Transcript Chapter 20: Community Ecology

Chapter 20
Community Ecology
Table of Contents
Section 1 Species Interactions
Section 2 Patterns in Communities
Chapter 20
Section 1 Species Interactions
Objectives
• Identify two types of predator adaptations and two
types of prey adaptations.
• Identify possible causes and results of interspecific
competition.
• Compare parasitism, mutualism, and commensalism,
and give one example of each.
Chapter 20
Section 1 Species Interactions
Predation
• Predation is an interaction in which one organism
(the predator) captures and eats all or part of another
individual organism (the prey).
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Section 1 Species Interactions
Predation, continued
• Predator Adaptations
– Predators have adaptations to efficiently capture
prey, whereas prey species have adaptations to
avoid capture.
Chapter 20
Section 1 Species Interactions
Predation, continued
• Adaptations in Animal Prey
– Mimicry is an adaptation in which a species gains
an advantage by resembling another species or
object.
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Section 1 Species Interactions
Predation, continued
• Adaptations in Plant Prey
– Many plants produce secondary compounds as a
chemical defense.
Chapter 20
Section 1 Species Interactions
Competition
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Chapter 20
Section 1 Species Interactions
Competition
• Competitive Exclusion
– Competition may cause competitive exclusion,
the elimination of one species in a community.
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Section 1 Species Interactions
Effect of Competition on Two Species of
Barnacles
Chapter 20
Section 1 Species Interactions
Competition, continued
• Character Displacement
– Competition may drive the evolution of niche
differences among competitors. This evolution of
differences in a characteristic due to competition is
called character displacement.
Chapter 20
Section 1 Species Interactions
Competition, continued
• Resource Partitioning
– Differential resource use to avoid competition is
called resource partitioning.
Chapter 20
Section 1 Species Interactions
Warbler Foraging
Zones
Chapter 20
Section 1 Species Interactions
Symbiosis
• Parasitism
– In parasitism, one species (the parasite) feeds
on, but does not always kill, another species (the
host).
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Section 1 Species Interactions
Symbiosis, continued
• Mutualism
– In mutualism, both interacting species benefit.
Chapter 20
Section 1 Species Interactions
Symbiosis, continued
• Commensalism
– In commensalism, one species benefits, and the
other is not affected.
Chapter 20
Section 2 Patterns in Communities
Objectives
• Describe the factors that affect species richness in a
community.
• Explain how disturbances affect community stability.
• Distinguish between types of succession, and
explain why succession may not be predictable.
Chapter 20
Section 2 Patterns in Communities
Species Richness
• Species richness is the number of species in a
community.
• Species evenness is the relative abundance of each
species.
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Section 2 Patterns in Communities
Species Richness, continued
• Latitude and Species Richness
– In general, species richness is greatest near the
equator, and larger areas support more species.
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Section 2 Patterns in Communities
Species Richness, continued
• Species Interactions and Species Richness
– Species interactions such as predation can
promote species richness.
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Section 2 Patterns in Communities
Species Richness, continued
• Community Stability and Species Richness
– Disturbances can alter a community by
eliminating or removing organisms or altering
resource availability.
– Species richness may improve a community’s
stability.
– Areas of low species richness may be less stable
in the event of an ecological disturbance.
Chapter 20
Section 2 Patterns in Communities
Successional Changes in Communities
• Ecological succession is a change in the species
composition of a community over time.
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Section 2 Patterns in Communities
Successional Changes in Communities,
continued
• Primary Succession
– Primary succession is the assembly of a
community on newly created habitat.
– Primary succession occurs in areas that have
been recently exposed to the elements and lack
soil.
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Section 2 Patterns in Communities
Successional Changes in Communities,
continued
• Secondary Succession
– Secondary succession is the change in an
existing community following a disturbance.
– Secondary succession occurs in areas where the
original ecosystem has been cleared by a
disturbance.
Chapter 20
Section 2 Patterns in Communities
The Complexity of Succession
• The traditional description of succession is that the
community proceeds through a predictable series of
stages until it reaches a stable end point, called the
climax community.
• Primary succession typically proceeds from lichens
and mosses to a climax community.
• Secondary succession typically proceeds from weeds
to a climax community.
Chapter 20
Section 2 Patterns in Communities
Ecological Succession at Glacier Bay