Tuesday 14th August 2018 - Animal Communication Flashcards
Review of Key Concepts
1. Define communication?
2. Who are the beneficiaries?
- When an animal (sender) transmits a signal to another animal (receiver).
- Either Senders or receivers can benefit from the process.
1. Define ‘signals’?
2. Which organ perceives them?
3. Once In__________, re________ may follow.
‘Stimuli that convey specific information’
- Perceived via sensory organs.
(Odour picked up by olfactory systems)
-Interpreted, responses may follow.
Signals can be one of two things, what are they? give two examples of each kind.
1. Behaviours
- Vocalisations, postures, etc.
2. permanent ornaments.
- E.g., colourations, feathers.
Not all behaviours intentionally convey information.
Give three examples of this.
- Rabbit sneezing and giving away its location to a predatory is not conveying information, it is just bad luck.
- Grey hair is a signal of being older, not an intentional communicative signal.
- Sweat, a signal of a hot animal.
Channels of communication - pros/cons
1. Name the 5 ‘Signal Types’ and the factos which affect their effectiveness.
2. Name the two constraints that impact communication
1. Signal Types
Visual
Auditory
Chemical
Electrical
Tactile
1. Factors affecting
Visual: Depends on environment. Light availability impacts signal visability and percievability of reciever. Visual symptons communicate location of sender which could be an advantage to attract mates but a disadvantage if there is a predator eves dropping. Heavy vegetation and objects obstructs ethicacy. Can be rapid form of communication in light open environment.
2. Constraints
Biological constraints
Habitat constraints
What signals are being produced here?
Visual
Posture change
Teeth
Change in muscles around face
Raised tail
Lower tail
Auditory
Growling
Odour?
Dog on heat?
Visual vs chemical
What are the pros and cons of each?
Visual pros
- Picked up by all visual species
- Really fast method of communication between signaller and receiver
- Little energy use to produce signal?
Visual cons
- Limited by not being able to see it (receiver looking away or barrier in the way)
Chemical Pros
- Chemical signals linger longer in the environment depending on chemical composure
Chemical Cons
- Can be washed away by weather or over marked by other animals peeing on it etc
What is the difference between ‘Discrete’ and ‘Graded’ signal?
Discrete
- Contact call (all or nothing)
(short sharp, cleary defined start and clearly defined end)
- Fireflies
(Flash on or off, clear start and clear end)
Graded
Levels of intensity
(cat ears going from upright to normal)
E.g., posture
E.g., growling
E.g., facial expression
Study cat diagram below
What communications are involved in Albatros courtship?
1. Auditory (Squaking)
2. Tactile (Beak touching)
3. Visual (beaks gawping & head bobbing)
1. What are Composite/multi-modal signals?
2. Describe both Redundant transmitting & Non-redundant transmitting
1. Vocalisation and gestures describing/communicating the same information
(Two modes, same info)
2.
Redundant
(Transmitting same info)
(Noisy bar - Man describing ‘massive fish’ vocally and gesturing with hands to indicate size)
Non-redundant
(Transmitting different info)
(Chick begging behaviour)
- Postural display
Intensity associated with need (intense movements when hungry).
But - larger nestlings can be more vigorous
- Vocalisations
Aspects of vocalistions better correlated with hunger in some spp.
- Colour
Related to to body condition/immunocompetence - parents may preferentially feed (Brighter colours in a chick may lead to them being fed better by mother as more likely to survive).
Honesty in communication
1. Are all signals ‘honest’ and Is deception common?
2. What is Reliability?
1. Senders and receivers don’t always have the same goals
2. Reliability
Average likelihood that a signal will allow a receiver to gain accurate information about a situation/state/event.
- It may be to the signaller’s benefit to bluff.
- E.g., how willing they are to defend/gain a resource.
- E.g., how good a potential mate they are.
Note
Senders and receivers aren’t perfect - errors can be made.
Honesty in communication
There should be overall (net) benefits for both senders and receivers to even bother producing signals, and receivers bother attending to them.
(Why would senders even bother producing signals that require alot of energy and perhaps risk if they weren’t beneficial overall)
Because there are also costs incurred during communication.
- E.g., energy, time, conspicuousness/predation risk.
Honesty in Communication
Honest signals are likely when what?
(Four things)
- Overlapping goals
- Handicap signals
- Index signals
- Dishonest signallers can be identified
Honesty in communication
Give an example of an ‘overlapping goal’.
When goals are the same, honest signalling is advantageous to both.
- E.g., forager-sender bees signalling to worker-receivers.
- (Go out to find food and they signal to conspecifics where else to find food. Common goal is to provision nest mates so why would they be dishonest about location of food)*
E.g., parents-offspring
Begging chicks - intensity (graded) correlated with hunger.
- Parents’ fitness linked to offspring’s survival.
(Common goal is chick wants to survive and mother wants chick to survive)
- Begging noises makes them conspicuous to predatos - so it is costly when not necessary.
Dishonesty may arise if goals conflict
- E.g., if chick tries to get more than siblings/parent is willing to give.
Honesty in Communication
Handicap signals are expensive to produce! (Handicap principle).
Reliability is maintained due to production costs.
- Theoretically, all senders may produce/develop the same signals; however handicaps enforce honesty via imposing costs that reveal properties of senders (e.g., more/less vigour).
- Senders vary in their ability to bear those costs.
