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Chapter 5

Chapter 5 study guide

Course Code
Robert Gerlai

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Ch. 5 Communication
Key Points
-in the context of animal behavior communication is the sharing of information between
-exactly how communication is transferred will depend upon the machinery available to the
individual, upon the environment through which the transfer will take place, and upon the
evolutionary history of the animals involved
-although there will be occasions when communicating individuals share information in
good faith, there will also be occasions when they attempt to deceive on another
What is communication?
-So what is shared when animals communicate? Information. When they communicate they
transmit and receive signals, units of information
A Question of Intent
-The word intent in the sense of a voluntary action (voluntary intent).
-evolutionary intent: the execution of a behavior that the individual does not choose to
exhibit, but which is performed as a result of natural selection (may also be referred to as
involuntary intent)
- Ex. As you walk past someone you dont like, you dont wave to them but you
involuntarily flick your eyebrows up.
-Involuntary communication of intent (?)
-Ex. When your brake while driving your letting the drivers behind you know your
stopping or slowing even though your intent is to stop or slow down.
Communication without signals?
- Animals do gain info through the observation of other behaviors that are performed by
animals but which have not evolved for this purpose (ex. Utilize cues)
-example: a pigeon that sees a flock of other pigeons feeding in a field might gain info
about the suitability of the field as a feeding site and join them. It did not however gain this

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information as a result of communication between itself and the members of the flock
Honesty and Dishonesty
-examples: when u brake the red light comes up and informs of braking (honest)
-examples: when u flash your signal its only honest if you actually turn that way after the
signal but it will be dishonest if you dont end up turning
Ants and snakes
- ants lay down a pheromone trail to let other ants to know where to go home or to food
-snakes that prey on ants can pick up on this scent
-key point the ants dont mean to tell the snakes where they are
The evolution and design of signals
-some animals use sound, chemicals, touch, vibration, visual signals, and/or body postures
Selective pressures and the evolution of signals.
-Selective pressures that operate during evolution of a signal
- Not all signal types will stimulate the sensory systems of the receiver to the same
-the environment though which signaling is to occur will strongly influence the
design of a signal–after all not all signal types will travel from sender to receiver with equal
- The interests of the signaler and receiver will not always coincide, selective
pressures might favor the a dishonest signal on the part of a sender, but similar pressures
acting on the standpoint of the receiver might favor honesty
Frog semaphore
- Precisely the methods of communications that are used by one species will depend in a
large part upon the environment in which they communicate but the method must also
depend to an extent upon the equipment available to the individual.
-Most species of frog and toad croak at one another as a form of social communication
-However one species, the Panamanian golden frog lacks an essential component of the
machinery required for acoustic communication (has no tympanic middle ear. Otherwise its

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-The golden frogs do respond to sound so otherwise its not completely deaf but the
sensitivity to sound is too high to use sounds as means of communication
-During their evolutionary development an alternative mode of communication has arisen
(one that makes use of machinery that is already available to them)
-A well developed visual system led to the development of a visual communication system
-They communicate using a system of semaphore
-Individuals wave at one another, and although the exact message that they transmit
remain elusive to us, they are thought to relate to territorial defense and sexual selection
the same function that have been attributed to the croaks of their cousin
Sensory preferences and signal detection
-Sensory exploitation: the theory that signals evolve to exploit pre-existing sensory
biases on the part of the receiver.
-ex. Some flower trick male insects into pollinating them than other by resembling
female insects. Not pollinated because the flowers are attractive but because of the existing
bias for them
Signal Evolution, Ritualization and Antithesis
-The evolution of a signal can be thought of as a process of having six basic steps
1. An association between a behavioral, physiological, or morphological cue and a
behavioral motivation/condition as an initial signal on the part of the sender
2. The perception of the cue on the part of the receiver
3. Relating of the cue to the motivation/condition of the sender by the receiver
4. The development of a decision rule by the receiver in response to it relating the
cue to the motivation/condition
5. The evolution of a response to the cue/signaling by the receiver
6. The process of ritualization refines the cue to create a true signal.
-Example exaggerated crouch with the tail fanned and lowered and the wings spread
communicate I am likely to attack:
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