Transcript Avoiding Predation

AVOIDING PREDATION
• HOW NOT TO BE FOOD •
Avoiding Predation
Blue petrel
Brown Skua
Avoiding Predation
Petrel courtship
calls
Attracts skua
Petrels detect skua
Petrels emit skua territorial call
Cease courtship
Avoiding predation
Frog hatching times - Red-eyed tree frog - Agalychnis callidryas
Avoiding predation
Frog hatching times - Red-eyed tree frog - Agalychnis callidryas
Avoiding predation
Frog hatching times - Red-eyed tree frog - Agalychnis callidryas
Wasp & snake
predators
Tadpoles hatch
and drop into
water
Fish + insect
predators
Eggs on underside of
leaves
Avoiding predation
Frog hatching times
Avoiding predation
Frog hatching times
If predation is absent
-hatch slowly
Proportion
hatched
Consequence:
Tadpole is large enough to
avoid fish predation
Day 4
Day 5
Day 6
Avoiding predation
Frog hatching times
If predation is strong
Hypothesis: Eggs should hatch earlier
Clutches under wasp predation
Clutches under no predation
Proportion
hatched
Age of clutch
Avoiding predation
Frog hatching rates
If predation is strong
Hypothesis: Eggs should hatch faster
Clutches under wasp predation
Clutches under no predation
Hatch rate
(egg/min)
Age of clutch
Avoiding predation
Frog hatching times
If predation is strong
Hypothesis: Eggs should hatch earlier
With snake
predator
With no
predator
% hatched
Time (days)
ALARM CALLS - VERVET MONKEYS
VERVET CALLS
Look up
Stand up
and search
grass
Group and hide
in bushes
Avoiding Predation
1. Escape and Freezing
Crypsis
Avoiding Predation
2. Deception
Avoiding Predation
2. Deception - disruptive colouration
Butterfly fish
Avoiding Predation
3. Toxicity and aposematism
Poison arrow frogs
Avoiding Predation
3. Mimicry - Batesian
Look like something distasteful
Viceroy
Monarch
Avoiding Predation
Mimicry - Müllerian
A number of distasteful animals resemble one another
Avoiding Predation - Group Effects
And some of the benefits of being in groups
a. Encounter Effect
Grouped animals
are more difficult to find
Avoiding Predation - Group Effects
And some of the benefits of being in groups
b. Dilution Effect
1:9
1:1000’s
Groups and Predator Inspection
Sometimes prey approach predators
-called inspection, harassment, mobbing, boldness
Why?
1. Decrease current risk
2. Information gathering about threat
3. Warn other group members
Groups and Predator Inspection
Herds from <10 to >500
Groups and Predator Inspection
Probability of
group
approaching
predator
0
200
400
Group size
600
Groups and Predator Inspection
4000
Distance cheetah
walked away
from group (m)
3000
2000
1000
0
0
200
400
Group size
600
Groups and Predator Inspection
Stotting
Stotting video
Groups and Predator Inspection
Possible Function
Relevant information
1. Alarm signal
- isolated animals stott
2. Social cohesion
- orient rump to predators
3. Confusion effect
- isolated animals stott
4. Pursuit deterrence
Groups and Predator Inspection
With stotting
Hunt abandoned
Chase failed
Gazelle killed
Without stotting
Predator/Prey Arms Races
Red Queen Hypothesis
"Well, in our country," said Alice, still panting a little, "you'd
generally get to somewhere else — if you run very fast for a long
time, as we've been doing."
"A slow sort of country!" said the Queen. "Now, here, you see, it
takes all the running you can do, to keep in the same place. If you
want to get somewhere else, you must run at least twice as fast as
that!"
For an evolutionary system, continuing
change is needed just so that one species
can maintain its fitness relative to the
species with which it is co-evolving.
Predator/Prey Arms Races
Red Queen Hypothesis
Example: Passiflora and Heliconius
Passiflora
Heliconius
Predator/Prey Arms Races
Red Queen Hypothesis
Example: Passiflora and Heliconius
Develops chemical defenses
Develops chemical resistance
Develops egg mimicry
?
Predator/Prey Arms Races
Red Queen Hypothesis
Example: Passiflora and Heliconius
Egg Mimicry
Heliconius eggs
Passiflora egg mimic