Poorer-quality individuals = Less intense variants of signals
(Unhealthy animals send weaker signals)
E.g., common in courtship
(Healthier stronger males attract females better)
E.g., Signalling to predators about escape ability.
(When an animal sees a predator it may stop and jump (event) up and down which communicates to the predator it is very fit and can run very fast so the predator may not bother wasting the energy to chase it if it wants an easier kill/meal)
Honest in Communication
Handicap signals examples
Explain how this relates to ‘Barn Swallows’
Aerial foragers, longer tails more drag which is a handicap in the foraging sense but females prefer longer tails which is a benefit from a mating perspective.
- Females prefer males with long tails
- Aerial foragers - longer tails impede foraging
- Longer tails associated with
stronger,
healthier,
parasite-resistant.
Push up displays in side blotched lizard also energetically expensive (measure of endurance)
Honesty in Communication?
What are ‘Index Signals’ ?
Index signals cannot be faked
They are honest signals of things such as body size.
(Can change posture or puff feathers to make themselves look bigger)
Only some senders can produce certain signals because of their size.
- Different to handicap signals, where all senders could potentially produce/develop the signals, but the cost of signal production reveals information about them.
- index signals are when choice of signal production is limited. The senders are constrained physiologically.
(If you are small, you cannot make as bigger roar as the bigger conspecific)
- It is not the cost that ensures honesty with indices
Example of Index signal
Reaching high up the tree and scratching which leaves a visual cue of the height it can reach (aka its size). Olfactory cues also left from scent glands in the pad. Smaller tigers simply cannot reach and scratch that high.
if animals are living in a stable social group where they can learn information about members of that group, they will be able to identify when an animal is giving false or dishonest information on a regular bases. Which is why it is thought animal signalling is ‘honest’ with their social signalling.
Dishonesty in communication
When might we see dishonesty?
- Deceit may be possible if assessing a signal is expensive.
E.g., increased predation risk of assessing a signal
- If signals are expensive to challenge, receivers may be unwilling to test them > deception.
E.g., newly-molted mantis shrimp’s ‘meral spread’ display,
When shrimps have molted they are less able to engage in territorial defences behaviours. What they do is extend the appendage and use for predation and territorial defence which can cause serious injury or death. One thing they do before they attack is a ‘meral spread’ which is the first part of the signal it is going to attack.
When freshly-molted they are unable to attack as they are to soft.
They may ‘bluff’ regardless.
- Likelihood of retaining burrow when challenged by a intruder is higher if they bluff. If they do nothing they are likely to be kicked out, but if they bluff the intruder is likely to back off.
Dishonesty in communication
Give an example of ‘Illegitimate receivers’
‘A Hi-jacking/interception’
Illegitimate receivers’ use information transmitted (not to them), to the detriment of legitimate senders/receivers.
E.g., Predators using prey’s calls.
E.g., Tungara frogs - mate-calling at night, predated upon by bats.
- Part of their ‘whine chuck’ call (‘chuck’) is attrictive to females… and BATS!
- *- Trade off between mate attraction and survival.**
Experiments found bats twice as likely to attend to speakers with all call components vs. chuck-less calls.
We would expect more complex calls when lower predation risk.
Males in groups use whine-chuck calls - dilution effect
(safety in numbers like mammals herding together)
Given an example of ‘Illegitimate senders’
Produce signals that reduce fitness of receivers.
- E.g., mimic other animals’ signals (Spider generating moth sex pheromone)
- E.g., ‘Femmes fatales’ female ‘Photuris fireflies’ can mimic signals of 3 spp.
- Answer males of other spp. using species - appropriate flash signals, luring them in. Grab and eat.
- But thought on average, male receivers’ responses increase fitness - this response to female flashing persists.
Honesty in communication
Overall…. most signals are considered honest due to the costs involved.
If dishonesty was rife, signals wouldn’t benefit anyone.
- Receivers would stop responding
- On average, receivers should benefit from signals (senders too).
How did signals evolve?
Explain the following:
- Intention movements.
- Displacement movements
- Autonomic responses
Intention movements
- Animals start behaviour patterns in typical ways, these become ritualised (only that first part is retained)
- Aggression - costly to complete entire pattern, benefits to interpreting
(Why esculate right through to true aggression when you can display one part of that sequence and get the desired result)
First signal and act accordingly.
- Displacement movements
- Behaviours that are contact - innapropriate
- E.g., grooming the face of aggression
- Hypothesised as a response to conflicting motivations
(i. e., fight/flight/fright) - Difficult to determine function of some responses.
E.g., mock preening in courtship displays of ducks.
- Autonomic responses
E.g., vasodilation related to stress - courtship and agonistic displays include reddening and swelling of head/skin flesh in some bird species.
How did signals evolve?
A receiver bias may influence evolution of signals.
Receivers may have a perceptual bias for particlaur signals - sensory exploitation hypotheis
E.g., Their sensory system may be more receptive to particular signals, such as frequencies, colours, forms.
- Males who can take advantage of females’ biases will be more successful.
- This can influence evolution of signals.
E.g., male water mites’ courtship signals mimic prey vibrations.
How did signals evolve?
Signals may also evolve under environmental constraints.
E.g., vegetation influences acoustic signals’ attenuation - thus influences most-common frequencies.
E.g., some Lizard species can signal more rapidly in noisier environments - increasing their conspicuousness.
