Introduction to Ecology Section 1 Introduction to...

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Introduction to EcologyChapter 18

Table of Contents

Section 1 Introduction to Ecology

Section 2 Ecology of Organisms

Section 3 Energy Transfer

Section 4 Ecosystem Recycling




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.




Chapter 18

Interdependence: A Key Theme in Ecology

• Organisms and Their Environments

– Species interact with both other species and their

nonliving environment.




Chapter 18

Ecological Models

• Ecological models help to explain the environment.



Chapter 18

Making an Ecosystem Model





Chapter 18

Levels of Organization

• Ecologists recognize a hierarchy of organization in

the environment: biosphere, ecosystem, community,

population, and organism.



Chapter 18

Levels of Organization





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.




Chapter 18


• 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.



Chapter 18

Ecosystem





Chapter 18


• 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.



Chapter 18

Community





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.




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.




Chapter 18

Organisms in a Changing Environment

• Acclimation

– Some organisms can adjust their tolerance to

abiotic factors through the process of acclimation.




Chapter 18

Organisms in a Changing Environment,

continued

• Escape from Unsuitable Conditions

– Some species survive unfavorable environmental

conditions by becoming dormant or by migrating.




Chapter 18

The Niche

• A niche is a way of life, or a role in an ecosystem.



Chapter 18

Earthworm Niche

Section 2 Ecology Of Organisms




Chapter 18

Objectives

• 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.




Chapter 18

Producers

• Most producers are photosynthetic and make

carbohydrates by using energy from the sun.




Chapter 18

Consumers

• Consumers obtain energy by eating other organisms

and include herbivores, omnivores, carnivores,

detritivores, and decomposers.




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.



Chapter 18

Food Chains and Food Webs




Chapter 18

Food Chain in an Antarctic Ecosystem




Chapter 18

Food Web

in an

Antarctic

Ecosystem





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.



Chapter 18

Energy Transfer Through Trophic Levels




Chapter 18

Energy Pyramid





Chapter 18

Objectives

• 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.




Chapter 18

The Water Cycle

• Key processes in the water cycle are evaporation,

transpiration, and precipitation.



Chapter 18

Water Cycle





Chapter 18

The Carbon Cycle

• Photosynthesis and cellular respiration are the two

main steps in the carbon cycle.



Chapter 18

Carbon Cycle





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.



Chapter 18

Nitrogen Cycle


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