BI0004 - Lecture 12 - Signalling 1

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  1. What are 'External' signals?
    External’ Signals:

    Receiving and responding between animals

    Signalling between plants and animals
  2. What are signals between cells?
    • Nerve impulses
    •     Sensory reception

    • Hormones
    •     Plants / Animals
  3. What types of signals are there?



  4. What part of the electromagnetic spectrum do humans see?
    Humans see in the visible spectrum and only directly perceive a tiny fraction of the world
  5. Which animals see in the infra red range?
    Just two animals known to see in the infrared range:

    1. Pit vipers and boas use infrared to detect warm-blooded prey at night.

    2. Some beetles e.g. species of Buprestidae, whose larvae infest trees recently killed by fire, uses infrared to locate smoldering tree trunks.

    Vipers and boas do not use their eyes to detect heat released by their warm-blooded prey – they use pit organs
  6. How do insects see?
    They can see in the ultraviolet part of the spectrum too
  7. How can cats and dogs see?
    Cats and dogs can see the colour blue, but are insensitive to red, yellow, and green.

    Rely more on contrast and movement.
  8. What types of colour vision are there?
    • Monochromatic vision – no pigments
    •     Pinnipeds (e.g. seals)
    •     Cetaceans (e.g. whales)

    • Dichromatic vision – 2 pigments
    •     Many insects,
    •     Most mammals, including dogs

    • Trichromatic vision – 3 pigments
    •     Primates (humans), bees and some other insects

    • Tetrachromatic vision – 4 pigments
    •     Birds,
    •     Some butterflies
  9. What are visual signals used for?
    Attracting a mate

    Displaying dominance or submission

    Indicating food sources

    Warning signals
  10. How do honeybees communicate?
    Honeybee dance language:

    Workers surround a returning forager bee

    A round dance shows food is close by

    Waggle dance:

    • Distance is relayed by duration of each waggle and number of waggles per dance
    • Direction is indicated by the angle of the dance relative to the vertical i.e. in relation to the sun
  11. What is bioluminescence?
    Animals producing light as a visual signal

    Glow worms:

    Not worms but beetles.

    The light-producing organs of the female glow-worm are contained in the last three abdominal segments

    Light is produced by enzymatic reaction between the substance luciferin and oxygen.

    The light emitted is pale green and can be switched on and off

    The light attracts the male glow-worm, who quickly fly towards the light
  12. What is aposematic colouration?
    • Warning colouration
    • i.e. advertisement- Honest signal

    There are many ‘poison dart’ frog species in S. America. They have extremely toxic skin secretions and highly distinctive colour patterns.

    Handle with care!!!!!!!
  13. What is batensian mimicry?
    Batesian mimicry occurs when a harmless species mimics a harmful one.

    Mimicry can involve behaviour, but also shape and colour pattern

    Hawkmoth larva puffs up its head to mimic the head of a snake
  14. What is deceptive coloration?
    Deceptive coloration: moth with "eyeballs“

    Shock and awe tactics to repel potential predators

    Dishonest signal
  15. What are pheromones?
    • Pheromones:
    •     Small molecules released into external environment
    •     Volatile or water-soluble

    • Functions include:
    •     Marking trails
    •     Leading to food
    •     Defining territories
    •     Warning of predators
    •     Attracting mates
  16. What is bombykol?
    The pheromone bombykol is released by the female silkworm moth to attract a mate

    Bombykol is detected by special chemical receptors on the antennae of the male

    The antennae of the silkworm moth Bombyx mori are covered in hairs (lower panel), which contain some of the most sensitive chemoreceptors known and detect female sex pheromones
  17. What complex pheromonal communication system do honey bees have?
    Honey bees have 15 glands that produce different pheromones

    A range of pheromones are secreted by the queen, drone and worker bee

    • Examples:
    •     Alarm pheromones i.e. released when the bee stings another animal and promotes defensive behaviour
    •     Foot print pheromones i.e. left where bees walk and helps search for food

        Nasonov pheromones which orient forager bees back to the colony
  18. How do minnows use chemical communication?
    Injured minnows produce an alarm pheromone that induces a fright response in other fish

    Artificial introduction of the alarm pheromone promotes the fright response
  19. What do territorial mammals do?
    Territorial mammals mark territories by olfactory signals

    Provides information on:

    Territory demarcation

    Transmits information about the sender e.g. female ready for mating

    Avoids dangerous encounters between animals
  20. What do bird sounds do? (Auditory communication)
    Indicate territory and attracts a mate

    • Divided up into songs and calls:
    •     Songs:- long and complex , heard mainly in breeding season
    •     Calls:- short, produced all year and signals flight or danger

    Each species has own song repertoire

    Repertoire varies with each bird

    Example: auditory communication is particularly important in woodlands where visual cues are difficult to see due to the tree canopy

    Woodland birds are not very colourful

    Rely on song/calls for communication
  21. How can auditory communication be crucial in social groups?
    Example: Alarm calls in vervet monkeys

    Produce a complex set of alarm calls

    • Call varies with predator:
    •     Barking sound – leopard
    •     Short double cough – eagle
    •     Chutter - snake

    Young vervets learn the calls by re-enforcement by the adult
  22. What are infrasound and ultrasound?
    Humans are deaf to ultra and infrasound, but other animals to use it to communicate.

    When elephants trumpet, they also produce infrasound reaching other elephants as far as 10 kilometres away

    Mammals such as dolphins and whales communicate with utrasound ‘clicks’
  23. What is tactile communication?
    Touch e.g. grooming, stroking, beak tapping is an important form of communication:

    Strengthens bonds between group or mating pairs
  24. What does drosophila courtship involve?
    Drosophila courtship involves visual, chemical, tactile and auditory communication:

    Male visually recognises female and female produces pheromones

    Male taps female’s abdomen with his foreleg

    Male vibrates wing to produce a courtship song
  25. What is the benefits of signalling between plants and animals?

    Plants need pollination by animals to reproduce

    Animals get food reward
  26. What is pollination?
    Pollination: The transfer of pollen from the male anther to the female stigma
  27. What is the function of a flower?
    Function of a flower:

    To attract pollinators with colourful petals, scent, nectar and pollen

    Colour is an advertisement in many plants (and animals!)

    Many flowering plants rely on animals for cross-pollination:
  28. In pollination, what is the benefit for the pollinators?
    Plants advertise their pollen and nectar rewards with:

    • Colours:
    • - Bees see blue, yellow, UV
    • - Birds see red
    • - Bats don’t see well, so flowers are white.

    • Nectar or honey guides:
    • - a visual guide for pollinator to locate the reward (e.g. pansy flower)

    • Aromas:
    • - For insects: nectar, carrion or dung smell
  29. What benefit do insects have when finding nectar?
    Insects see UV and can detect the nectar guides provided by the plant which are not visible to the human eye

    NB. Some nectar guides are visible e.g. Dalmatian toadflax (right) has yellow flowers with orange nectar guides
Card Set:
BI0004 - Lecture 12 - Signalling 1
2014-05-14 16:22:51
BI0004 Lecture 12 Signalling
BI0004 - Lecture 12 - Signalling 1
BI0004 - Lecture 12 - Signalling 1
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