Download Chapter 54: Community Ecology (with answers)

Chapter 54: Community Ecology
Week 15, Session 1
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Kelsey
Bio 211 (5)
Dr. Holscher
12-7-09
1. What is a community?
a group of populations of different species living close enough to interact
2. Fill in the table of intraspecific interactions:
Competition
+/-, +/+, -/-, or +/0
-/-
Description
Individuals of different
species compete for
resources
One species benefits, the
other suffers
Predation
+/-
Herbivory
+/-
Organism eats a plant
Parasitism
+/-
A parasite benefits, the host
is harmed
Disease
+/-
Mostly affects communities
Mutualism
+/+
Both individuals benefit
Commensalism
+/0
One individual benefits, the
other is neither helped nor
harmed
3. What does the competitive exclusion principle state?
When two species are competing for the same resource in the same community, only one
can survive (unless resource partitioning is used).
4. What does the ecological niche concept state?
When two species have the exact same ecological niche, only one species can survive in
that environment.
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5. __Resource partitioning___________________ makes it possible for similar species to
coexist in the same community.
6. ___Aposematic________________ coloration warns predators to stay away.
7. What is the difference between Batesian and Mullerian mimicry?
Batesian: a non-harmful individual mimics a harmful individual, Mullerian: two harmful
individuals mimic one another
8. How is parasitoidism different than parasitism?
In parasitoidism, the host dies (in parasitism, the parasite wants the host to stay alive).
9. Species richness refers to…
the number of different species
10. Relative abundance refers to…
the number of individuals of each species present
11. True or false: Two communities that have the same richness must have the same
abundance. FALSE
12. Fill in the trophic levels from producers to consumers:
Left to right: primary producer, primary consumer, secondary consumer, tertiary consumer,
quaternary consumer
13. Briefly explain the two competing hypotheses of food chain length:
a. inefficiency of energy transfer limits length
b. dynamic stability hypothesis: longer food chains are less stable
14. What is the maximum number of links a food chain can typically have?
5
15. What is a dominant species?
most abundant or consisting of greatest biomass
16. What is a keystone species?
a species that has a strong central role or niche (ex. otters, urchins, kelp, whales)
17. What is a foundation species?
a species that physically alters the environment, “engineers” (ex. beaver)
18. What does the nonequilibrium model of communities state?
Species are never at equilibrium; they are always dealing with disturbances.
19. What is the difference between primary and secondary succession?
primary: no soil existed before the disturbance, secondary: soil existed before the
disturbance
20. What two biogeographic factors contribute to biodiversity?
solar energy and area