Chapter 12- Antipredator behavior

Question 1

Annelid worms predator defense

Answer 1

These worms produce bioluminescent sacs (bombs) that they release when encountering new predators. The bombs startle the predator and allow the worms to escape. The sacs are homologous with other known anatomical structures in worms without the sacs, so researchers have an idea what structure the sacs are derived from

Question 2

Larval Hymenoptera antipredator behavior

Answer 2

They secrete a viscous compound through cavities on their cuticles when they encounter a predator. The compound is composed of many chemicals that glue together the predator’s appendages

Question 3

Why should natural selection operate strongly on antipredator behavior?

Answer 3

Successful antipredator behavior is crucial if an individual is going to have any reproductive success

Question 4

2 types of antipredator behaviors

Answer 4

1. Behavior that helps prey avoid detection by predators
2. Behavior that function when a prey encounters a predator

Question 5

3 ways that animals can avoid predators

Answer 5

1. Blending into the environment
2. Being quiet
3. Choosing safe habitats

Question 6

Cryptic matching

Answer 6

Animals can avoid predators by cryptic matching to the environment, which makes detection by predators less likely. This might not be behavioral, mice are an example of species that blend into the environment based on their fur color. However, squids and octopuses can change their color at will to hide from predators

Question 7

Nocturnal behavior of Australian cuttlefish study

Answer 7

Cuttlefish camouflaged themselves in 86% of nocturnal observations. Cuttlefish could match their background in one of 3 ways, and they could change their color and pattern in a matter of seconds.

Question 8

3 types of crypsis in cuttlefish

Answer 8

1. Uniform pattern where the cuttlefish has a single skin color that matches their background- this was rare
2. Mottled pattern- cuttlefish had small dark and light patches that mimicked the background, usually in locations with small rocks and dark algae. This was more common
3. Disruptive camouflage- the cuttlefish takes on light and dark stripes- disrupts the animal’s body so it doesn’t look like cuttlefish

Question 9

Gulf toadfish antipredator behavior

Answer 9

Toadfish are preyed on by dolphins that orient toward the boat whistle sound the toadfish make. Toadfish were monitored while they were exposed to dolphin sounds- one of which was a sound associated with foraging. Male toadfish exposed to dolphin foraging sounds reduced their call rates by 50% and maintained this rate for 5 minutes following exposure. They also exhibited an increase in cortisol. Males in other treatments did not exhibit the same changes.

Question 10

Co-evolution

Answer 10

When changes to traits in species 1 lead to changes to traits in species 2, which in turn feeds back to affect traits in species 1, and the trend continues. There is usually co-evolution between predators and prey, creating an evolutionary arms race as predators evolve detection systems to find prey and prey evolve mechanisms to protect themselves from predators

Question 11

Predation and choice of nesting sites in parrots

Answer 11

Researchers used phylogenetic data to determine that the ancestral state of nesting behavior in parrots was tree cavity nesting, rather than in other cavities. There are selective forces driving nesting in other cavities- there is intense competition for nests in trees due to manmade pressures, and predation on chicks is high during the nesting period- shifting to other locations could decrease predation pressure

Question 12

Translocation programs in rabbits

Answer 12

When exposed to olfactory cues from predators that were similar to predators that rabbits evolved with, the rabbits responded with adaptive antipredator behaviors. When exposed to olfactory cues from quoll, rabbits did not display antipredator behaviors and were susceptible to predation

Question 13

When a predator is encountered, what neuroendocrinological changes occur in mice?

Answer 13

The frontal cortex may alter neurological and endocrinological responses to stressors- this area regulates the effects of stressors on behavior in rodents and humans. Researchers exposed one group of mice to the odor of a predator and another group to physical stress. It was found that both predator odor and physical stress increased the circulation of acetylcholine, serotonin, and dopamine in the frontal cortex, but the increase was greater with predator odor. When given an anti anxiety drug and then exposed to a predator, the neurotransmitter increases disappeared. This suggests that predators can cause anxiety.

