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1Photo Copyright R. Hays Cummins CommunicationChapter 12Photo Copyright R. Hays Cummins
2Communication What is communication? How signals convey meaning Types (traits vs. behaviours), classificationHow signals convey meaningChannels of communication (methods)Functions of communication (purposes)Complex Communication (bee dance)
3Types of Communication What isCommunication?DefinitionTypes of CommunicationBehaviours (‘signals’)States/TraitsHow is Communication Classified?Categories ofInteraction (Wiley)Other views
4What Is Communication? In biology, defined as: The transfer of information from one molecule, cell, or organism to another, as by chemical or electrical signals or by behaviours. (www.dictionary.com)All communication involves a “sender” and a “receiver”
5Biological Communication Signal: The physical form in which a message is coded; any behaviour pattern that communicates somethingDiscrete vs. GradedDiscrete: “All or none” (e.g., FAPs)Graded: Varying in intensity and/or frequency; provides info about the strength of stimulus (e.g., Betta splendens display)
6Discrete signal (ear position) Graded signal (mouth)Increasing intensity
7Biological Communication Displays are one type of signalDisplay: Any behaviour pattern especially adapted (i.e., modified through evolution) in physical form or frequency to function as a social signal in communicatione.g., spruce grouse males beating wings on aire.g., male dominance mounting in dogs
8Two male Betta splendens showing fin flare and operculum (gill) flare Communicates willingness to fight; allows assessment of opponent without combat/injury
9Wiley (1983): Categories of Interactions Terms used to describe interactions, depending on the value of the info to sender and receiverValue of info to RECEIVERValue of info to SENDER:positivezero (negative)“True communication”“Manipulation” (“deceit”)“Eavesdropping” (“exploitation”)“Ignoring” (“spite”)+/++/0 +/-0/+-/+0/ /-
10Biological Communication How to classify/define communication?Value of information to each participantCost & Benefit AnalysisBoth benefit = true communication;male bird song during mating seasonSender benefits, receiver is unaffected or harmed = deceit or manipulation; e.g., killdeer performing “broken wing display”
11Biological Communication ® Disney, Finding NemoDeceitInterspecific deceit more commonpredator-prey relationshipsAquatic predators that attract prey using lures that look like insectsIntraspecific “deceit” unlikely to spread in a population, except…
12Categories of Interactions Sender benefits, receiver is harmed (+/-):DeceitAnother example:“femme fatale” fireflies – females pretend to be receptive, attract and consume males of another speciesSometimes the receiver is actually harmed. This is what Wiley labelled as deciet. For example, the female send out signals that attract the male to come and mate with her, then she eats him. The male dies, but could be said to benefit indirectly in that his genes are passed on, so this is a tricky one.Batesian mimicry can sometimes be considered deceit in that the predator wastes energy in initial pursuit of the prey, then retreats, such as a bird pursuing a caterpillar that then inflates its posterior to look like a snake and scares the bird away.
13Biological Communication Value of information to each? Cont’dSender unaffected or harmed, receiver benefits = exploitation or eavesdropping;mouse rustles grass as running, allowing owl to hear it, catch it & eat itNeither benefit, both may be harmed = ignoring or spite;a bird ignores the cryptic colouration of a moth and tries to eat itMonarch Butterfly
14Biological Communication Other ways to view communication:Communication need not benefit both sender and receiver since natural selection operates mainly at the level of the individual (Dawkins & Krebs);Displays evolve to “waste” a minimum of energy of sender… persuade the receiver, not “inform” (exaggeration and redundancy of signals);roar of male lion
15Biological Communication Other ways to view communication:Displays – have evolved to maximize the effectiveness of information transfer, to the benefit of both sender and receivercoevolution of signals; each species acts as a strong selection force on the other;Problem: this definition cannot encompass “lying”
16How Signals Convey Meaning Distance & Duration (signal type)Can travel far (e.g. scent), or operate over short distances (e.g., visual signals)Can be long-lasting (e.g., pheromones entire breeding season) vs. short-term (e.g., calls/ vocalizations)
17How Signals Convey Meaning Individuals can increase information content of signals by… combining 2+ signals = composite signalZebra: meaning of “open mouth” signal depends on ear position (forward = friendly; backwards = hostile)…changing syntax, or sequence of displaysA before B is NOT = B before A
18How Signals Convey Meaning Information in a signal can be context-dependent;E.g., “lion’s roar” : aggressive, maintaining contact with pride members, or indication to neighbours to keep a good distance
19Types of Communication (How can a message be sent?) States or Traits:Sign stimuli – Ch.’s 2 & 10Aposematism & Batesian mimicry – Ch. 15Indicator traits – Ch. 17 (to come)Behaviours: (i.e., “does”)SignalsSome FAPsDisplaysCommunication can be broken down into different types. This isn’t quite clear from your textbook, but I find it helpful to think of types of communication in terms of whether they are a “state” or trait, or a behaviour. For the states/traits, some of these you have encountered in earlier chapters.
