Topic Review Guide: Community Ecology
To Think About: In what ways do interactions between and within populations influence patterns of species
distribution over time? In what ways do interactions between and within populations influence the amount of local
and global ecosystem changes over time?
Watch:
Mr. Andersen’s “Populations” video
Mr. Andersen’s “Niche” video
Mr. Andersen’s “Ecological Succession” video
Mr. Andersen’s “Environmental Matter Exchange” Video
Mr. Andersen’s “Biogeochemical Cycling” Video
Mr. Andersen’s “Ecosystem Change” Video
Read: Chapter 45
Supplementary Resources: Click the links below for more information to help you learn more about this lesson.
 Science Daily: Competitive Exclusion Principle (Gause’s Principle)
 Scitable: Predation, Herbivory and Parasitism
 Scitable: Successional Changes in Communities
 Scitable: Keystone Species
 Ecoplexity.org: Forest Succession Animation
 National Geographic: Keystone Species
 Steve Hammack, Los Gatos HS, California: Community Ecology
 The Open Door Web Site: The Transfer of Energy in A Food Chain
 Kimball’s Biology Pages: Carbon Cycle
 Kimball’s Biology Pages: Nitrogen Cycle
 Discover Biology (Sumanas, Inc. animations): The Phosphorus Cycle
 University of California-San Diego: Greenhouse Effect and Global Warming
 University of California-San Diego: Lake Eutrophication
 Lab Bench: Primary Productivity
 McGraw-Hill: Biological Magnification
Listen and Look: Here is a list of key terms and concepts you will hear about and see during these podcasts and
chapter readings. Get to know them! Be able to connect them to one another using a concept map.
KEY TERMS
Niche
Secondary succession
Symbiosis
Keystone species
Food chain
Trophic levels
Primary productivity
Detritivores
CHNOPS
Greenhouse effect
Lipids
Fundamental niche
Species abundance
Parasitism
Predation
Producers
Autotrophs
Producers
Biomass
Nitrogen fixation
Proteins
Dead zones
Realized niche
Species diversity
Commensalism
Food web
Consumers
Heterotrophs
Consumers
Limiting nutrient
Pyramid of biomass
Carbohydrates
Primary succession
Species richness
Mutualism
Competitive exclusion principle
Decomposers
Primary productivity
Biogeochemical cycles
Eutrophication
Pyramid of numbers
Nucleic acids
Recall and Review: Use the lecture in the video and your textbook reading to help you answer these questions in
your BILL.
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Create a graphic organizer that illustrates the differences between the various types of interspecies
interactions. Describe how these interactions affect population densities of the species involved.
Describe how ecosystems employ feedback mechanisms in order to maintain system homeostasis. Explain
how a predator-prey interaction acts as an example of a negative feedback loop.
The plant kudzu is considered to be an invasive species. Explain how the population of kudzu in the United
States has been brought under control in the Southeast. Describe what other effects the introduction of
a new predator could have on other organisms in the ecosystems where kudzu lives.
Discuss how two organisms that are in direct competition with one another cannot occupy the same niche.
If two organisms attempt to occupy the same niche, what does this lead to?
The competitive exclusion principle states that two species cannot coexist in the same niche with all other
ecological factors held constant. Describe a non-biological example of this principle.
Identify the source of energy for all ecosystems. Explain how each of the following trophic levels obtains
energy from this source:
a. Producers
b. Primary consumers
c. Secondary consumers
d. Decomposers
Explain how and why energy is lost as it moves through ecological communities. How does this affect the
length of food chains?
Using a graphic organizer, describe the similarities and differences between primary and secondary
succession.
Label the food chains at right with the organism names and
trophic level for each.
The producers in the terrestrial food chain (the one on the left
in the diagram) obtain 5 x 106 kJ/m/yr of energy from the Sun.
Using the 10% rule, how much energy do each of the following
organisms get:
a. The mouse
b. The snake
c. The hawk
Create a graphic organizer that illustrates the relationships
between the biogeochemical cycles and each of the biomolecules
(carbohydrates, lipids, proteins, nucleic acids) necessary for life.
Describe the relationship between the cycles and each of these
molecules.
Explain what would happen to the balance of nutrients in an
ecosystem and what the effect would be if the following events
occurred:
a. Nitrate-rich fertilizer runoff accumulated in a river or
lake
b. A large quantity of fish were killed due to a red tide that occurred
c. A coal-burning power plant is built on the outskirts of town
It is said that energy flows through ecosystems, while matter is recycled. Describe how the relationships
demonstrated in food webs illustrate this idea.
14. Describe what your local ecosystem would look like if there were no decomposers. Explain how the absence
of decomposers would alter the populations of:
a) The producers
b) The consumers
15. Explain why the accumulation of toxins is greatest at the highest levels of a food web and what effect this
has on lower levels of the food web.
16. Using the food web shown above, explain what would happen if:
a. The krill were overfished by humans
b. The elephant seal population was hunted to near extinction
c. The population of carnivorous zooplankton experienced a boom
d. The penguins were struck by a virus that killed half the population
17. Explain how the cycling of water is important to the cycling of other materials that are essential for
terrestrial and aquatic ecosystems.
18. Describe why nitrogen often a limiting nutrient for plant growth, even though it comprises over 70% of the
gas in our atmosphere.
19. Explain how the warming of the atmosphere acts as a positive feedback loop, and how this affects the
world’s ecosystems.
20. Describe how global warming has influenced ecosystem richness and biodiversity.
Learn More: For more examples of community ecology principles, use the links below:
 McGraw-Hill: Primary Succession Animation
 Greenriver Community College: Competitive Exclusion Animation
 McGraw-Hill: Niches for Wading Birds
 Prof. Danglais: Food Chain Reaction
 KevinFlint.org: Rainforest Food Chain