AVOIDING PREDATION

• HOW NOT TO BE FOOD •

Avoiding Predation

Blue petrel Brown Skua

Avoiding Predation

Petrel courtshipcalls

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

Eggs on underside of leaves

Tadpoles hatch and drop into water

Wasp & snake predators

Fish + insect predators

Avoiding predation

Frog hatching times

Avoiding predation

Frog hatching times

If predation is absent-hatch slowly

Day 4 Day 5 Day 6

Proportion hatched

Consequence:Tadpole is large enough to avoid fish predation

Avoiding predation

Frog hatching times

If predation is strong

Hypothesis: Eggs should hatch earlier

Age of clutch

Proportion hatched

Clutches under wasp predation

Clutches under no predation

Avoiding predation

Frog hatching rates

If predation is strong

Hypothesis: Eggs should hatch faster

Age of clutch

Hatch rate(egg/min)

Clutches under wasp predation

Clutches under no predation

Avoiding predation

Frog hatching times

If predation is strong

Hypothesis: Eggs should hatch earlier

% hatched

Time (days)

With snake predator

With no predator

ALARM CALLS - VERVET MONKEYS

Look up

Group and hide in bushes

Stand up and searchgrass

VERVET CALLS

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

Mimicry - Müllerian

A number of distasteful animals resemble one another

Avoiding Predation

Avoiding Predation - Group Effects

And some of the benefits of being in groups

a. Encounter Effect

Grouped animalsare 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

Group size

0 200 400 600

Groups and Predator Inspection

Distance cheetah walked away from group (m)

Group size

0 200 400 600

4000

3000

2000

1000

0

Groups and Predator Inspection

Stotting

Stotting video

Possible Function

1. Alarm signal

2. Social cohesion

3. Confusion effect

4. Pursuit deterrence

Relevant information

- isolated animals stott

- orient rump to predators

- isolated animals stott

Groups and Predator Inspection

Hunt abandoned

Chase failed

Gazelle killed

With stotting

Without stotting

Groups and Predator Inspection

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 resistance

Develops chemical defenses Develops egg mimicry

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Predator/Prey Arms Races Red Queen Hypothesis

Example: Passiflora and Heliconius

Egg Mimicry

Heliconius eggs

Passiflora egg mimic