Week 5: Anti-predator behavior

Question 1

Swallowtail butterfly

Answer 1

Swallowtail butterflies are middle-to-large in size and very colorful.

The adults are often tailed like the forked tail of some swallows.

Swallowtail butterflies have been the target of butterfly collectors.

Very conspicuous to predators

Question 2

Avian predators

Answer 2

Are diurnal

Have good vision

Are good fliers

—> Avian predators impose direct threats on diurnal butterflies

—> How do butterflies defend themselves against avian predators?

Question 3

Sichuan pepper

Answer 3

widely grown and consumed in Asia as a spice

not related to black pepper or to chili pepper

widely used in the cuisine of Sichuan, China, from which it takes its name

alkaline pH and a numbing effect (toxic) on the lips when eaten in larger doses

Question 4

Chemical defense

Answer 4

Caterpillars of the swallowtail butterflies feed on leaves of the Sichuan trees.

They sequester an extremely potent plant poison in their tissue.

The poison may deter avian predators from attacking swallowtail butterflies and their caterpillars.

Question 5

Osmeterium

Answer 5

is found in the prothoracic segment of caterpillars of swallowtail butterflies

is normally hidden

can be everted when the caterpillar is threatened

used to emit a foul-smelling secretion containing terpenes

Many of terpenes possess qualities that make them ideal active ingredients as part of natural agricultural pesticides

Question 6

Effect of monarch butterfly toxins

Answer 6

Any bird that makes the mistake of trying to eat monarchs usually finds the experience most unpleasant.

After vomiting up a noxious monarch just once, a surviving blue jay will avoid this species thereafter.

Such aversive stimuli are rapidly learned and require only a single trial in most cases.

Question 7

Monarch butterfly

Answer 7

the best known for all North American butterflies

easily recognizable orange and black wing pattern

foul-tasting and poisonous because the caterpillars feed on milkweed

Question 8

Advertising noxiousness

Answer 8

Prey are noxious and have conspicuous colors and patterns,

which make the prey easy to spot.

A learning process in which predators associate noxiousness with conspicuousness is required

Question 9

Aposematism

Answer 9

Conspicuousness associated with distastefulness

Conspicuousness is learned by predators to represent noxious prey

Warning signal: bright colours or loud distinctive sounds associated with prey

Question 10

Examples of warning signals

Answer 10

Coral snakes which are in the same family as cobras possess deadly toxins.

Rattlesnakes rattle and alert the predator of its toxic venom.

Skunks have a black and white pattern and can spray foul-smelling odor.

Question 11

Batesian mimicry

Answer 11

harmless species resembling the warning signals of a harmful species directed at a common predator.

bumblebees are mimicked by hoverflies
honeybees are also mimicked by overflies

Coral snake is poisonous and is mimicked by the milk snake which is harmless

Question 12

Müllerian mimicry

Answer 12

two or more harmful species, that are not closely related and share one or more common predators, have come to mimic each other’s signals.

Both forms advertise their unpalatability with bright colors and areas of high contrast on the body or wings.

monarch butterfly and viceroy butterfly

Question 13

Predator and prey: arms race

Answer 13

Prey are ahead of predator

why?:

1. Life vs. dinner principles
   - Housefly evades dragonfly’s grasp: fly flies for life, dragonfly for dinner.
   - Mistake worse for fly: stronger selection
2. Generation time
   - Often shorter in prey, prey can evolve at a faster rate.
3. Predators often have several prey
   - Predator not sufficiently specialized to drive any one species to extinction

Question 14

Behavioural adaptations for survival

Answer 14

It is hard to pass on your genes when you are dead.

Not surprisingly, most animals are strongly motivated to stay alive long enough to reproduce.

Predators place their prey under intense selection pressure, favoring those individuals with attributes that postpone death until they have reproduced at least once.

