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Predators and prey. Predation = capture and consumption of one organism by another (includes herbivory). Predation provides strong selective pressure on prey populations. Favors adaptations to evade capture in prey and counter adaptations in predators (i.e.coevolution).

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Predators and prey
Predators and prey

  • Predation = capture and consumption of one organism by another (includes herbivory)

  • Predation provides strong selective pressure on prey populations

  • Favors adaptations to evade capture in prey and counter adaptations in predators (i.e.coevolution)

Where have all the sea otters gone?


Predators and prey1
Predators and prey

  • Morphological defenses:

  • Thorns, spines and prickles

  • Plant defenses against herbivory

  • Hairs (deter insect herbivores)

  • Grasses incorporate silica into cells

Where have all the sea otters gone?


Predators and prey2
Predators and prey

  • Chemical defenses:

  • Called secondary chemical compounds because not part of major metabolic pathways

  • Plant defenses against herbivory

  • Effects of secondary chemical compounds:

  • toxic (e.g. cardiac glycosides of milkweed)

  • interfere with digestion (e.g. tannins of oaks) or interrupt development of insects

  • interrupt development of insects

  • Secondary chemicals can be maintained in tissues at all times or released after damage by herbivores

Where have all the sea otters gone?


Predators and prey3
Predators and prey

  • Chemical defenses:

  • Some herbivores able to feed on plants protected with a certain secondary chemical compound (e.g. monarch butterfly larvae)

  • Plant defenses against herbivory

Where have all the sea otters gone?


Predators and prey4
Predators and prey

  • Chemical defenses:

  • Larvae of monarch butterflies feed on milkweeds and incorporate cardiac glycosides as own defense

  • Animal defenses against predators

  • Most predators learn not to eat monarchs

Where have all the sea otters gone?


Predators and prey5
Predators and prey

  • Chemical defenses:

  • Many species produce toxic chemical to deter predators

  • Animal defenses against predators

  • Poison-dart frogs produce toxic alkaloids in mucus covering skin

  • Bombardier beetle shoots 100oC irritant from abdomen

Where have all the sea otters gone?


Predators and prey6
Predators and prey

  • Defensive coloration:

  • Many species advertise their chemical defense through aposematic coloration

  • Animal defenses against predators

  • Yellows, reds, oranges and blacks (e.g. monarch butterflies)

  • Other species rely on cryptic coloration to avoid detection by predators

Where have all the sea otters gone?


Predators and prey7
Predators and prey

  • Behavioral defenses:

  • Dilution effect

  • Animal defenses against predators

  • Stay in large groups to overwhelm predator and reduce one’s own risk of capture (e.g. mayflies swarms)

  • Startle effect

  • Reveal coloration to cause hesitation by predator (e.g. Io moth)

Where have all the sea otters gone?


Predators and prey8
Predators and prey

  • Mimicry = evolution of coloration to resemble other species

  • Animal defenses against predators

  • Two general types:

  • Batesianmimicry: poisonous model and palatable mimic

Wasp (model) Mantid (mimic) Moth (mimic)

Where have all the sea otters gone?


Predators and prey9
Predators and prey

  • Mimicry

  • Müllerianmimicry: several unrelated, poisonous species with similar aposematic coloration

  • Animal defenses against predators

Where have all the sea otters gone?