18 interdependence: a key theme chapter in ecology ... 1 introduction to ecology chapter 18 levels...

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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.



Section 1 Introduction to Ecology

Chapter 18

Levels of Organization in studying an

ecological system

• 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 thin volume of Earth and its

atmosphere that supports life.

– All organisms are found in the biosphere

– Extends from ~ 5-6 miles above earth to the

deepest part of the oceans.




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.

• BIOTIC FACTORS--A pond ecosystem

includes all of the fish, turtles, insects, aquatic

plants, algae and bacteria (all living things)



Chapter 18

Ecosystem


•ABIOTIC FACTORS--A pond

ecosystem also includes all of

the physical and chemical

aspects of the pond that

influence its inhabitants.

ie pH, levels of dissolved

oxygen, carbon dioxide, nitrogen

as well as the amount of

sunlight. Temperature, humidity,

salinity, precipitation




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.

• Size, density, and dispersion are characteristics

of populations



Chapter 18

Community




Logistic

Exponential

Population Growth

Logistic vs Exponential- Logistic limited by

resources

Exponential steady

growth rate



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.




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

The Niche

• A niche is a way of life, or a role (What’s your job?)

in an ecosystem.

– Range of conditions the organism can tolerate

– The resources it uses

– Method of obtaining resources

– Number of offspring

– Time of reproduction

– All interactions with its environment



Chapter 18

Earthworm Niche

Section 2 Ecology Of Organisms



Section 3 Energy Transfer

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

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.




Chapter 18

Consumers

• Consumers obtain energy by eating other organisms

and include herbivores, omnivores, carnivores,

detritivores, and decomposers.



Chapter 18

Comparing Consumers and Producers





Chapter 18

Energy Flow

• When one organism eats another, organic

molecules are metabolized and energy

transferred.

• 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.

– ~10% of energy is transferred to the next trophic level

• Some organisms in one trophic level escape being eaten

• When they die, they are eaten by decomposers, but the

energy does not go to a higher trophic level

• Energy transfer is never 100 % efficient when changing

form

• There are many more organisms in lower trophic levels

because higher levels contain less energy and can not

support as many organisms.

• Trophic level = feeding level in an ecosystem



Chapter 18

Energy Transfer Through Trophic Levels There are about 1000 zebras for every lion. There are many

grasses.




Chapter 18

Energy Pyramid




Section 4 Ecosystem Recycling

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.



http://upload.wikimedia.org/wikipedia/commons/2/28/Ozone_cycle.svg



The ozone layer can be depleted by free radical

catalysts, including nitric oxide (NO), nitrous oxide

(N2O), hydroxyl (OH), atomic chlorine (Cl), and

atomic bromine (Br).

• Since stratospheric ozone is produced by solar UV radiation,

one might expect to find the highest ozone levels over the

tropics and the lowest over polar regions. The same argument

would lead one to expect the highest ozone levels in the

summer and the lowest in the winter. The observed behavior is

very different: most of the ozone is found in the mid-to-high

latitudes of the northern and southern hemispheres, and the

highest levels are found in the spring, not summer, and the

lowest in the autumn, not winter in the northern hemisphere

http://en.wikipedia.org/wiki/Nitric_oxide

http://en.wikipedia.org/wiki/Nitrous_oxide

http://en.wikipedia.org/wiki/Hydroxyl

http://en.wikipedia.org/wiki/Chlorine

http://en.wikipedia.org/wiki/Bromine




Chapter 18

The Water Cycle

• Key processes in the water cycle are evaporation,

transpiration, and precipitation.

• Transpiration is a process similar to evaporation. It

is a part of the water cycle, and it is the loss of water

vapor from parts of plants (similar to sweating),

especially in leaves (stomata) but also in stems.

http://en.wikipedia.org/wiki/Evaporation

http://en.wikipedia.org/wiki/Water_vapor

http://en.wikipedia.org/wiki/Water_vapor

http://en.wikipedia.org/wiki/Plant

http://en.wikipedia.org/wiki/Sweating

http://en.wikipedia.org/wiki/Leaf

http://en.wikipedia.org/wiki/Plant_stem



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




In the last 150 years the concentration of

atmospheric carbon dioxide has risen more than 30%. This has increased the temperature about 1⁰C

since 1900.




Chapter 18

Nitrogen Cycle

• N2 gas makes up 78% of the atmosphere, but

plants cannot use nitrogen unless it is in the form

of nitrate.

• Nitrogen-fixing bacteria are important in the

nitrogen cycle because they change nitrogen gas

into this usable form of nitrogen for plants-nitrogen

fixation.

• The plants supply carbohydrates to the bacteria.



Chapter 18

Nitrogen Cycle





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.



Multiple Choice

1. What are the levels of organization in ecology?

A. cell, tissue, organ, organ system, body

B. organ, organism, population, community

C. organism, population, community, ecosystem,

biosphere

D. population, habitat, ecosystem, biogeochemical

system, planet

Standardized Test Prep Chapter 18



Multiple Choice, continued

1. What are the levels of organization in ecology?

A. cell, tissue, organ, organ system, body

B. organ, organism, population, community

C. organism, population, community, ecosystem,

biosphere

D. population, habitat, ecosystem, biogeochemical

system, planet





2. What makes up an ecosystem?

F. all the habitat types on Earth

G. all parts of Earth where life exists

H. all members of a species in the same area

J. all the living and nonliving factors in an

environment





3. Which of the following are abiotic factors?

A. plants

B. animals

C. sunlight

D. microorganisms





4. How do decomposers benefit an ecosystem?

F. by returning nutrients to the soil

G. by manufacturing energy from sunlight

H. by removing excess nutrients from the soil

J. by removing predators from the ecosystem





5. Which organisms are most critical in the nitrogen

cycle?

A. plants

B. nitrates

C. animals

D. bacteria





Use the illustration below to answer question 6. The

illustration represents a trophic pyramid.





6. What is the term for the kinds of organisms that make

up the trophic level labeled C?

F. producers

G. consumers

H. detritivores

J. decomposers





Complete the following analogy:

7. bear : omnivore :: vulture :

A. producer

B. herbivore

C. detritivore

D. decomposer





Use the illustration to

answer question 8.

The illustration

represents a food

chain.





8. What role do the krill have in this food chain?

F. They are producers.

G. They are consumers.

H. They are detritivores.

J. They are decomposers.




Short Response

Give two reasons why the destruction of tropical

rain forests can contribute to an increase in

carbon dioxide levels in the atmosphere.




Short Response, continued

Give two reasons why the destruction of tropical

rain forests can contribute to an increase in

carbon dioxide levels in the atmosphere.

Answer: The burning of vegetation releases CO2

into the atmosphere and removes plants that

could have absorbed the CO2 already in the

atmosphere.





Extended Response

Base your answers to parts A & B on the information below.

Some species are generalized with regard to their niche,

and other species are specialized.

Part A Compare the niche of a generalist species with one of a specialist species.

Part B Predict how two different herbivores can share the same plant resource.




Extended Response, continued

Answer:

Part A Generalist species have a broad niche, as they can tolerate a wide range of conditions and use a wide variety of resources. Specialist species can only use specific resources and have more narrowly defined niches.

Part B Two herbivores might eat different parts of the plant, or might eat the plant at different times of the year.




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

• 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.




Chapter 18

Organisms in a Changing Environment,

continued

• Escape from Unsuitable Conditions

– Some species survive unfavorable environmental

conditions by becoming dormant or by migrating.

18 interdependence: a key theme chapter in ecology ... 1 introduction to ecology chapter 18 levels...

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