20Sign Stimuli Three-spined stickleback (Ch. 2, p. 15) Enlarged belly of female = Sign stimulus (honest sign that female is ready to spawn)
21Sign Stimuli Not a behaviour, a state (e.g., enlarged belly) May provide info about physical state of bearerNOTE: Not all sign stimuli convey information, and not all FAPs act as signalsE.g., egg retrieval in gullsIf info is exchanged between conspecifics when sign stimulus or FAP occurs = communication
22Aposematism (warning colouration) Conspicuous markings of noxious animals are easily recognizable and avoidable by predatorsConvey information about unpalatabilityBatesian mimicry = manipulation/deceit (lying)Aposematism is another example of a type of communication that involves a state or trait. In this case, the warning colouration or marking of a species communicates to predators that it is unpalatable or toxic.Batesian mimicry is also a type of communication, however, rahte than being an honest signal of unpalatability, it is in effect lying or deceiving as predator into believing that the prey is toxic.pinker.wjh.harvard.edu/ photos/santa_barbara_c...
23Communication What is communication? How signals convey meaning Types (traits vs. behaviours), classificationHow signals convey meaningChannels of communication (methods)Functions of communication (purposes)Complex Communication (bee dance)
24Channels of Communication OdourSound (ultrasonic, sonic, and infrasonic)Seismic vibrationsTouchElectric fieldVisualThe physical form used to transmit the signal from sender to receiver. The form in which a message is transmitted.Think “method of transmission” or “modality”
25Properties of Sensory Channels Range (distance covered) – short to longTransmission rate (how long does it take to get from sender to receiver?) – slow to fastCan it travel around objects? – yes or noCan it be used at night? (yes, no, or sometimes)Fade-out time (how long does it last? – slow to fast)Locate sender? (easy to difficult)Cost to send signal (low to high)Complexity of message (low to high)When comparing the usefulness of 2 different channels, these properties are thing to consider. These are just some things you want to consdier when compareing the various sensory channels.
26Audition: Properties Auditory communication Range? longTravels around objects?YesUseful at night?Fade-out time?FastCost to sender?High
27Odour Used by most species (evolutionarily “old”) Usually involves pheromones:a species-specific odour cue released by animals that influences the behaviour and/or physiology of conspecificsPriming pheromones produce a generalized response such as triggering estrogen and progesterone production that leads to estrus, while signaling pheromones produce an immediate motor response, such as the initiation of a mounting sequence.
28Odour Functions: Group spacing – marking territories Recognition – identifying conspecifics, kin, individualsReproduction – attracting mates, altering physiology (e.g., levels of sex hormones)Alarm – fear pheromone (e.g., inverts)
29Odour Pheromones often present in urine of mammals (& anal glands) Two types:priming (generalized response)signaling (immediate specific response)“Flehmen” response (vomeronasal organ)Territories = group spacingMate attraction = reproduction, also ovulation receptiveness, etc.
30Odour: Properties long range slow transmission rate travels around objectsuseful at nightslow fade-out timelow cost to senderunable to locate sendersimple message only(unless within a territory)
31Sound Can occur within or outside of human “umwelt” (~20-20,000 Hz) ultrasonic (high frequency - e.g., echolocation)infrasonic (low frequency - e.g., African elephant rumbles, whale song)
32Sound Can be produced by: stridulation (e.g., cricket “chirp”) a single organ (vocalizations)stridulation (e.g., cricket “chirp”)other means (e.g., drumming by Northern Flickers/ woodpeckers)
33Seismic Vibration Substrate-borne vibrations detected by animals White-lipped male frogs make thumps, females extremely sensitive to vibrationsSpiders catch prey by detecting vibrationsMale orb-weaving spiders “pluck” at web to bring female out for mating
34Sound/Vibration Properties long rangefast transmission ratetravels around objectsuseful at nightfast fade-out timehigh cost to sendermay be able to locate sendersound = complex message, vibration = simple message
35Touch Tactile communication (physical contact) Common in invertebrates: Antennae, tube feet, etc. (also pick up chemical cues)Vertebrate copulation tactile stimulation elicits lordosis response in female mammalsTouch (e.g., vaginal stimulation) can induce ovulation in some species (induced ovulators)
36Touch: Properties short range fast transmission rate can’t travel around objectsuseful at nightfast fade-out timelow cost to sendereasy to locate senderSimple message only
37Visual Communication Markings, patterns, colour require vision Mostly used by diurnal species (visual displays), e.g., aggressive displays of SFFException: firefliesspecies-specific flashing to attract mates and during courtship“femme fatales” of Photuris versicolor (deceit)
38Vision: Properties medium range fast transmission rate can’t travel around objectslittle use at nightfast fade-out timecost to sender mediumeasy to locate senderallows complex messages
