Community Ecology

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Community Ecology I. Introduction II.
Multispecies Interactions with a Trophic Level
A. Additive Competitive Effects B.
Non-Additive Competitive Effects C. Results
D. Intraguild Predation
arrow go from consumer to food
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arrow go from consumer to food
these three eat each other
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Community Ecology I. Introduction II.
Multispecies Interactions with a Trophic Level
A. Additive Competitive Effects B.
Non-Additive Competitive Effects C. Results
D. Intraguild Predation - eat your competitor!

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Community Ecology I. Introduction II.
Multispecies Interactions with a Trophic Level
A. Additive Competitive Effects B.
Non-Additive Competitive Effects C. Results
D. Intraguild Predation - eat your competitor!
- get a meal and reduce competition!
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Community Ecology I. Introduction II.
Multispecies Interactions with a Trophic Level
A. Additive Competitive Effects B.
Non-Additive Competitive Effects C. Results
D. Intraguild Predation - eat your competitor!
- get a meal and reduce competition! - often
adults eating young of other species
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D. Intraguild Predation - eat your competitor!
- get a meal and reduce competition!
Wissinger, et al. 1993. Intraguild predation in
larval dragonflies
Tramea lacerata
Erythemis simplicicollis
Damselflies - prey
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D. Intraguild Predation - eat your competitor!
- get a meal and reduce competition!
Wissinger, et al. 1993. Intraguild predation in
larval dragonflies
significant non-additive effect
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Community Ecology I. Introduction II.
Multispecies Interactions with a Trophic
Level III. Multispecies Interactions across
Trophic Levels
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Community Ecology I. Introduction II.
Multispecies Interactions with a Trophic
Level III. Multispecies Interactions across
Trophic Levels A. Keystone Predators
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A. Keystone Predators 1. Paine (1966) - the
rocky intertidal
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A. Keystone Predators 1. Paine (1966) - the
rocky intertidal - Pisaster prefers mussels
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A. Keystone Predators 1. Paine (1966) - the
rocky intertidal - Pisaster prefers mussels -
When predators are excluded, mussels outcompete
other species and the diversity of the system
crashes to a single species - a mussel bed
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A. Keystone Predators 1. Paine (1966) - the
rocky intertidal - Pisaster prefers mussels -
When predators are excluded, mussels outcompete
other species and the diversity of the system
crashed to a single species - a mussel bed -
When predators are present, the abundance of
mussels is reduced, space is opened up, and
other species can colonize and persist.
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A. Keystone Predators 1. Paine (1966) - the
rocky intertidal - Pisaster prefers mussels -
When predators are excluded, mussels outcompete
other species and the diversity of the system
crashed to a single species - a mussel bed -
When predator is present, the abundance of
mussels is reduced, space is opened up, and
other species can colonize and persist. So,
although Pisaster does eat the other species
(negative effect) it exerts a bigger indirect
positive effect by removing the dominant
competitor
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A. Keystone Predators 2. Lubchenco (1978)
Littorina littorea feeding on algae
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A. Keystone Predators 2. Lubchenco (1978) -
Snails prefer Enteromorpha to Chondrus - E is
dominant in tide pools, - C is dominant on
exposed rock
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A. Keystone Predators 2. Lubchenco (1978) -
Snails prefer Enteromorpha to Chondrus - E is
dominant in tide pools, - C is dominant on
exposed rock In pools, snails are feeding on the
dominant and you get a keystone effect from low
to intermediate snail densities then they are so
abundant they eat everything.
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A. Keystone Predators 2. Lubchenco (1978) -
Snails prefer Enteromorpha to Chondrus - E is
dominant in tide pools, - C is dominant on
exposed rock In pools, snails are feeding on the
dominant and you get a keystone effect from low
to intermediate snail densities then they are so
abundant they eat everything. On rock, snails
feed on competitive subordinate and Enteromorpha
is whacked by competition AND predation, and
diversity declines with increase snail
abundance.
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A. Keystone Predators 2. Lubchenco (1978) -
Snails prefer Enteromorpha to Chondrus - E is
dominant in tide pools, - C is dominant on
exposed rock In pools, snails are feeding on the
dominant and you get a keystone effect from low
to intermediate snail densities then they are so
abundant they eat everything. On rock, snails
feed on competitive subordinate and Enteromorpha
is whacked by competition AND predation, and
diversity declines with increase snail
abundance. Effects depend on competitive
dynamics, feeding preferences, and densities
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A. Keystone Predators 3. Morin - 1983
Dr. Peter Morin
number of predatory salamanders
Community Ecology
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A. Keystone Predators 4. Worthen - 1989
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Community Ecology I. Introduction II.
Multispecies Interactions with a Trophic
Level III. Multispecies Interactions across
Trophic Levels A. Keystone Predators B.
Apparent Competition
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B. Apparent Competition - consider 2 prey
species consumed by the same predator
PREDATOR
PREY 1
PREY 2
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B. Apparent Competition - consider 2 prey
species consumed by the same predator - suppose
prey 2 increases
PREDATOR
PREY 1
PREY 2
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B. Apparent Competition - consider 2 prey
species consumed by the same predator - suppose
prey 2 increases - this provides more food for
the predator, which increases....
PREDATOR
PREY 1
PREY 2
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B. Apparent Competition - consider 2 prey
species consumed by the same predator - suppose
prey 2 increases - this provides more food for
the predator, which increases.... - and the
other species experiences greater predation...
PREDATOR
PREY 1
PREY 2
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B. Apparent Competition - consider 2 prey
species consumed by the same predator - suppose
prey 2 increases - this provides more food for
the predator, which increases.... - and the
other species experiences greater predation... -
so an increase in one prey causes a decrease in
the other... but this is an indirect effect
mediated through a predator.
PREDATOR
PREY 1
PREY 2
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Community Ecology I. Introduction II.
Multispecies Interactions with a Trophic
Level III. Multispecies Interactions across
Trophic Levels A. Keystone Predators B.
Apparent Competition C. Apparent Mutualism
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C. Apparent Mutualism - consider two prey, each
eaten by specialized predators
Predator 1
Predator 2
Prey 1
Prey 2
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C. Apparent Mutualism - consider two prey, each
eaten by specialized predators - Predator 1
increases and reduces Prey 1.
Predator 1
Predator 2
Prey 1
Prey 2
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C. Apparent Mutualism - consider two prey, each
eaten by specialized predators - Predator 1
increases and reduces Prey 1. - Competition
between prey is reduced and Prey 2 increases
Predator 1
Predator 2
Prey 1
Prey 2
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C. Apparent Mutualism - consider two prey, each
eaten by specialized predators - Predator 1
increases and reduces Prey 1. - Competition
between prey is reduced and Prey 2 increases -
This provides more food for predator 2, which
then increases
Predator 2
Predator 1
Prey 1
Prey 2
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C. Apparent Mutualism - consider two prey, each
eaten by specialized predators - Predator 1
increases and reduces Prey 1. - Competition
between prey is reduced and Prey 2 increases -
This provides more food for predator 2, which
then increases - So, an increase in one predator
has had an indirect positive effect on another
predator.
Predator 2
Predator 1
Prey 1
Prey 2