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CHAPTER
5
Evolution and Community
Ecology
Lesson 5.2 Species
Interactions
The zebra
mussel has
completely
displaced 20
native
mussel
species in
Lake St.
Clair.
Lesson 5.2 Species Interactions
The Niche
•
Describes an organism’s use of resources and functional
role in a community
•
Affected by an organism’s tolerance—its ability to survive
and reproduce under changing environmental conditions
•
Often restricted by competition
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Lesson 5.2 Species Interactions
Competition
• Organisms compete
when they seek the
same limited resource.
• In rare cases, one
species can entirely
exclude another from
using resources.
• To reduce competition,
species often partition
resources, which can
lead to character
displacement.
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Resource Partitioning
Lesson 5.2 Species Interactions
Predation (+/–)
•
The process by which a
predator hunts, kills, and
consumes prey
•
Causes cycles in predatory
and prey population sizes
•
Defensive traits such as
camouflage, mimicry, and
warning coloration have
evolved in response to
predator-prey interactions.
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• Some predator-prey
relationships are
examples of
coevolution
– the process by which
two species evolve in
response to changes
in each other.
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Did You Know? A single rough-skinned newt contains
enough poison to kill 100 people. Unfortunately for the
newt, its predator, the common garter snake, has
coevolved resistance to the toxin.
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Lesson 5.2 Species Interactions
Parasitism and Herbivory
(+/–)
• Parasitism: One
organism (the parasite)
relies on another (the
host) for nourishment or
for some other benefit
• Herbivory: An animal
feeding on a plant
Hookworm (a parasite)
Did You Know? One study of Pacific estuaries
suggests that parasites play an important role in
keeping these ecosystems healthy by controlling host
populations.
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Lesson 5.2 Species Interactions
Mutualism (+/+) and
Commensalism (+/0)
Lichen: a symbiotic relationship
between a fungus and a photosynthetic
partner, such as an alga
•
Mutualism: a
relationship in which two
or more species benefit
•
Commensalism: a
relationship in which one
species benefits while
the other is unaffected
Did You Know? Symbiosis describes a long-lasting and physically close
relationship between species in which at least one species benefits.
M
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QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
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C
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• http://www.youtube.com/watch?v=8YKA
alZAqO4 Rhino song
• http://www.youtube.com/watch?v=uxVM
eLWzB_o