39WhoZoo(http://whozoo.org)Electric FieldSome sharks and electric fish detect prey’s electric field using electroreceptorsStrongly electric fish (e.g., electric eel) have EODs (electric organ discharges of 100’s V)Social communication possible by altering wavelength/ pulse duration
40Electric Field: Properties short rangefast transmission ratetravels around (and through) objectsuseful at night/in murky waterfast fade-out timecost to sender varieseasy to locate senderSimple message only
41Functions of Communication Group spacing & coordinationRecognitionReproduction (identifying/attracting mates)Agonism and social statusAlarm (warning)Finding foodSoliciting playGiving & soliciting careSynchronization of hatching
42Functions of Communication Group Spacing & CoordinationSpacing signals of primates:Distance-increasing (branch shaking)Distance-maintaining (dawn chorus)Distance-reducing (contact/lost calls)Proximity-maintaining (social grooming)
43Functions of Communication RecognitionSpecies RecognitionNeighbour RecognitionIndividual RecognitionKin Recognition
44Functions of Communication ReproductionCourting displays, copulation- allow assessments of species, physical condition, “quality” of mate
45Indicator Traits (Sexual Selection – Ch. 17) Provide info to members of the opposite sex about the physical condition of the bearerChoosier sex (usually females) show preference for most extravagant traitsE.g., brightest colours, largest antlers, longest tail feathers, etc.
46Keeping signals HONEST: Zahavi & Zahavi’s “Handicap Principle”If signals are costly to produce (peacock tail), they tend to be honest indicators of condition or ability (i.e., in good health, well-nourished and free of parasites)(sexual selection)
47Functions of Communication Social Status/ AgonismDominance/submissive displays- avoid costly fightingTraits may also indicate social status (bigger, stronger males perceived as dominant) e.g., antler size in moosewolves and dogs
48Functions of Communication Female Belding's ground squirrel (Spermophilus beldingi) emitting an alarm call. (Sherman)AlarmAltruism or Selfishness?Alarm calls are given to warn other individuals about the presence of a nearby predator and are usually directed toward close kin.giving an alarm call increases the chance that the predator will attack the caller
49Functions of Communication AlarmVervet monkeys: Seyfarth & Cheney“semantics”- different calls for different predators (avian, ground)Pheromones as chemical alarm substancesinverts; mammalsSea urchins steer clearof an area where a urchinhas just been crushed
50Functions of Communication Finding Food“Information Centre Hypothesis”colonial organisms(e.g., communally roosting weaverbirds)hunting packs(African wild dogs)Giving/Soliciting Care, Play;Synchronization of Hatching (precocial birds – vocalize prior to hatching)
51Evolution of DisplaysCommunicative displays are believed to have evolved from noncommunicative behaviours through the process of ritualization:Ritualization = Evolutionary process by which behaviour patterns become modified to serve as communication signals.
52Ritualization (example) Food calling behaviour still seen in roosters may be evolutionary origin of courtship display seen in peacocksi.e., peacocks’ ancestors may have performed food-calling behaviour, which became ritualized into bow/feather spread display presently used
53Evolution of Displays “freezing” of movement into postures Stereotyping of behaviour (stays constant even under different levels of motivation)Development of conspicuous body structures- enlarged claws (fiddler crab), ornamental feathers (peacocks, male ducks), manes (lion), exaggerated fins (Betta)Crested Auklet (I. Jones)
54Displays may have arisen from… Intention movements - e.g., “powk” calls of BL Kittiwakes -- gannetsORDisplacement activities- innate, stereotypical responses to stimuli that seem inappropriate to the situationSome degree of conflict in organism’s motivation- e.g., strange female approaches: is a sexual or agonstic response needed?
55Displacement Activities Evolved into courtship display: During courtship, males may preen or touch own feathers (sham preening)Conspicuous feathers (sailfeathers) may have evolved and are exposed during this behaviourMandarin Duck
56Other origins of displays: Receiver bias - the increased sensitivity of perceptual systems to certain stimuli as a result of natural selectionSuch biases may influence the evolution of communicative displaysE.g., insect feeds mostly on yellow flowers, adapted to be sensitive to yellow in general, males with yellow are preferred, and may exploit this to attract females
58Honeybee communicative dances “Round Dance”Food nearby; less detailed“Waggle Dance”Food >200m away; more detailed
59Ceiling of hive = direction of sun (reference) Photo Caption: Diagram of the honeybee dance. (Credit: P. Kirk Visscher.)Ceiling of hive = direction of sun (reference)Angle of straight run (on vertical) = direction of food source relative to sun
60direction and duration of the straight run is critical antennae of hive members maintain contact with the dancer and taste samples of regurgitated food