Question 15

Stages of predation

Answer 15

Predator selected to complete the sequence successfully

Prey selected to interrupt the sequence

detection –> identification –> approach –> capture –> consumption

Question 16

Stages of predation: detection

Answer 16

Detection of prey as objects which are distinct from the background

antipredator defense:
- Immobility
- Crypsis
- Confusion

Question 17

Crypsis

Answer 17

the ability of an organism to avoid detection by a potential predator

usually most effective when an animal is still.
very common for both prey and predators

relatively low energy cost

A cryptic animal may do this through camouflage, nocturnality, lifestyle, transparency.

camouflage:
is a method of cryptic or concealing coloration that allows an otherwise visible organism or object to remain indiscernible from the surrounding environment through deception.

Ex) Gray treefrog

Question 18

Camouflage vs. mimic

Answer 18

Camouflage requires that the “model” be surroundings.

Mimicry requires that the “model” be another organism.

The distinction is arbitrarily defined:
- Animals that resemble twigs, bark, leaves or flowers are often classified as camouflaged (a plant does constitute the “surroundings”), but sometimes classified as mimics (a plant is also an organism). Either way, the animal is considered cryptic.

Question 19

Does cryptic behavior work?

Answer 19

Blue jays were trained to respond to slides of cryptically colored moths positioned on an appropriate background.

If the jay detected a moth, it pecked at a key, received a food reward, and was quickly shown a new slide.

If the bird pecked incorrectly, it not only failed to secure a food reward, but had to wait a minute for the next evaluation.

Operant conditioning technique

Question 20

Crysis and background selection should match!

Answer 20

Cryptic coloration depends on background selection.

The body coloration of the Australian thorny devil works only when the lizard is motionless in areas littered with bark and other varicolored debris, not on the roads.

Question 21

Confusion

Answer 21

makes detection of a single individual more difficult

Disruptive coloration:
- Patterning to interfere with the perception of the true outline

Question 22

Stages of predation: identification

Answer 22

Identification as profitable or edible prey and decision to attack

antipredator defense :
- Masquerade
- Warning signal
- Müllerian mimicry
- Batesian mimicry
- Honest signaling of unprofitability

Question 23

Masquerade

Answer 23

special resemblance to inedible objects

Young caterpillars (1st – 4th instars): mimics of bird-droppings

the final 5th instar: camouflage

Question 24

Honest singling of unprofitability

Answer 24

stotting

When pursued by a cheetah or lion, this antelope may leap several feet into the air while flaring its white rump patch.

Question 25

Stages of predation: Approach

Answer 25

Approach to attack

antipredator defense:
- Escape by fleeing
- Startle and threat behavior
- Aggregation (dilution effect)

Question 26

Startle behavior

Answer 26

The hawkmoth larva (right) puffs up its head and thorax when disturbed, when then resemble the head of a small poisonous snake (left).

Question 27

The dilution effect in butterfly groups

Answer 27

Butterflies aggregate in large, densely packed groups around mud puddles, where they suck up fluid containing valuable mineral nutrients.

They run the risk of being attacked by various birds.

Individuals in large groups experience a lower risk of predation than those in small groups or by themselves.

Question 28

Stages of predation: Capture

Answer 28

To take by force

antipredator defense:
- Mechanical methods
- Noxiousness
- Group defense

Question 29

Mechanical methods: Autotomy

Answer 29

Autotomy
- Self amputation is the act whereby an animal severs one or more of its own appendages, usually as a self-defense mechanism designed to elude a predator’s grasp.
- The lost body part may be regenerated later.
- Lizards that are captured by the tail will shed part of the tail structure and thus be able to flee. The detached tail will continue to wiggle, creating a deceptive sense of continued struggle and attracting the predator’s attention away from the fleeing prey animal.

Question 30

Noxiousness

Answer 30

Bombardier beetle:
- When physically assaulted, bombardier beetles eject a hot chemical spray from the tip of the abdomen.
- The beetle can aim its spray in virtually any direction.
- The spray of bombardier beetles is ejected at 100°C

Question 31

Group defence in bees

Answer 31

Predatory hornets, Vespa mandarinia, are attacking the honeybee, Apis cerana

More than 500 bees quickly engulf the hornet in a ball

lethal temperature of bees: 48-50 °C
lethal temperature of hornets : 44-46 °C

Question 32

Stages of predation: consumption

Answer 32

consumption: eating

antipredator defense:
- Safe passage through the gut

Ex) sea snails