Question 14

5 behaviors that prey use once they encounter a predator

Answer 14

1. Fleeing
2. Approaching a predator to obtain information
3. Feigning death
4. Signaling to the predator
5. Fighting back

Question 15

Flight initiation distance

Answer 15

How close a predator can approach before prey flee.

Question 16

Which factors influence flight initiation distance?

Answer 16

When animals are far from their territory/place of safety, they will flee from a predator sooner. Animals involved in foraging, mating, or fighting are slower to flee from predators because they are less alert to predation. The predator’s size, speed, and directness of approach affected the prey’s decision to flee, and morphological traits of the prey also affected the decision. The presence of armor, like shells, reduced flight initiation distance, as did the prey’s ability to camouflage itself. Learning also affected the decision

Question 17

How does learning affect flight initiation distance?

Answer 17

Prey flee at a greater distance as a function of experience with predators

Question 18

Genetics of schooling behavior in sticklebacks

Answer 18

Sticklebacks from open water habitats encounter more predators and school more tightly than sticklebacks from more vegetated environments. Fish from open water environments also angle themselves differently when schooling. Researchers examined whether genetic variation caused the phenotypic differences in schooling behavior. They inserted a genetic promoter of the Eda gene into fish from benthic (vegetated) populations. These fish then exhibited schooling behavior similar to fish from open water (pelagic) environments. Variation in the Eda gene likely explains the differences in schooling behavior

Question 19

What embryo fleeing behavior is exhibited in red eyed treefrogs?

Answer 19

Treefrogs attach their eggs to vegetation that hangs over water, so tadpoles drop into their aquatic habitat when the eggs hatch. Embryos and tadpoles have different sets of predators because they have different environments. Weak predation from snakes and wasps means that eggs hatch late in the season- it lengthens an embryo’s time in a low predation habitat and allows the embryo to grow to a size that helps them avoid aquatic predation

Question 20

How does embryo fleeing behavior in red eyed treefrogs vary with predation levels?

Answer 20

Researchers predicted that treefrog eggs would hatch sooner if predation in the terrestrial environment increased- survival rates would probably increase if embryos could quickly leave a high predation environment. Researchers observed clutches of eggs and found that eggs hatched earlier when their clutch had been exposed to wasp predation. These eggs hatched at 4 or 5 days compared to the 6 days of undisturbed eggs. Some disturbed eggs even hatched immediately following attacks

Question 21

Role of the amygdala in fear

Answer 21

The amygdala plays a role in the conditioned fear response. Activity in this area of the brain increases as fear conditioning occurs. Damage to the amygdala causes a reduction in the behaviors typically produced by conditioned fear responses

Question 22

Heritability of conditioned fear responses

Answer 22

Studies in rodents have found evidence for the heritability of conditioned fear responses. Artificial selection experiments have found strong responses to the selection pressure applied, which suggests an underlying heritability to antipredator behaviors

Question 23

What cues do red treefrog embryos use to determine when they hatch?

Answer 23

Researchers hypothesized that embryos use vibration cues associated with snake attacks as a proximate cue for when to hatch. Researchers recorded vibrational noises and played them for embryos- one noise was recorded from a snake. The cues associated with snakes resulted in treefrogs that hatched earlier than treefrogs that had been played the other cues.

Question 24

Approaching predator behavior

Answer 24

Some animals approach predators to gain more information about the predator. Approach behavior is characterized by a series of moves toward the predator that are interrupted by stationary pauses. The prey might end up retreating, joining a social group, or attacking the predator. This is often a parental behavior to protect offspring

Question 25

Costs and benefits of approach behavior in Thomson’s gazelles study

Answer 25

There is some evidence for a decrease in risk of predation. Cheetahs responded to gazelle approach behavior by moving farther between rest and hunting periods and potentially leaving the area sooner

Question 26

3 benefits of approaching a predator

Answer 26

1. Decrease the risk of predation
2. Allow gazelles to gather information about a potential threat
3. Serve to warn other group members of the potential danger associated with predators

