Animal Signalling

Question 1

What are some examples of animal signalling?

Answer 1

Sign stimuli
Peacock tail
Sensory perception
Signals that communicate quality of information to each other

Question 2

What is a signal if it benefits the signaller?

Answer 2

Some signals benefit the signaller and are therefore adaptive

Question 3

What are the signals of they do not benefit the signaller?

Answer 3

Some signals are not beneficial to the signaller and are therefore maladaptive

Question 4

Give some examples of adaptive signals

Answer 4

Distress calls that result in help
Warnings that result in challenges being withdrawn
Courtship displays that result in successful mating

Question 5

Give examples of maladaptive signals

Answer 5

Signals that attract predators

Displays of fitness that fail to impress potential challengers or mates

Question 6

True or false

Maladaptive signals usually get passed onto the next generation

Answer 6

False

Maladaptive signals usually do not get passed onto the next generation

Question 7

What does natural selection do to signals?

Answer 7

Natural selection causes beneficial signals to become exaggerated and harmful ones to disappear or be revealed only when safe
If the harmful signal evolves to be revealed when safe then it would also encourage the evolution of better assessment skills so the signaller knows when it’s safe to use it

Question 8

When signaling what are both parties respectively known as?

Answer 8

The individual sending out the signal is referred to as the signaller
The individual receiving the signal is referred to as the receiver
The animal receiving the signal is known as the receiver regardless of whether it is an intended receiver or unintended receiver

Question 9

Can there be more than 1 receiver?

Answer 9

Yes

Question 10

Male peacocks use their tail feathers to send signals to the female peahen, but who else can be a receiver?

Answer 10

There are unintended receivers of the male peacock such as predators that would receive the male peacock’s signals and potentially see a hunting opportunity

Question 11

Give an example of a signal being intercepted

Answer 11

An example of this is that ants lay a pheromone trail when they find food and explore so other ants can follow it
However a small species of snake can now also detect the same molecules used by the ants to make trails to find the ants nest and eat the ant larvae

Question 12

What is an odour or scent molecule known as if it’s used for interspecies communication?

Answer 12

When an odour or scent molecule is used for interspecies communication it’s known as a kairomone

Interspecies = existing or occuring between species

Question 13

Does context matter in animal signalling?

Answer 13

Yes
Animals pay attention to the context of a situation and have various different ways so that the right receiver gets the signal
Due to this it allows signals to be made in the correct context

Question 14

Can animals adjust how long signals last for?

Answer 14

Yes

Question 15

Give some examples of scents being used to communicate with

Answer 15

Smaller volatile molecules are used in odours for rapid signals that disperse rapidly
An example of a use for these odours are alarm odours

Heavier molecules are often ‘sticky’ and are used in odours used for longer lasting messages
An example of a use for these odours are territorial markings

Question 16

With vocal signals what can animals alter?

Answer 16

With vocal signals animals have the opportunity to alter signal volume based on the situation

Question 17

Give examples of how an animal can alter vocalisations

Answer 17

Animals have different vocalisations for when the sounds needs to travel far
Making the vocalisation louder can do this
Also in some cases lower pitched noises can travel farther

Animals will produce quieter vocal signals if the desired receiver is close by because it saves energy and avoids being overheard by undesirable receivers

Sound signals will also be more salient if they differ in pitch from the background noise
Salient = most noticeable or important
In some cases it can save energy to change the vocalisations pitch instead of its volume

Question 18

Signals always occur against a background which can make the signal easier or harder to distinguish from other sounds
What kind of signal do receivers more easily detect?

Answer 18

Due to this receivers can more easily detect signals that differ from background sensory stimuli

Question 19

What does signal detection theory focus on?

Answer 19

Signal detection theory is about how the signal differs from the background

Question 20

Explain the basic principles of signal detection theory

Answer 20

The background stimuli will contain a range of stimuli which may be normally distributed
Most of the background stimuli will occur around the mean of the background stimuli range
Due to this animal signals will be a stimuli that is not a stimulus similar to the mean background stimuli
It makes it more easier to detect the stimulus this way

Receivers have also evolved to detect the right signals too
Due to this receivers will have a certain sensitivity that maps onto those signals that are most critical for their fitness
The receivers are most sensitive to fitness-critical signals

Receivers will also have a certain bias for sounds
If there is a large cost to missing the signal they will be biased towards responding to a signal even if it is faint
If there is a large cost to false alarms they will be biased towards responding to the signal only when it is very clear
Depending on whether costs are worse for a false alarm or missing it the receiver will be biased towards accepting signals when they’re slightly ambiguous

Question 21

Explain how camouflage fits into signal detection theory

Answer 21

Camouflage is linked to signal detection theory because animals habituate to sensory information from the background environment
Signallers camouflage themselves because if they’re seen they’ll be harmed by being eaten or being unable to catch prey
Signallers who would be harmed if detected therefore do well if they match the background
This means that camouflaged signallers are camouflaged to avoid signalling

Question 22

How do animals stands out from the crow?

