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Download Different anti-predator strategies Different anti-predator strategies Individual Make yourself unpalatable/toxic

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  • Different anti-predator strategies Individual

    Make yourself unpalatable/toxic Aposematism Feign death

    Startle predator Mimic a predator Evolve large size

    Social Mutual defense

    Improved vigilance Confusion effect

    Dilution effect

  • Monarch butterflies have aposematic coloration,

    bitter taste, and heart poisons in their body that

    are toxic to most vertebrates

    Naïve bluejay eating a monarch butterfly

    Same bluejay reacting to ingested

    monarch

    Same bluejay barfing several minutes later

  • Many predators have an innate avoidance response to aposematically colored prey items

    Wooden snake models were used to test feeding responses

    of naïve, hand-reared Motmots (a type of bird)

    Note that the motmots avoided the models that most

    resemble a coral snake

    The numbers indicate how many pecks were delivered to each part of the “snake”

  • Many insect have toxic sprays or exudates that are

    exceedingly noxious to predators

    Bombadier beetles can direct their caustic spray in any direction

  • Some snakes and rodents can feign death quite convincingly

  • Prey species can often startle predators by suddenly appearing like a predator

    Mexican vine snake

    Sphingid caterpillar

  • Prey mimics predator

    Front view of a zebra jumping

    spider

    Posterior view of a snowberry fly

    The wing banding pattern, and associated wing movements of the strawberry fly display, appears to make this fly look like an aggressive jumping spider, and causes many jumping spiders to flee

  • Large size has its advantages

    Packs of wolves are often unsuccessful at capturing

    large mammalian prey

  • Sociality can be viewed as an anti-predator defense, particularly when young are threatened

    e.g., mutual defense of young against predators by musk-oxen in a circular formation

  • Improved vigilance The larger the flock of wood pigeons, the

    sooner it detected an approaching goshawk (as indicated by reaction distance)

    The larger the flock of wood pigeons, the more difficulty goshawks

    encountered in their stealth attacks

    How can you explain this

    result?

  • Response of a flock of European starlings to an approaching peregrine falcon

    Before After

    What is the functional significance of this flocking response? How might it benefit an individual? What is the selfish herd hypothesis?

  • Cuttlefish Squid Pike Perch

    Hunting success as measured by capture/contact ratio for 4 predators as a function of school size

    Contact involved any discovery of a prey by a predator prepared to hunt Hunting success decreased with school size, presumably owing to confusion effect

  • Diagrammatic representation of two types of oddity

    Odd prey contrast to group members plus background

    Odd prey contrast to group members only

    When predators attack a flock of birds or schools of fish, they to focus on the odd individuals, presumably because this helps them

    overcome the confusion effect How might this attribute of predators influence the evolution of coloration

    patterns in prey?

  • Dilution effect in penguins

    Young birds time their departure from the nesting colony to coincide with that of

    many other fledgling guillemots (a type of penguin). Even though the parents (large

    bird) accompany their young, only those youngsters that fledge at the peak

    departure time are likely to survive the waiting predators.

    Adelie penguins have to cope with formidable predators like this leopard seal, which attack penguins (particularly young

    and vulnerable ones) as they enter the water

  • Dilution effect in mayflies

    The more female mayflies emerging on a June evening, the less likely any one mayfly is

    to be taken by a predator.

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