1. Chapter 18 Table of Contents Section 1 Introduction to Ecology
Section 2 Ecology of Organisms
Section 3 Energy Transfer
Section 4 Ecosystem Recycling

2. Chapter 18 Objectives Identify a key theme in ecology.
Section 1 Introduction to Ecology
Chapter 18
Objectives
Identify a key theme in ecology.
Describe an example showing the effects of interdependence upon organisms in their environment.
Identify the importance of models to ecology.
State the five different levels of organization at which ecology can be studied.

3. Interdependence: A Key Theme in Ecology
Section 1 Introduction to Ecology
Chapter 18
Interdependence: A Key Theme in Ecology
Organisms and Their Environments
Species interact with both other species and their nonliving environment.
Interdependence is a theme in ecology—one change can affect all species in an ecosystem.

4. Chapter 18 Ecological Models
Section 1 Introduction to Ecology
Chapter 18
Ecological Models
Ecological models help to explain the environment.

5. Making an Ecosystem Model
Section 1 Introduction to Ecology
Chapter 18
Making an Ecosystem Model

6. Levels of Organization
Section 1 Introduction to Ecology
Chapter 18
Levels of Organization
Ecologists recognize a hierarchy of organization in the environment: biosphere, ecosystem, community, population, and organism.

7. Levels of Organization
Section 1 Introduction to Ecology
Chapter 18
Levels of Organization

8. Levels of Organization, continued
Section 1 Introduction to Ecology
Chapter 18
Levels of Organization, continued
The Biosphere
The broadest, most inclusive level of organization is the biosphere, the volume of Earth and its atmosphere that supports life.

9. Levels of Organization, continued
Section 1 Introduction to Ecology
Chapter 18
Levels of Organization, continued
Ecosystems
The biosphere is composed of smaller units called ecosystems.
An ecosystem includes all of the organisms and the nonliving environment found in a particular place.

10. Levels of Organization, continued
Section 1 Introduction to Ecology
Chapter 18
Levels of Organization, continued
Communities, Populations, and Organisms
A community is all the interacting organisms living in an area.
Below the community level of organization is the population level, where the focus is on the individual organisms of a single species.

11. Section 2 Ecology of Organisms
Chapter 18
Objectives
Compare abiotic factors with biotic factors, and list two examples of each.
Describe two mechanisms that allow organisms to survive in a changing environment.
Explain the concept of the niche.

12. Chapter 18 Ecosystem Components Biotic and Abiotic Factors
Section 2 Ecology of Organisms
Chapter 18
Ecosystem Components
Biotic and Abiotic Factors
Both biotic, or living, factors and abiotic, or nonliving, factors influence organisms. Examples of abiotic factors are climate, sunlight, and pH.

13. Comparing Biotic and Abiotic Factors
Section 2 Ecology of Organisms
Chapter 18
Comparing Biotic and Abiotic Factors
Click below to watch the Visual Concept.
Visual Concept

14. Organisms in a Changing Environment
Section 2 Ecology of Organisms
Chapter 18
Organisms in a Changing Environment
Acclimation
Some organisms can adjust their tolerance to abiotic factors through the process of acclimation.

15. Organisms in a Changing Environment, continued
Section 2 Ecology of Organisms
Chapter 18
Organisms in a Changing Environment, continued
Control of Internal Conditions
Conformers are organisms that do not regulate their internal conditions; they change as their external environment changes.
Regulators use energy to control some of their internal conditions.

16. Organisms in a Changing Environment, continued
Section 2 Ecology of Organisms
Chapter 18
Organisms in a Changing Environment, continued
Escape from Unsuitable Conditions
Some species survive unfavorable environmental conditions by becoming dormant or by migrating.

