Communication

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Communication

• Lecture 6

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Animal communication

• Animals communicate a variety of types of
  information
• Location of food, social status
• Humans are highly visual but some animals use
  high developed olfactory or vibratory
  communication systems
• In this lecture
• Mechanisms of communication
• Functions of communication signals

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Olfactory communication

• Humans are visually oriented
• Many mammals rely more heavily on olfaction
• Many rodents have elaborate scent marking rituals
  that may involve
• Marking territories
• Mates
• Favourite roosts or perches

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Olfactory communication

• Specially designed glands and scent dispersing
  hairs
• Osmetrichia

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Pheromones

• Insects use chemical pheromones to attract mates
• Female gypsy moth
• Human pheromones
• Signals immune system compatibility

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Visual communication

• Red wing patches of Red-winged blackbird
• Some primates signal onset of ovulation

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Vocal communication

• Birds
• Insects
• Anurans (frogs and toads)
• Mammals

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Vocal communication

• Male Male communication
• Maintaining territory boundaries
• Male Female communication
• Signalling quality
• American Toad
• Communication among group members
• Chickadee flocking call

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Tactile communication

• Spiders and many other invertebrates use
  vibration
• Some mammals also use vibrations
• e.g. some rodents, elephants

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Anti-predator behaviour

• Monarch Aposematic (warning colouration)
• Artiid moths Aposematic colour and sounds (clicks
  that warn bats)
• Sounds may have other functions as well
• Startle reactions

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Foraging behaviour

• Flock communication
• Chickadees
• Predator detection
• Alarm calls
• Information about feeding locations
• Bee dance
• birds

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Language and semantic communication

• Language was once used as the one feature that
  distinguished humans from other species
• But recent evidence suggests that other species
  have at least simple forms of language and
  semantic communication

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Vervet Monkeys

• Have different calls for different kinds of
  predatory threats
• Leopard call
• Snake call
• Eagle call

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Vervet Monkeys

• Respond differently depending on the type of
  signal
• Leopard call head for trees
• Snake call scan the ground
• Eagle call vervets scan sky

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Vervet Monkeys

• Also respond differently to two types of calls
  given by superb starlings
• Respond appropriately depending on the type of
  starling call they hear

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Eavesdropping and information piracy

• Communication signals may also be available to
  individuals and species other than the intended
  recipients
• Some species eavesdrop on communication signals
  to locate food
• Others mimic the communication signals of other
  species for the purposes of deception

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Eavesdropping and information piracy

• Male crickets (Gryllus integer) call to attract
  female mates
• Their calls also attract satellite males who wait
  and intercept the females
• Parasitic flies also use the signals to find host
  males on which to lay their eggs

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Eavesdropping and information piracy

• Bats use feeding buzzes (calls indicating attacks
  on prey) of other bats to locate patches of prey
• Chrotopterus turn off echolocation and use vision
  on moonlit nights

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Signals used to attract mates

• Are often exploited by predators
• Male frogs of many species call to attract mates
• Bats (Trachops chirosus and Nycteris grandis) use
  the vocalizations of these frogs to prey on them
• Nycteris eats only the male frogs

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Results
Predation on calling males
Gender bias is predation rates
Skewed sex ratio
Evolution of mating systems
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Deceptive signalling

• Monarchs use their conspicuous colouration to
  advertise the fact that they are unpalatable
• The viceroy butterfly is perfectly edible but
  gains protection by mimicking the monarch
• Batesian mimicry

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Deceptive signalling

• Mullerian mimmircy
• Both species are unpalatable but resemble each
  other
• Speeds up the learning process because there are
  more opportunities to learn to associate the
  colour pattern with the taste

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Deceptive signalling

• Fire flies
• Photuris and Photinus
• Communicate using light flashes
• Chemical reaction abdominal light organs
• Females flash in a species-specific pattern to
  attract mates

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Deceptive signalling

• Fire flies
• Female Photuris prey on male Photinus
• Photuris females mimic the calls of Photinus
• Male Photinus approach expecting to find a mate
• Instead find themselves becoming lunch for a
  hungry Photuris

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Deceptive signalling

• Fire flies
• Female Photuris gain nutrients
• Photinus produce defensive chemicals
• Photuris cant make the chemicals
• After eating Male Photinus, the Photuris acquire
  the protection

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Conclusions

• Communication is sometimes mutually beneficial to
  both sender and receiver
• Directional selection may lead to exaggeration of
  the signal

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Conclusions

• Communication is sometimes constrained by
  stabilizing selection
• e.g., alarm calls in birds

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Conclusions

• Communication is sometimes a trade-off between
  the benefit of being understood by a receiver and
  the risk of information being pirated by
  predators or competitors

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Evolutionary Arms Race
2 evolution of insect ears
1 evolution of echolocation
3 Visual hunting