The function or adaptive value of signals has been broken down into the following classes:

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1 Communication notes.doc 1 Communication and signals an action on the part of one animal that alters the behavior of another (Wilson 1975). The essence of communication is the relationship between signaler (sender) and receiver. What about a mouse rustling in the grass that an owl hears? Is it communicating? Some discrepancy over whether the sender must receive a benefit and/or intend to signal This has lead to further classification of signals. 1) True communication both sender and receiver benefit 2) Manipulation or deceit sender benefits, receiver is unaffected or harmed 3) Exploitation or eavesdropping sender is unaffected or harmed, receiver benefits 4) Ignoring or spite neither sender or receiver benefits, both may be harmed While the benefits to the signaler are fairly intuitive, the benefits to the receiver can be intended or unintended. Communication with an intended receiver usually will be mutually beneficial. However, they may be many unintended receivers intercepting the signals. Animal communication is typically thought of as being adaptive. Why else should an individual (signaler) communicate unless they are going to receive some benefit from their actions. The benefits for the signaler have already been outlined for the signals of sexual selection. The function or adaptive value of signals has been broken down into the following classes: 1. Recognition of species, individuals, neighbors, castes (social insects), kin, or demes; need to recognize mates, classes, groups, or relatives 2. Reproduction which involves courtship by males, female choice, or female receptivity (e.g, acceptance or rejection); Courtship stimulus-response chain the behavior of one individual in turn releases a behavior of another individual 3. Agonistic interactions and the establishment of social status;

2 Communication notes.doc 2 competition and fighting, convey status or dominance relationships without continual fighting 4. Alarm calls among group dwelling animals; 5. Coordination among hunting animals; or other food communication 6. Parental care -- parent offspring recognition and calls by offspring or actions to bring food. Different groups of animals rely on different modes of communication. Auditory, visual, Chemical, tactile Chemical odors and Pheromones chemical messangers used for communication hamsters recognize each other by smell, mate identification, spacing, Work at night, travels around obstacles, can last for a long time which can be good or bad Visual unlike chemicals, they travel very fast and are highly effective, can be directed, ineffective at night Auditory sound, travels far, goes around things, works at night and in water and air disadvantage indiscriminate; often used for locating others at a distance or alarm calls Tactile communicate with touch very personal, cannot be overheard but obviously must be close; very important for mammals, kissing and grooming in primates Many signals use a combination of things Signal types Specific vs. general Specific only have an effect on members of the same species particularly important in attraction and courtship waste of time for both individuals to

3 Communication notes.doc 3 be attracted to the wrong mate because of this courtship signals tend to be the most highly developed and specialized General Affects all animals, conspecifics and others, even predator Specific are more complex, complexity is required to make the signal unique. Why not always Specific? 1) You may want to reach multiple individuals 2) However there are costs to producing a more complex signal. Complex signals take more energy and may also take more time to broadcast than a simple one. As a result, complex signals tend to evolve only when there are strong advantages associated with the specificity. Discreet vs. graded Discreet- signal is either present or absent; on/off, these are usually things you want to be very clear, evolved for clarity sexual attractants, or identification like by birds, sounds that identify members of a flock. I am a particular type of bird and I am here. The evolutionary path for discreet signals is clarity. You want no chance of misinterpretation. Graded variable in strength usually vary in intensity in proportion to the strength of the stimulus convey information about the sender s motivation the higher the motivation the more intense or longer the signal Most likely to be used in interactions between two individuals male to male comp, alarm call or growling in dogs Mammals and birds are the most likely to use graded signals than cold blooded animals like insects.

4 Communication notes.doc 4 Amount of information conveyed Amount of information communicated between animals varies greatly between species. The flash of a firefly says I m here and I want to mate vs. the honeybee dance. It was originally thought that animals that conveyed more information had a larger variety of displays (signal or behavior pattern that are specialized to convey information) but that But most species have similar numbers of displays fish, green heron,elk=26, vervet monkey =37 but they convey different amounts of information There seems to be an upper limit to the ability of animals to process signal diversity. So how do they convey additional information? Enrichment devices signals that modify the meaning of another signal 1) Medley composite signal two or more signals are presented together they mean something different than the two presented alone 2) Syntax information provided by the sequence of displays not present naturally in non-humans (chimps can do it who have been taught sign language) A followed by B means something diff. than B followed by A 3) Metacommunication communication about the meaning of communication; play face in a chimp or the stretching out of forepaws in a dog to play the dog implies that the aggressive behavior to follow is not meant as a challenge 4) Regulate intensity or duration a loud or long dog bark means something different than a short soft one 5) Contextual effect the context in which a message is given can enrich the message Ex. Male displays, aggressive toward other males but express sexual intentions toward females

5 Communication notes.doc 5 Ex. Lion s roar has 4 potontial meanings depending on context 1) attractiveness for pride members 2) a spacing device for neighbors 3) a threat during aggressive encounters 4) way of locating members of the pride during separation Same message also interpreted different, depending on the receiver On the other end of Enrichment devices which expand the ability to communicate large amounts of information is Redundancy saying the same thing over and over may be accomplished by repeating a signal or by the presentation of multiple signals with the same meaning. Because signaling has a cost it is fair to ask What is the Function of Redundancy? And if you have ever been awakened by a crow or a dog barking you may wonder why does redundancy happen to such an extreme. 1) reduce risk of misinterpretation - redundancy reduces the chance that a signal will be missed or misinterpreted increases the chance the signal will be received correctly. Need can be great when reception is poor dim light or background noise or if the receiver is distracted. 2) Repeated communication may allow individuals the opportunity to reassess each other s situation when motivational states are important or likely to change Ex. Comp. You get tired or lose interest 3) Coordinate sexual arousal and maintain at a high level evidenced by courtship displays which are presented over and over 4) Increased memorability true only when there is simultaneous presentation of multiple signals that have the same meaning. Animal that is the most memorable may be the one chosen as a mate. i.e. redundant by giving different signals that mean the same thing not just repeating one. a. Ex. Male birds sing, dance, and dramatic colors Mode of communication can be limited by environment but also different modes may be selected for because of their specific properties.

6 Communication notes.doc 6 Fire ants use odour trails to guide the way to dead prey. Scent trail builds up but is short lived. This avoids individuals going there long after prey is gone. Other ants with renewable food resources have longer lasting cues. Different calls transmit better or differently in different environments. Often different call properties of species match the environment (comparative method). Can be conflict in best mode Distance short vs. long Degradation quality of signal Location difficult or easy to locate Origination of signal Intention movements some things always done before action dog bars teeth before biting Displacement activities inadvertent actions at times of stress or motivational conflict. Urination, blushing, hair on end Evolution of signals Often begin with intention movements actions that are always done before something happens a cat raising its paw These signals later evolve and become ritualized Ritualization the evolutionary modification of movements and structures to improve their signal design. The changes that come from ritualization include Movements tend to become highly stereotyped, repetitive, and exaggerated

7 Communication notes.doc 7 Often the movements can be emphasized by the development of bright colors in key areas. Move wings, bright color on tips Why ritualization 1) Reduction of ambiguity 2) Manipulation want others to do what you want, must turn up the volume 3) Honesty all receivers are under selective pressure to identify liars