17. Section 2 Ecology of Organisms
Chapter 18
The Niche
A niche is a way of life, or a role in an ecosystem.

18. Chapter 18 Niche Section 2 Ecology of Organisms
Click below to watch the Visual Concept.
Visual Concept

19. Chapter 18 Objectives Section 3 Energy Transfer
Summarize the role of producers in an ecosystem.
Identify several kinds of consumers in an ecosystem.
Explain the important role of decomposers in an ecosystem.
Compare the concept of a food chain with that of a food web.
Explain why ecosystems usually contain only a few trophic levels.

20. Section 3 Energy Transfer
Chapter 18
Producers
Most producers are photosynthetic and make carbohydrates by using energy from the sun.

21. Chapter 18 Producers, continued Measuring Productivity
Section 3 Energy Transfer
Chapter 18
Producers, continued
Measuring Productivity
Gross primary productivity is the rate at which producers in an ecosystem capture the energy of sunlight by producing organic compounds.
The rate at which biomass accumulates is called net primary productivity.

22. Section 3 Energy Transfer
Chapter 18
Consumers
Consumers obtain energy by eating other organisms and include herbivores, omnivores, carnivores, detritivores, and decomposers.

23. Comparing Consumers and Producers
Section 3 Energy Transfer
Chapter 18
Comparing Consumers and Producers
Click below to watch the Visual Concept.
Visual Concept

24. Chapter 18 Energy Flow Food Chains and Food Webs
Section 3 Energy Transfer
Chapter 18
Energy Flow
Food Chains and Food Webs
A single pathway of energy transfer is a food chain.
A network showing all paths of energy transfer is a food web.

25. Food Chain in an Antarctic Ecosystem
Section 3 Energy Transfer
Chapter 18
Food Chain in an Antarctic Ecosystem

26. Food Web in an Antarctic Ecosystem
Section 3 Energy Transfer
Chapter 18
Food Web in an Antarctic Ecosystem

27. Chapter 18 Energy Flow, continued Energy Transfer
Section 3 Energy Transfer
Chapter 18
Energy Flow, continued
Energy Transfer
Ecosystems contain only a few trophic levels because there is a low rate of energy transfer between each level.

28. Energy Transfer Through Trophic Levels
Section 3 Energy Transfer
Chapter 18
Energy Transfer Through Trophic Levels

29. Chapter 18 Objectives Section 4 Ecosystem Recycling
List four major biogeochemical cycles.
Summarize three important processes in the water cycle.
Outline the major steps in the carbon cycle.
Describe the role of decomposers in the nitrogen cycle.
Summarize the major steps of the phosphorus cycle.

30. Chapter 18 The Water Cycle
Section 4 Ecosystem Recycling
Chapter 18
The Water Cycle
Key processes in the water cycle are evaporation, transpiration, and precipitation.

31. Section 4 Ecosystem Recycling
Chapter 18
Water Cycle

32. Chapter 18 Water Cycle Section 4 Ecosystem Recycling
Click below to watch the Visual Concept.
Visual Concept

33. Chapter 18 The Carbon Cycle
Section 4 Ecosystem Recycling
Chapter 18
The Carbon Cycle
Photosynthesis and cellular respiration are the two main steps in the carbon cycle.

34. Section 4 Ecosystem Recycling
Chapter 18
Carbon Cycle

35. Chapter 18 Carbon Cycle Section 4 Ecosystem Recycling
Click below to watch the Visual Concept.
Visual Concept

36. Chapter 18 Nitrogen Cycle
Section 4 Ecosystem Recycling
Chapter 18
Nitrogen Cycle
Nitrogen-fixing bacteria are important in the nitrogen cycle because they change nitrogen gas into a usable form of nitrogen for plants.

37. Section 4 Ecosystem Recycling
Chapter 18
Nitrogen Cycle

38. Chapter 18 Nitrogen Cycle Section 4 Ecosystem Recycling
Click below to watch the Visual Concept.
Visual Concept

39. Chapter 18 Phosphorus Cycle
Section 4 Ecosystem Recycling
Chapter 18
Phosphorus Cycle
In the phosphorus cycle, phosphorus moves from phosphate deposited in rock, to the soil, to living organisms, and finally to the ocean.