Lecture 8: Communication Flashcards
communication is
transfer of information from a signaller to a receiver
communication can use..
CUES (not adapted) e.g. body heat + pheromones to attract mosquitos
or SIGNALS (adapted)
e.g. peacocks visual display
signals can use one of 5 sensory modalities
1) Visual
2) Acoustic
3) Chemical
4) Mechanical
5) Electrical
communication uses one sensory modality at any one time. T/F
Communication may use multiple sensory modalities to convey a message e.g. chicks in a nest begging for food
what four process’ may affect how signals evolve?
1) Evolutionary history and constraint – what is the animal capable of doing? What pre-existing behaviours can be adapted to produce signals?
2) Ecological context – what signals are appropriate?
3) Sensory bias – are receivers more responsive to a certain kind of signal?
4) Costs and benefits – like any other adaptation.
Evolutionary history and constraint affect on signal evolution: IN GANNETS
similarities between behaviours suggest that courtship displays evolved from pre-flight ‘intention movements’
Evolutionary history and constraint affect on signal evolution: IN PELECANIFORMES
species in this order have more similar courtship postures when they are more closely related. This suggests there is constraint to the evolution of this behaviour.
Ecological context affect on signal evolution
The environment broadly determines which types of signal are appropriate, e.g. visual signals not appropriate in total darkness.
It also exerts fine-scale selection on the ‘design’ of signals, e.g. the structure of birdsong in rural and urban environments.
Sensory bias affect on signal evolution
Signals may evolve because they are favoured by a pre-existing bias in the receiver.
Sensory bias affect on signal evolution: Fiddler crab
John Christy – female fiddler crabs of both species are attracted to the ‘hood’ structures built by male U. musica. In fact, they are attracted to any prominent structure (also wood, stones, shells).
Suggests female fiddler crabs may have a pre-existing sensory bias that makes them attracted to hoods. This would then drive the evolution of hood building in males.
(USED BY FEMALES AS PROTECTION, BUT MALES AS COURTSHIP)
Where do sensory biases come from?
- Random drift?
- Interest in a novel, obvious and prominent behaviour?
- Or an adaptive basis?
- –>Evidence – female fiddler crabs are attracted to hoods even when they aren’t sexually receptive. The hoods provide them protection from predators.
Cost & benefit affect on signals evolution
common trade off is being attractive to sexual partners and being visible to predators. e.g. Guppies
signaller and receiver generally have the same….however can be …
BROAD INTERESTS.
Example 1: male displaying to female – both individuals aiming to find a mate.
Example 2: chicks begging for food from parents, who are aiming to feed them.
However, there is often conflict in the communication process.
Example 1: optimal for male if female mates with him, optimal for female to mate with best male possible.
Example 2: optimal for each chick to demand more food than its siblings, optimal for parents to feed them equally.
3 points to do with conflict between signaller & receiver
1) coevolutionary arms races
2) stable honesty
3) understanding deception
coevolutionary arms races between signaller and receiver
MANIPULATION BY SIGNALLER: receiver is deceived into behaving in a way that benefits signaller –> RESISTANCE FROM RECEIVER: receiver ignores the deceptive signal –>
