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Community Ecology
Community Ecology
Community interactions:
Community Ecology
Community interactions:
–Competition
–Predation
–Herbivory
–Parasitism
–Disease
–Mutualism
–Commensalism
–Coevolution
Community Ecology
Community interactions:
–Competition
–Predation
–Herbivory
–Parasitism
–Disease
–Mutualism
–Commensalism
–Coevolution
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Community Ecology
Community structure:
Species diversity
Community Ecology
Community structure:
Species diversity
How many species
are in a community?
Community Ecology
Community structure:
Trophic structure
Who eats whom?
Community Ecology
Community structure:
Primary
producers
Community Ecology
Community structure:
Primary
consumers
Primary
producers
Community Ecology
Community structure:
Secondary
consumers
Primary
consumers
Primary
producers
Community Ecology
Community structure:
Tertiary
consumers
Secondary
consumers
Primary
consumers
Primary
producers
Community Ecology
Quaternary
consumers
Community structure:
Tertiary
consumers
Secondary
consumers
Primary
consumers
Primary
producers
Community Ecology
Community structure:
Energetic hypothesis:
Length of a food chain is limited by
inefficiency of energy transfer
Community Ecology
Community structure:
Energetic hypothesis:
Length of a food chain is limited by
inefficiency of energy transfer
Dynamic stability hypothesis:
Long food chains are less stable
than short food chains.
Community Ecology
Community structure:
Energetic hypothesis:
Length of a food chain is limited by
inefficiency of energy transfer
Dynamic stability hypothesis:
Long food chains are less stable
than short food chains.
Community Ecology
Community structure:
Species with a large impact
Community Ecology
Community structure:
Species with a large impact
•Dominant
•Keystone
•Foundation
Community Ecology
Community structure:
Species with a large impact
•Dominant – most abundant
•Keystone – disproportionate impact
•Foundation – ecosystem engineers
Community Ecology
Community structure:
Bottom-up vs.
top-down controls
Community Ecology
Community structure:
Bottom-up vs.
top-down controls
Predators depend on prey
vs.
Predators control prey
Community Ecology
Community structure:
Disturbance
Community Ecology
Community structure:
Disturbance
May be the norm
Community Ecology
Community structure:
Disturbance
Moderate disturbance may
foster increased diversity
Community Ecology
Community structure:
Disturbance
Human disturbance can be too high
or sometimes too low.
Community Ecology
Community structure:
Ecological succession
Community Ecology
Community structure:
Ecological succession
•Primary – starting with bare rock
•Secondary – starting with soil
Community Ecology
Community structure:
autotrophic prokaryotes
Community Ecology
Community structure:
autotrophic prokaryotes
lichens and mosses
Community Ecology
Community structure:
autotrophic prokaryotes
lichens and mosses
grasses and shrubs
Community Ecology
Community structure:
autotrophic prokaryotes
lichens and mosses
grasses and shrubs
trees
Community Ecology
Community structure:
Pioneer species
Climax species
Community Ecology
Community structure:
Pioneer species
•Facilitate later species
Climax species
•Inhibit later species
Community Ecology
Community structure:
births - deaths
r = ----------------------N
Community Ecology
Community structure:
births - deaths
r = ----------------------N
ΔN
------- = rN
Δt
Community Ecology
Community structure:
births - deaths
r = ----------------------N
ΔN
K-N
------- = rN (-----------)
Δt
K
Community Ecology
Community structure:
r-strategies
K-strategies
Community Ecology
Community structure:
r-strategies
•Rapid growth without competition
K-strategies
•Maxium population with crowding