AP Biology
Ecology TRG #3
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:
First: Mr. Andersen’s “Populations” video
Second: Mr. Andersen’s “Niche” video
Last: Mr. Andersen’s “Ecological Succession” video
Read:
Ch. 41 – Biology in Focus
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
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
Ecological efficiency
Fundamental niche
Species abundance
Parasitism
Predation
Producers
Autotrophs
Realized niche
Species diversity
Commensalism
Food web
Consumers
Heterotrophs
Primary succession
Species richness
Mutualism
Competitive exclusion principle
Decomposers
Primary productivity
Recall and Review: Use the lecture in the video and your textbook reading to help you answer these questions
in your BILL.
1. 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.
2. 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.
3. 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.
4. 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?
5. 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.
6. 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
7. Explain how and why energy is lost as it moves through ecological communities. How does this affect
the length of food chains?
8. Using a graphic organizer, describe the similarities and differences between primary and secondary
succession.
9. Label the food chains at right with the organism names and trophic
level for each.
10. 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
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