Question 27

Costs of approach behavior

Answer 27

Lost time and energy- gazelles spend 4% of their waking hours on approach behavior

Question 28

Tonic immobility

Answer 28

When an insect fakes death (thanatosis) in response to a predator. It falls to the ground and remains completely still. Some animals remain conscious, others don’t. This works because predators usually prefer live prey

Question 29

Death feigning in the adzuki bean beetle

Answer 29

When a predator approaches, a beetle can either fake death or fly away, but it can’t do both at the same time. Researchers hypothesized that there is a negative genetic correlation between the intensity of death feigning and the ability to fly- beetles that faked death for a long period of time would be poor flyers. Researchers tested beetles on their length of time feigning death in response to danger, and their flying abilities. They then conducted artificial selection based on the beetle’s feigning death abilities and flying abilities. Beetles in the long duration line, with the longest duration of death feigning, were allowed to mate with each other, as were the short duration line. After 8 generations, beetles in the long duration line showed death feigning behavior 40 times as long as those in the short duration line. In addition, there was a negative correlation between death feigning and flying abilities. There was also a negative correlation when individuals with different flying abilities underwent an artificial selection study

Question 30

Proximate basis of death feigning in beetles

Answer 30

Beetles in populations selected for long bouts of death feigning had higher brain concentrations of dopamine than beetles from populations selected for short bouts of death feigning.

Question 31

Why do prey sometimes signal to predators?

Answer 31

To warn the predator of the dangers of contact, or that it has been sighted and may not succeed in capturing a prey. Signals are usually visual but can be auditory.

Question 32

Warning coloration in monarch butterflies

Answer 32

When they are caterpillars, monarch butterflies ingest cardiac glycosides. These compounds are not toxic to monarchs but can be toxic to birds. Monarchs store the compounds, so birds will become sick from eating a monarch butterfly. Birds have learned to associate monarch colors with illness

Question 33

How could natural selection promote warning coloration in monarchs, if a monarch has to die for predators to learn about the danger?

Answer 33

If prey live in groups, warning coloration could preferentially aid genetic relatives, so it would therefore be favored by natural selection. Another explanation is that predator does not always kill the monarch before it senses the toxin

Question 34

Tail flagging in ungulates

Answer 34

Individuals (like deer) flag their tails after a predator has been sighted as a series of antipredator behaviors. When individuals raise their tails, they flash a conspicuous patch of white fur. Flagging often occurs when the prey is at a safe distance from the predator

Question 35

Functions of tail flagging (6)

Answer 35

1. Warn other members of the species about the predator
2. Close ranks and tighten group cohesion, making predation less likely
3. Pursuit deterrence hypothesis
4. Cause other group members to engage in various antipredator activities, confusing the predator
5. Serve as a sign for appeasing dominant group members, so it only plays a secondary role in antipredator behavior
6. Entice the predator to attack from a greater distance, which could result in a failed attempt at capture

Question 36

Pursuit deterrence hypothesis

Answer 36

A signal to the predator that it has been sighted and should abandon any attack

Question 37

Pursuit deterrence hypothesis study (Caro)

Answer 37

Researchers found that white tailed deer that run fast flag their tails and use this signal to communicate to the predator that an attack is unlikely to succeed because the fleeing deer will escape the predator. This behavior also occurs in species other than deer.

Question 38

How do beetles create an acidic spray to defend against predators?

Answer 38

Beetles shoot predators with an acidic spray- they can shoot the spray 20 times. The beetles have 2 glands that each have two separate compartments. One compartment (the reservoir) contains hydroquanines and hydrogen peroxide, and the second compartment (the reaction chamber) contains catalases and peroxidases. When beetles are threatened by a predator, they mix the two compartments and create an acidic spray of p-benzoquinones. The predators are injured by the spray without the beetles being harmed. Some beetles are able to aim the spray at predators, based on the direction they are being attacked from

Question 39

How did the chemical spray mechanism evolve in beetles?

