Communication
Communication
“Action by one animal that alters the behavior
of another animal in a way that is adaptive to
one or both participants”
Requires some degree of intentionality
Signals
Signals
signal
receiver
sender
discrete signal
“categorical”
graded signal
“continuous”
Signal = manifestation
of communication
Evolved for that function (e.g. not body size)
Signals
Some signals change the meaning
of signals that follow (= metacommunication)
1 Intraspecific communication
Position of
sun’s azimuth
on horizon
von Frisch: successful foragers
convey vector information to naïve
hive mates via waggle dance
What provides directional information?
The honey bee waggle dance
The honey bee waggle dance
How do they keep track
of distance traveled?
Honeybee forager
trained on feeder
directly toward
sun’s azimuth
Ability to compensate for sun’s
movement requires biological clock!
Waggle dance controversy
If blinded, forager
continues dancing, but
artificial “sun” influences
interpretation of dance
Interspecific communication?
California ground squirrel
Recruits’ flight time
longer than expected
Infrared tail stimulus
causes snakes to
adopt defensive posture
Rattlesnakes detect
ground squirrels with
thermoreceptors
Resolution requires quantitative evaluation of bee flight paths….
But is this
a signal?
2 Interspecific communication
Interspecific communication
California ground squirrel
Rattlesnakes detect
ground squirrels with
thermoreceptors
Response to
gopher snake, which
lack thermoreceptors
Signal evolution
Signal evolution
Signal may evolve for one function,
then be co-opted for another
Signals may evolve to exploit preexisting biases in sensory systems
spotted bowerbird
Signal evolution
Parsimony suggests
ancestor was
swordless
Female maculatus
prefer swords!
Sceloporus virgatus
lack blue ventral patches
S. virgatus respond to
artificial blue patches
Close relatives
have them
3 Exploiting a sensory bias
Exploiting a sensory bias
Population mean
frequency of
“chucks” = 2.55 kHz
Male túngara frogs produce
simple (whines) or complex
(whines + chucks) calls
Best frequency of
basilar papilla in
ear = 2.13 kHz
Preferred by females
túngara frog
Mike Ryan
Similar tuning in
ear of coloradorum,
which lacks “chuck”
Why do females prefer complex songs?
Handicap principle
Harris’s sparrow
Why produce such costly signals?
Elk
Costly signals are more likely to be honest
indicators of quality, therefore should be
more salient to conspecifics
Amotz Zahavi
European toad
Honest signaling
Number of attacks
by intruders
Honest signaling
European toad
High pitch
Low pitch
Small male defender
High pitch
low pitch
Large male defender
4 Honest signaling
Costs of signaling
Talk is cheap, at least in birds
Honesty enforced by costs
1. Energetic costs
2. Third party interception
a. Predators, parasites
b. Conspecifics (eavesdropping)
14% raise in metabolic rate in
singing canaries
Costs of signaling
Costs of signaling
number of push-ups
threat posture duration
Energetic costs of display may be greater in lizards
baseline
endurance
reduced
endurance
Minimal cost of singing
in pied flycatchers
May be intercepted by unintended receiver
Photuris female
baseline
endurance
reduced
endurance
Threat posture compresses
body, increases anaerobic
respiration (lactate in blood)
Costs of signaling
Photinus male
Why “femme fatales”?
Photinus pattern
indicated by “F”
Costs of signaling
Complex túngara frog calls are attractive
to other animals as well…
Photinus produce lucibufagins
Photuris do not
Palatable
Photuris female
Photinus male with
lucibufagins
+
Unpalatable
Photuris female
=
5 Costs of signaling
Costs of signaling
What would you predict about complex calls
given by solo males versus males in groups?
Positive phonotaxis
to chucks by
blood-sucking flies
Eavesdropping
Third party gains information from an interaction
that could not be obtained from the signal alone
Eavesdropping
Betta splendens
Latency to approach
Latency to display
“white”
loses
“white”
wins
Winners, losers in “seen”
and “unseen” interactions
sequentially put into
tank with subject male
6
Bio 281 2011 Lecture 12 - Communication
of 6
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