthropogenic emissions of greenhouse gases.
Global Climate Change
Concept 25.3. Anthropogenic emissions of sulfur and nitrogen cause acid deposition, alter soil chemistry, and affect the health of ecosystems.
Acid and Nitrogen Deposition
Concept 25.4. Losses of ozone in the stratosphere and increases in ozone in the troposphere both pose risks to organisms.
Atmospheric Ozone
A Case Study Revisited: Dust Storms of Epic Proportions
Connections in Nature: Dust as a Vector of Ecological Impacts

Appendix: Some Metric Measurements Used in Ecology
Answers
Glossary
Illustration and Photo Credits
Literature Cited
Index