• Information Information reduces reduces uncertaintyuncertainty

• Response Response determines determines fitness outcomefitness outcome

• Cues vs. signalsCues vs. signals• DeceitDeceit

The informational framework

Based on Bradbury and Vehrencamp (1998)

ProductionProductionEnvironmentEnvironment

ReceptionReception

• Senders and receivers often Senders and receivers often disagree on optimal responsedisagree on optimal response– Mate choice, contests, etc.Mate choice, contests, etc.

• Pervasive dishonesty leads to Pervasive dishonesty leads to communication breakdowncommunication breakdown

• Only honest signals are stableOnly honest signals are stable

Honest signaling

• CostsCosts– ProductionProduction– MaintenanceMaintenance– Vulnerability Vulnerability – ConventionConvention

• ConstraintsConstraints– Index signalsIndex signals

Maintaining honesty

• Active spaceActive space• Duty cycleDuty cycle• LocatabilityLocatability• Identification levelIdentification level• Modulation potentialModulation potential• Costs / constraintsCosts / constraints• Optimal signal design varies by Optimal signal design varies by

functionfunction

Some properties of signals

• Sender precursorsSender precursors– Intention movementsIntention movements• RitualizationRitualization

– CuesCues• AmplificationAmplification

– Principal of antithesisPrincipal of antithesis

• Receiver precursorsReceiver precursors– Sensory driveSensory drive– Sensory exploitationSensory exploitation

Signal evolution

• EavesdroppingEavesdropping– IntraspecificIntraspecific• Black-capped Black-capped

chickadeeschickadees

– InterspecificInterspecific• GryllusGryllus and and OrmeaOrmea

• Audience Audience effectseffects

Communication networks

• VisualVisual• AcousticAcoustic• ChemicalChemical• VibrationalVibrational• ElectricalElectrical• MultimodalMultimodal

Modalities

Sound I• Sounds are moving pressure wavesSounds are moving pressure waves

• Amplitude = loudnessAmplitude = loudness

• Frequency ≈ pitch = waves / secondFrequency ≈ pitch = waves / second

• Wavelength determines frequency Wavelength determines frequency (because speed is ~ constant)(because speed is ~ constant)

amplitude

frequency is # of wavesthat pass each sec

timepre

ssu

re

wavelength

• WaveformWaveform• SpectrumSpectrum– Fourier transformFourier transform

• SonogramSonogram

Sound II

FrequencyFrequency

Am

plit

ud

eA

mp

litu

de

• Vibration generatorVibration generator– Need for multiplierNeed for multiplier– Stridulatory organsStridulatory organs– LarynxLarynx– SyrinxSyrinx

• ResonatorResonator– In anuransIn anurans– In humansIn humans

Sound production

Goller and Larsen 1997 PNAS 94:14787-Goller and Larsen 1997 PNAS 94:14787-

• Air versus Air versus waterwater

• DegradationDegradation– Global Global

attenuationattenuation– Frequency Frequency

dependent dependent attenuationattenuation

– ReverberationReverberation

Sound Sound transmissiontransmission

Lake Forest

Acoustic adaptationopenopen forestedforested

flyc

atch

ers

flyc

atch

ers

tan

ager

sta

nag

ers

wre

ns

wre

ns

• Environment Environment constrains signal constrains signal structurestructure– Global attenuationGlobal attenuation

• Limits active spaceLimits active space

– Frequency Frequency dependent dependent attenuationattenuation• Constrains use of Constrains use of

high frequencieshigh frequencies

– ReverberationReverberation• Constrains use of Constrains use of

rapid changesrapid changes

• EarsEars– Frequency Frequency

responseresponse– DirectionalityDirectionality

• Signal to noise Signal to noise ratioratio– Evolution of Evolution of

urban bird urban bird songssongs

Sound reception

Light• The electromagnetic spectrumThe electromagnetic spectrum• Radiance, reflection and Radiance, reflection and

absorptionabsorption

• PigmentsPigments– CarotenoidsCarotenoids– MelaninsMelanins

• Structural colorsStructural colors– Rayleigh scatteringRayleigh scattering– Mie scatteringMie scattering

• BioluminescenceBioluminescence• Extended Extended

phenotypephenotype

Visual signal production

http://home.vicnet.net.au/~osch/Bower%20photo1.jpghttp://home.vicnet.net.au/~osch/Bower%20photo1.jpg

• Contrast with Contrast with backgroundbackground

• Available lightAvailable light

Visual signal receptionVisual signal reception

• PropertiesProperties– SlowSlow– Non-directionalNon-directional– Non-spectralNon-spectral

• Volatility affects Volatility affects duty cycle, active duty cycle, active spacespace

• Trail following antsTrail following ants• Territorial badgersTerritorial badgers

Olfactory communication

• Only in fishOnly in fish• Generate fieldsGenerate fields– Strongly / weakly Strongly / weakly

electric fishelectric fish– Pulse / wave fishPulse / wave fish

• Social Social communicationcommunication– Courtship “songs”Courtship “songs”– Range: 1mRange: 1m

• ElectrolocationElectrolocation– Range: 2-5 cmRange: 2-5 cm

Electrical communication

• Widespread and Widespread and ancientancient

• Limited range, Limited range, bandwidthbandwidth

• PrivatePrivate• RecordingRecording

– GeophonesGeophones– AccelerometersAccelerometers– Laser Doppler Laser Doppler

vibometersvibometers

• PlaybackPlayback– ShakersShakers– Magnetic setups Magnetic setups

Vibrational communication

• PrincipalsPrincipals• DiversityDiversity– BirdsBirds– CetationsCetations– BatsBats

• In batsIn bats

Echolocation