Predation (with parsitism and herbivory)

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Predation (with parsitism and herbivory) When one
animal (a predator) eats (and kills) another
animal (a prey), the predator clearly benefits
() and the prey is harmed (-). When one animal
feeds from the body of another (the host) without
killing it, the interaction is called parasitism.
The parasite benefits () and the host is harmed
(-). When an animal consumes plant material, the
interaction is called herbivory. The herbivore
benefits () and we normally assume that the
plant is harmed (-).
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Now think about these interactions in
evolutionary terms. The species that is harmed is
under more-or-less severe selective pressure to
minimize the harm. There are an enormous variety
of defensive adaptations in both animals and
plants. Here are a few examples from the plant
world Plants cant run and hide, so most of
their defenses are either structural or chemical.
The more interesting ones are chemical
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• Do you like chocolate? What gives chocolate
• much of its flavor is an alkaloid (a toxin)
  thats present to protect the beans from insect
  herbivores.
• 2.Do you like cinnamon? It comes from the bark of
  a tree. The flavor is a toxin (here cinnamic
  acid) again present to protect the bark from
  insect herbivores.
• 3. Lets save time an space. Virtually every
  strong flavor we like (pepper capsicic acid, )
  has evolved in the plant source for protection
  from insects.

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And the structural defenses are fairly obvious
Thorns, hooks, spikes, or prickles in plants
and spines (porcupine quills) in animals,
e.g. cactus
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• In animals there is a greater variety of
  approaches to defense.
• Warn a potential predator that youre dangerous
• (or even poisonous).Its called aposematic
• coloration

The warning colours are generally stripes of red
and/or yellow contrasted with black. All 3 colors
are seen in coral snakes yellow and black are in
bees and wasps.
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2. Crypsis (or camouflage) hiding in plain
sight. Think of other examples like stick
insects or insects with leaf-like wings,
Against an artificial background In its
natural habitat
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3. Mimicry if you cant hide, try looking like
something the predator wouldnt want to eat.
There are two kinds of mimicry Batesian,
where the mimic tastes good, and the model is
distasteful, or Mullerian, where both model
and mimic are distasteful.
Batesian mimicry Hawkmoth left Snake - right
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Probably the most famous example of Batesian
mimicry is the Monarch (model) and Viceroy
(mimic) butterflies
The Monarch is distasteful, even causing bird
predators to vomit.
The Viceroy is not distasteful (it may even taste
good)
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Blue jay vomiting after eating a noxious monarch
butterfly. The caterpiller obtains poison from
its milkweed host plant.
Photo Lincoln P. Brower, Univ. of Florida
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In Müllerian mimicry 2 different species resemble
each other, e.g., wasps bees are both black
yellow. The advantage to the prey is that
predators are quick to learn to avoid both
species.

The model a hornet A beetle mimic
fly moth
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Deceptive colouration - eyespots attract
predators to attack places on the body that do
not result in fatality. The eyespots are intended
to make the prey look like a frightening
predator. They may also have displays that at
least momentarily frighten a predator.
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Animals may adopt chemical defenses, too. Some
molluscs secrete sulfuric acid, and are rejected
as food by fish A number of animals use defensive
sprays. Whip scorpions (related to spiders) spray
acid.
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Skunks spray a concentrated musk (mercaptan) that
we can all agree is effective in defense against
attack. Dendrotoxin (which blocks potassium
channels in the predators nerve cells) is in the
skin of certain poisonous frogs, and used by
hunters in the Amazon rainforest. Tetrodotoxin
(used in neurophysiological research) comes from
the puffer fish. It blocks sodium channels.