Communication (L9) T2

Question 1

Two components required for communication

Answer 1

A signaler and a receiver. The behavior of a receiver is modified in response to the signaler.

Question 2

What info is contained in animal signals?

Answer 2

Information about either the signaler or the environment.

Question 3

INTRAspecific comm

Answer 3

1. Recognition of individuals
2. Reveal social status or aggressive intent.
3. Coordinate group spacing.
4. Locate food
5. Warn of danger
6. courtship and reproduction
7. Solicit or give attention such as play or parental care.

Question 4

INTERspecific comm

Answer 4

1. Recognition of species.
2. reveal aggressive intent.
3. Coordinate group spacing.
4. Locate food.
5. Warn of danger
6. Advertise unprofitability to potential predators.
7. Exploit supernormal stimuli

Question 5

How can an animal be preadapted for sending signals?

Answer 5

Ordinary, everyday activities provide potential information which may be modified or exaggerated as signals.

e.g. urination and defecation produce materials that happen to contain visual or olfactory information.

Question 6

How can conflict behaviors evolve into signals?

Answer 6

A conflict between two behavior may be redirected and modified into signals.

Aggressive behaviors may be redirected and eventually become stereotyped signals.

Question 7

Sensory exploitation hypothesis

Answer 7

A mutant signal becomes established in a population because it enables a signaler to exploit an already evolved preference or bias for that signal in a receiver.

Question 8

Discrete Signal

Answer 8

Either an entire signal or none at all is transmitted. Useful in POOR signaling conditions, such as at night.

e.g. Flashes of fireflies communicated between males and females

Question 9

Graded Signal

Answer 9

Varies in intensity as a function of the strength of the stimulus. Useful in good signaling conditions, such as during daylight.

e.g. threat of aggression communicated between rival male Moose.

Question 10

Benefits vs. Costs of signaling

Answer 10

Signaling should not appear in a population unless its benefits exceed its costs.

Signals that fail to generate a net benefit for a signaler will be eliminated by natural selection.

Question 11

What is the handicap principle?

Answer 11

A signal costs more to produce than could be gained by a fake signal.

Assures the receiver that the signaler is giving an honest signal.

e.g. Threats between two rival male wolves reliably indicate the sender’s motivation to follow through.

Question 12

Major benefits of signaling

Answer 12

1. Attracting a mate

2. Defending resources

Question 13

Major costs of signaling

Answer 13

1. Attracting predators, who are illegitimate receivers.

2. Possibility that species-specific code will be broken and mimicked by predators.

Question 14

Cooperative signaling

Answer 14

Both the signaler and receiver benefit. Signals are honest and often occur during foraging, courtship, and mating.

MOST common form of signaling.

Question 15

Deceitful signaling

Answer 15

Signaler benefits by deceiving the receiver. It is fairly common, especially in predator–prey interactions. It is more common between individuals of DIFFERENT species.

Question 16

Spiteful signaling

Answer 16

Neither the signaler nor the receiver benefits. This is common among humans, but rare among animals.

ex: Father killing wife and children.

Question 17

Incidental signaling

Answer 17

Signaler harms itself by unintentionally transferring information to receiver who benefits. Fairly common in predator-prey interactions and is the most common cause of predation.

Question 18

Chemical signals

Answer 18

The simplest communication system. Often used to detect prey/predator. Also used to attract a mate.

Question 19

Visual Signals

Answer 19

MOST COMMON form of signaling. Many species communicate with species-specific coded signals (e.g. signal-generating oscillator of fireflies.)

Question 20

Why do most nocturnal predators find fireflies distasteful?

Answer 20

They contain cardiac glyscosides which are self manufactured (not from food). Fireflies advertise their toxicity by glowing during larval stage and by flashing even when not courting.

Question 21

Firefly Courtship

Answer 21

Females wait on ground or in bushes until, seeing the right signal, they respond with an appropriate answer–often just a simple flash.

The temporal pattern of male’s signal is important. Timing between male’s signal and female’s signal is important.

Male uses female’s coded signal to zero in until they are close enough to land and mate. Possible to crack the code by using a pen light, upon which males will actually land.

Question 22

What is unique about a few species with several pulse-code circuits?

Answer 22

Female seduces males of other species by using their flash code, then captures and eats them.

Question 23

Auditory Signals

Answer 23

Some species will use these signals more so than visual signals (e.g. water striders communicate to females and listen through their legs on the water’s surface).

Sound travels faster than chemicals. Nocturnal species especially tend to communicate with auditory signals.

Question 24

Crickets auditory signaling

Answer 24

Male crickets broadcast an invitation song and receptive females move toward source. Once they are nearby the male switches to a courtship song and if it goes well then they mate.

Rate at which crickets sing (and walk and breathe) increases with temp. Females responds only to songs produced at the rate which is appropriate for her body temperature.

Female’s filter (IRM) has the same temperature-dependent characteristics as the male’s oscillator circuits.

Question 25

What features of cricket songs are females most receptive to?

Answer 25

Interval of mills, intervals between chirps and intervals between trills.

HOWEVER: when the pattern is scrambled but the same intervals are maintained, there is no effect on the females.

Question 26

Why is the presence of both singing males and silent satellite males an evolutionarily stable strategy?

Answer 26

If there are too many silent satellite males, the singing males face an advantage.

If there are too many singing males, the silent satellite males will have an advantage.

Question 27

Electric Signals

Answer 27

Weakly electric fish use electric pulses to “see” in the dark and to communicate. Males and females have different pulses and pulse-repetition rates.

During breeding season, unmated males respond to female signals with a special electrical courtship “rasp” signal.