Communication Flashcards
Difference between discrete and graded signals?
Discrete - operate in an on/off manner
- convey only single, simple messages
- eg. flashing signals of fireflies
Graded signals - varying intensity and complexity
- often costly in time, energy and risk
- eg. ants produce alarm substance in proportion to the stimulus
What are the channels of communication?
Visual Acoustic Electrical Chemical Mechanical
What is visual communication?
Information transmitted by visual means - movement, posture, facial expressions, colour identification
Generally used during the day though light used at night
Advantage - can be altered quickly to allow rapid changes in the message
Disadvantage - messages easily blocked by obstructions like thick vegetation
Give an example of visual communication
Karl Von Frisch 1965 - Worker bees
Worker bees communicate about food via a dance language
Discovered bees perform 2 types of dance
- round dance indicates food is 100m away but will communicate both distance and direction
What is acoustic communication?
Sending information via sound - called bioacoustics signaling
Good means of communicating over long distances in both air and water
Can be produced via vocal organ or other body parts
Advantage - can have a good range of detection
Disadvantage - risky and instantaneous - no longevity
What is electrical communication?
Species use patterns of electrical discharges such as intervals between pulses
Only used in aquatic species
Often used in murky conditions
Communicates information about species identity, sex, dominance relationships
What is chemical communication?
Molecules used for chemical communication between individual animals = pheromones
Involved in mate identification, marking territories and alarm spreading
Advantages - can transmit info in the light and dark
- travel long distances
- may persist for long periods of time
Disadvantages - often costly
- requires diffusion of signal
- may not persist for long periods of time
What is mechanical communication?
Signals transmitted through tactile cues and/or substrate-borne vibrations
Only effective at extremely short range
Signals degrade as they are transmitted and may well be masked
Extensively used by a wide range of invertebrates - cannibalistic spiders (Portia spider)
Possible use by elephants
Give examples of how different ants use signals to different effect
Harvester ants - feed on single immobile prey, if too heavy for one worker regurgitates food at nest and recruits help leading them to the food via tandem running
Fire ants - feed on large mobile prey, worker recruits prey and returns to nest depositing scent trail, workers attracted and reinforce scent trail until food is gone then trail is not used and chemicals dissipate
Leaf-cutter ants - Eat stable food sources and so use the same paths for long periods of times, they use long lasting odours
What 2 fundamental problems to acoustic signals in particular suffer from?
Attenuation - reduction in amplitude of a signal due to sound waves being absorbed by air or colliding with vegetation and other obstacles
Degradation - Distortion of a sound signal through other noises such as echoes, gusts of wind etc
How did signals originate?
Heavily influenced by the environment in which the signal is broadcast
Ancestry - likely that non-signalling activity existed before the signal and signal was derived from it by gradual modification via evolution
Three particular classes of activities identified as most common source
- intention movements
- displacement activities
- autonomic nervous system activities
What are intentional movements?
Activities that tend to precede some other activity
eg humans looking towards door when you wish to leave a room
What are displacement activites?
Actions that appear irrelevant to the circumstances and performed at times of motivational conflict
eg humans presented with two options but not sure what to do so scratches head
eg ducks seeing a conspecific may be inclined to approach it (for courtship) but also to flee - instead preens its feathers
What are autonomic nervous activities?
System of nerves that are separate from but connected to the central nervous system
- controls much of the unconscious activities of our body: aroual, rapid breathing, sweating
Causes some mammals to urinate at times of fear
Evolved into territorial signal as an individual shouldn’t be fearful when inside its own territory
What is ritualisation?
The evolutionary process by which signals become stereotyped
eg teeth baring in wolves
Reduces ambiguity of signals
Benefit in that one signal becomes clearly distinguishable from another
Reduces risk of confusing reciever
eg attack signal won’t be confused with fear
