Download 14.2

Study Guide 14.2: Community Interactions
Key Concept: Organisms interact as individuals and in populations.
Vocabulary (Define and give a real world example for each)
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Competition (Interspecific and Intraspecific – define both)
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Predation
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Symbiosis
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Mutualism
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Commensalism
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Parasitism
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Coevolution (Page 349 in your book) - the process in which two or more species evolve genetically (changes
to genes) in response to interactions with one another.
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Evolutionary Arms Race - a type of coevolution in which each species responds to pressure (often a
predator/prey relationship) from the other through better adaptations over many generations.
Review Questions
1.
During the fall spawning of salmon, grizzly bears compete over space on the banks of a river. What type of
competition is this?
Intraspecific competition
2.
The term symbiosis comes from a Greek term meaning living together. How does this word origin help to
explain the definition of symbiosis?
Symbiosis is an ecological relationship between members of at least two different species that live together
in direct contact.
3.
Describe and give examples of three types of symbiosis.
Mutualism - an interspecies interaction in which both species benefit from one another.
Ex. The leaf cutter ants and the fungus they cultivate and harvest (we will see a video on this). They
depend completely on one another.
Commensalism - An association between two organisms in which one benefits and the other derives neither
benefit nor harm.
Barnacles and whales or humans and our hair follicle mites.
Parasitism - A non-mutual symbiotic relationship between species, where one species, the parasite, benefits
at the expense of the other, the host
4.
Deer and deer liver flukes or humans and trypanosomes (tropical protozoan – Chagas disease)
Use your knowledge of the word mutual to write a definition for mutualism.
Mutual refers to a relationship where both (or all) parties benefit. Mutualism is a symbiotic relationship in
which both organisms (e.g. leaf cutter ants and their fungi) benefit.
5.
6.
For each type of symbiotic relationship, complete the chart with details about how each organism is
impacted using the terms “Benefits,” Harmed,” or “No Impact.” For each situation, assume that Organism A
initiates the relationship.
Symbiotic Relationship
Mutualism
Organism A
Benefits
Organism B
Benefits
Commensalism
Benefits
No impact
Parasitism
Benefits
Harmed
How is parasitism similar to and different from predation?
Both refer to relationships in which one organism benefits and the other is harmed/eaten. Parasitism,
unlike predation, is a symbiotic relationship in which the two organisms live in direct contact with one
another (e.g. a tick sucking blood or malaria). Such close contact is not necessary for predation.
7.
What is the difference between endoparasites and ectoparasites?
Endoparasite lives inside of host. Ectoparasite lives on the outside of host.