The informational
framework
• Information
Environment
Reception
reduces
Production
uncertainty
• Response
determines
fitness outcome
• Cues vs. signals
• Deceit
Based on Bradbury and Vehrencamp (1998)
Honest signaling
• Senders and receivers often
disagree on optimal response
– Mate choice, contests, etc.
• Pervasive dishonesty leads to
communication breakdown
• Only honest signals are stable
Maintaining
honesty
• Costs
–
–
–
–
Production
Maintenance
Vulnerability
Convention
• Constraints
– Index signals
Some properties of signals
•
•
•
•
•
•
•
Active space
Duty cycle
Locatability
Identification level
Modulation potential
Costs / constraints
Optimal signal design varies by
function
Signal evolution
• Sender precursors
– Intention movements
• Ritualization
– Cues
• Amplification
– Principal of
antithesis
• Receiver precursors
– Sensory drive
– Sensory exploitation
Communication networks
• Eavesdropping
– Intraspecific
• Black-capped
chickadees
– Interspecific
• Gryllus and
Ormea
• Audience
effects
Modalities
• Visual
• Acoustic
• Chemical
• Vibrational
• Electrical
• Multimodal
Sound I
pressure
•
•
•
•
Sounds are moving pressure waves
Amplitude = loudness
Frequency ≈ pitch = waves / second
Wavelength determines frequency
(because speed is ~ constant)
amplitude
wavelength
time
frequency is # of waves
that pass each sec
Sound II
• Waveform
• Spectrum
– Fourier transform
Amplitude
• Sonogram
Frequency
Sound production
• Vibration generator
–
–
–
–
Need for multiplier
Stridulatory organs
Larynx
Syrinx
• Resonator
– In anurans
– In humans
Goller and Larsen 1997 PNAS 94:14787-
Sound
transmission
• Air versus
water
• Degradation
– Global
attenuation
– Frequency
dependent
attenuation
– Reverberation
• Limits active space
– Frequency
dependent
attenuation
• Constrains use of
high frequencies
– Reverberation
• Constrains use of
rapid changes
wrens
– Global attenuation
tanagers
• Environment
constrains signal
structure
flycatchers
Acoustic adaptation
open
forested
Sound reception
• Ears
– Frequency
response
– Directionality
• Signal to noise
ratio
– Evolution of
urban bird
songs
Light
• The electromagnetic spectrum
• Radiance, reflection and
absorption
Visual signal production
• Pigments
– Carotenoids
– Melanins
• Structural colors
– Rayleigh scattering
– Mie scattering
• Bioluminescence
• Extended
phenotype
http://home.vicnet.net.au/~osch/Bower%20photo1.jpg
Visual signal reception
• Contrast with
background
• Available light
Olfactory communication
• Properties
– Slow
– Non-directional
– Non-spectral
• Volatility affects
duty cycle, active
space
• Trail following ants
• Territorial badgers
Electrical communication
• Only in fish
• Generate fields
– Strongly / weakly
electric fish
– Pulse / wave fish
• Social
communication
– Courtship “songs”
– Range: 1m
• Electrolocation
– Range: 2-5 cm
Vibrational
communication
• Widespread and
ancient
• Limited range,
bandwidth
• Private
• Recording
–
–
–
Geophones
Accelerometers
Laser Doppler
vibometers
• Playback
–
–
Shakers
Magnetic setups
Echolocation
• Principals
• Diversity
– Birds
– Cetations
– Bats
• In bats