Answer 22

Some animals are very salient/conspicuous

Other animals are highly camouflaged but will produce salient signals in certain contexts

Question 23

Animals usually produce highly salient signals to advertise something, like what?

Answer 23

Their fitness to potential mates

How distasteful and/or poisonous they are

Question 24

Why do animals use salient signals?

Answer 24

Animals usually produce highly salient signals to advertise something

Sometimes salient signals can be a shock or scare tactic to scare predators away

Question 25

Animals can only be salient under what circumstances?

Answer 25

Animals can only be salient if the stimulus varies from the background stimuli

Question 26

What does aposematic mean?

Answer 26

Aposematic = denoting colouration or marking serving to warn or repel predators

Question 27

How does aposematic colouration work?

Answer 27

Once a predator experiences what the signaller is warning them about they’ll generalise the experience to all individuals with the same colour/pattern

Question 28

Explain how an animal uses aposematic colouration to avoid predation

Answer 28

In some animals with aposematic colouration the predator will just see the aposematic colouration and avoid it or the signaller can send out the signal without getting hurt
However in other species the predator will only know to avoid animals with that aposematic colouration after experiencing what the colouration is supposed to warn them about
This means that this signal does not always help the individual animal facing the predator to survive

Question 29

How did aposematic colouration evolve?

Answer 29

Researchers wondered how aposematic species evolved when the first individual with the colouration would’ve been killed
Researchers noticed that aposematic species tend to be r-selected
R-selected species produce lots of offspring at once
This means that the predator only needs to kill 1 of the individuals to experience what the warning is for
After experiencing what the colours is warning about the predator would leave the killed individuals relatives alone
The relatives would have the same genes as the killed individual and therefore can survive to reproduce to pass on the aposematic genes to the next generation

Kin selection is often the answer

Question 30

What situations allow honest signalling to occur?

Answer 30

When the signaller and receiver’s interests coincide signals are honest

The signaller and receiver both want the same thing and so there’s no need to lie

Question 31

What situations cause signal dishonesty?

Answer 31

When the signaller and receiver’s interests conflict that is when dishonesty can pay off for the signaller

Question 32

Give examples of signal dishonesty

Answer 32

Predator-prey interactions
Pretending to be aposematic
Pretending to be harder to catch
Pretending they aren’t there through camouflage

Male-male conflict
Males should pretend to be stronger than they are

Make-female mate choice
Mates should pretend to be fitter than they are

Question 33

What 3 things keep signals honest?

Answer 33

1) Receivers evolve to rely on signals that cannot be faked
2) Signals are kept honest because those signals tend to be costly to produce

3) The most honest signals causally link with the feature of interest and are known as index signals
Index signal = a signal that correlates with the feature of interest
Honest signals are usually causally linked with things that they’re supposed to be signalling about

Question 34

Give some examples of dishonest signals

Answer 34

Camouflage
Confusing colouration
Mimic of aposematic species
Mimic of eggs
Predator distraction

Question 35

What happens when there’s a dishonest signal?

Answer 35

Whenever there’s a dishonest signal being used there’s an evolutionary arms race

Question 36

When there’s a evolutionary arms race what does natural selection favour?

Answer 36

In terms of animals, an evolutionary arms race is seen in cases of dishonest signalling leading to natural selection favouring:

     - Signallers who can produce the cheapest most convincing signal
     - Receivers who can distinguish real from fake

Question 37

What happens due to the natural selection of dishonest signals?

Answer 37

Due to the natural selection of signals, signals can evolve relatively fast compared to other features of biology
The signals will also change and become more and more elaborate over time

Question 38

What 3 circumstances can dishonest signals exist despite the receivers becoming really good at weeding the imposter out?

Answer 38

1) The dishonest signal is relatively rare compared to the honest signal
2) There is a high cost to a receiver who ignores a real signal
3) There is little cost to a receiver who believes a fake signal

Question 39

What does Harper 1991 believe receivers should believe and respond to a signal?

Answer 39

The proportion of fakes is less than the benefit of responding to a real signal relative to the cost of responding to a fake signal

Question 40

What is Harper 1991’s formula for the receiver to believe and respond to a signal?

Answer 40

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