Download Survival

How does an animal avoid being eaten?
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5/27/08: Behavioral adaptations for survival
Lecture objectives:
1. Be able to generate hypotheses
and predictions
for the adaptive value of a
potential antipredator strategy
2. Recognize the antipredator
benefits that might arise
from living in groups
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Detection
Attack
Capture
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Minimize risk of detection
1.
Must consider
benefits and costs
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Minimize risk of detection
2.
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Minimize risk of detection
2. Crypsis
(morphology & behavior)
African assassin bug
Hypothesis: Assassin bug “backpacking”
is an adaptive antipredator behavior
Predictions?
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Minimize risk of detection
2. Crypsis
(morphology & behavior)
Hypothesis: Catocala relicta (moth) perching
behavior is an adaptive antipredator behavior
Predictions:
1. moth background choice:
2. bird predation:
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Minimize risk of attack
1.
Hypothesis: Anolis lizard push-ups
are honest signal of health
Predictions?
**Human female self-defense strategies**
“Crime victims are frequently chosen because they are easy targets. Criminals prey on
the weak or unsuspecting and usually avoid people who are aware of what’s going on
and might put up a fight. When out in public, look people in the eye, keep your head
up and walk with confidence.” -Realistic Female Self Defense Company
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Minimize risk of attack
2.
Individuals or groups?
Stinging insects
Sawfly larvae
(with eucalyptus oils)
Mobbing behavior: finches vs. hawk
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Minimize risk of attack
3.
Skunks
Poison dart frog
Monarch butterfly
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Minimize risk of attack
a)
4.
Mimic:
a) an aposematic species (Batesian mimicry)
b) a predator of your predator
c) your predator
b) Amazon caterpillar & Mexican vine snake
Model
(acoustical) Mimic:
burrowing owl
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Minimize risk of attack
c) Tephritid fly and
jumping spider
4. Deceive predator (mimicry)
Mimic:
a) an aposematic species (Batesian mimicry)
b) a predator of your predator
c) your predator
Hypothesis: Tephritid fly wing-waving
is an adaptive antipredator behavior
Tephritid fly
Tephritid fly
House fly
Predictions
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Minimize risk of (lethal) capture
1.
Why might an ability to vastly outrun
a predator be unlikely to evolve?
Flight muscle ratio
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Minimize risk of (lethal) capture
2.
Desert gecko
hairstreak butterfly
Hypothesis: Butterfly false heads help prey
survive capture
% escaping
30%
10%
control
False head
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Minimize risk of (lethal) capture
3.
Adelie penguins vs. leopard seal
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Minimize risk of (lethal) capture
3. Aggregate to reduce probability of capture
(dilution effect)
Is there safety in numbers?
The effect of cattle herding on biting risk from tsetse flies.
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Minimize risk of (lethal) capture
4.
A group of individuals whose members use others as
living shields against predators
Position of nest
Snails/nest
Chases/fish/hr.
Center of colony
Edge of colony
Away from colony
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Minimize risk of (lethal) capture
5.
Mean reaction
distance (m)
40
20
0
1
2-10
11-50
>50
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Why do gazelles exhibit stotting behavior?
H1. Alarm signal: Warns conspecifics that predator is near.
H2. Confusion effect: Stotting individuals in a fleeing herd might
confuse/distract a predator so that it can’t focus on one prey
H3. Pursuit deterrence: Stotting advertises that the individual
is in good health and is unlikely to be captured
Prediction
Alarm signal
Confusion
Deter pursuit
Stot when alone
Stot when in groups
Show rump to predator
Show rump to gazelles
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