Answer 39

Meritus contractus is the oldest bombardier beetles species. It also contains the glands with the compartments containing chemicals to make the spray. This suggests that possession of these traits is ancestral. However, this species discharged the spray as a mist rather than the jet, like current beetles species. When attacked from the rear, meritus contractus produces a froth secretion that builds up in the body and wards off predators. When attacked from the front, the froth is pushed forward along tracks on its forewings. This action reduces the temperature of the spray.

Question 40

Mobbing

Answer 40

When a flock of blackbirds sees a predator, they join together, fly toward the danger, and aggressively attempt to chase it away

Question 41

Mobbing and cultural transmission in blackbirds study

Answer 41

Researchers had a model bird and a naive bird, each in its own aviary. They designed the experimental apparatus so that each blackbird could see a noisy friarbird- neither blackbird had seen this type of bird before. The naive blackbird saw the friarbird alone, but the model saw the friarbird and an owl adjacent to it- the owl is a predator of blackbirds. When the model mobbed the owl, the naive bird saw it mobbing a friarbird. Researchers found that naive birds were more likely to mob the friarbird if they were not exposed to the model- this indicates cultural transmission. Researchers also found that cultural transmission chains could be 6 birds long.

Question 42

What trade offs might have to occur with antipredator behavior?

Answer 42

The time that animals spend doing antipredator behavior could be spent doing something else. Antipredator behavior could also create pressure to perform other behaviors in a specific manner, like foraging in the vicinity of a refuge. Predation impacts when a forager begins feeding, when it resumes feeding after being interrupted, where it feeds, what it eats, and how it handles its prey

Question 43

What behavior trade offs occur in squirrels?

Answer 43

Squirrels alter their foraging choices as a result of predation pressure from redtailed hawks. The closer the refuge from predation, the more likely squirrels were to use shelter when foraging. Squirrels were more likely to run to safety if it would take a short amount of time. Also, squirrels were more likely to carry larger items to safe areas before continuing to forage.

Question 44

Foraging behavior in squirrels study

Answer 44

Researchers presented squirrels with either a small piece of cookie or a large piece of cookie. The profitability of small food items was greater than the profitability of large food items- squirrels always take small items in the absence of predation. Total handling time with larger food items was great enough that larger items should be brought to cover before being eaten, if the distance to cover is short. Researchers hypothesized that squirrels might pass up smaller, more profitable food items to search for larger food items to bring to cover if faced with predation. The results were consistent with the hypothesis

Question 45

Cryptic coloration

Answer 45

Blending in- depends on where the animal chooses to rest. The Australian thorny devil is camouflaged only when the lizard is motionless in areas littered with bark and other varicolored debris, not on roads. Most animals that use this strategy are diurnal (awake during the day).

Question 46

Cryptic coloration in moths

Answer 46

The moth Biston betularia comes in two forms, the “typical” salt-and-pepper morph and the melanic (black) type. The typical form decreased between 1850 to 1950. Birds would find and remove moths on tree trunks more than on limb joints. Melanic forms were less often discovered by birds in polluted (darkened) woods, while typical forms “survived” better in unpolluted woods

Question 47

Conspicuous aposematic (warning) coloration

Answer 47

Often used by noxious organisms to signal their unpalatability to potential predators. Blister beetles are one example- they have blood laced with cantharidin, a highly
noxious chemical

Question 48

Warning coloration in mammals

Answer 48

Skunks and crested porcupines are examples. Their defenses include sharp spines and anal gland secretions. These animals usually live in more exposed areas

Question 49

Costs of cryptic behavior (2)

Answer 49

1. Time and energy that individuals use to find the right background upon which to rest.
2. Time spent immobile during day when diurnal predators might spot them

Question 50

An animal’s decision to flee depends on (6)

Answer 50

1. Distance between predator-prey
2. Distance to shelter
3. The presence of an armor (spines, shells)
   4 Degree of crypsis
4. Other morphological traits (age, fitness)
5. Experience with predator avoidance