Unit 2

Question 1

What are search images?

Answer 1

Mental image of prey in a predator’s mind

Question 2

What is crypsis?

Answer 2

The ability of an organism to blend into its environment

Question 3

How can prey increase handling time?

Answer 3

Signal unprofitability through aposematism or pursuit deterrence.

Question 4

Describe the two ways prey can signal unprofitability.

Answer 4

1) Aposematism: toxic colouration
2) Pursuit deterrence: prey seems to hard to catch

Question 5

Why to prey tend to be more “specialized” than predators?

Answer 5

1) Shorter lifespans
2) Life-dinner principle
3) More types of prey, more niches

Question 6

What are the costs to group-living for prey?

Answer 6

1) Increased conspicuousness
2) Increased profitability for predator

Question 7

What are five benefits of group-living for prey?

Answer 7

1) Dilution
2) Cover
3) Confusion
4) Vigilance
5) Group defence

Question 8

What are the costs and benefits of group living in terms of foraging?

Answer 8

Cost: competition
Benefits: Shorter search time, shorter handling time (prey capture)

Question 9

What are the two types of competition?

Answer 9

1) Exploitation: dominant wins best resources
2) Resource defence: dominant guards all the best resources

Question 10

What are the assumptions of the ideal free distribution model? What are the predictions?

Answer 10

It assumes that individuals are free to choose where to go and have equal competitive abilities. It predicts that individuals will go to the area with the highest profitability, competitors do equally well.

Question 11

What are the assumptions and predictions for the despotic distribution model?

Answer 11

It assumes that individuals do not go where the choose and there is unequal competitive ability. It predicts that individuals do not go to max profitability and competitors do equally well.

Question 12

What is the equation describing when animals should contest a resource?

Answer 12

pV-C

p: probability of winning
V: value of resource
C: cost of fighting

Question 13

What conditions lead to costly contests for both individuals?

Answer 13

When competitors have similar V/C = V/C

Question 14

Explain sequential assessment.

Answer 14

The progression of less costly signals to more costly signals as a contest prolongs. Can be highly ritualized.

Question 15

Describe three types of assessment signals

Answer 15

1) Handicap (signals that are too costly to fake
2) Indices (signals that cannot be faked)
3) Status signals (the risk of faking is too high)

Question 16

What is the difference between signals and cues?

Answer 16

Signals are any characteristic that’s function is to be a stimulus to other animals. Cues have a separate function but can be used to gain information about an animal

Question 17

Describe the two routes of signal evolution through ritualization.

Answer 17

Senders manipulate a pre-existing cue to trick receivers. Receivers pick up a new cue. This arms-race leads to signaler-receiver co-evolution

Question 18

What is attenuation? When is it most destructive?

Answer 18

The loss of energy over time/space. Most destructive for high frequency signals.

Question 19

What is degradation? When is it most destructive?

Answer 19

The loss of form due to reverberation. Worse for high frequency, fast-changing signals

Question 20

What types of signal transmission works best in open country versus crowded forest?

Answer 20

Open: broad band and fast changing
Crowded: Low frequency and slow-changing