Download Predation

Predation
Muzvondiwa J.V.
Outline
• There are a variety of antipredator
adaptations, which suggests that predation is
important in nature
• Predator–prey models can explain many
outcomes
• Field data suggests that predators have a large
impact on prey populations
Outline
• Experiments involving the removal or
introduction of exotic predators provide good
data on the effects of predators on their prey
• Field experiments involving the manipulations
of native populations show predation to be a
strong force
Predation
• Traditional view: carnivory
• Differences from herbivory
• Herbivory is nonlethal
• Differences from parasitism
• In parasitism, one individual is utilized for the
development of more than one parasite
• Predator–prey associations
Antipredator Adaptations
Aposematic or warning coloration
• Advertises an unpalatable taste
• Ex. Blue jays and monarch butterflies
• Caterpillar obtains poison from milkweed
• Blue jays suffer violent vomiting from ingesting
caterpillar
• Ex. Tropical frogs
• Toxic skin poisons
Camouflage
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Blending of organism into background color
Ex. Grasshoppers
Ex. Stick insects mimic twigs and branches
Ex. Zebra stripes: blend into grassy
background
Mimicry
• Animals that mimic other animals
• Ex. Some hoverflies mimic wasps
Types of mimicry
• Müllerian mimicry
– Fritz Müller, 1879
– Unpalatable species converge to look the same
• Reinforce basic distasteful design
• Ex. Wasps and some butterflies
• Mimicry ring: a group of sympatric species, often different
taxa, share a common warning pattern
• Batesian mimicry
– Henry Bates, 1862
– Mimicry of unpalatable species by palatable species
• Ex. hoverflies resemble stinging bees and wasps
Displays of intimidation
• Ex. Toads swallow air to make themselves
appear larger
• Ex. Frilled lizards extend their collars to
produce the same effect
Polymorphism
• Two or more discrete forms in the same population
• Color polymorphism
– Predator has a preference (usually the more abundant
form)
– Prey can proliferate in the rarer form
– Ex. leafhopper nymphs (orange and black)
– Ex. Pea aphids (red and green)
• Reflexive selection
– Every individual is slightly different
– Examples: brittle stars, butterflies, moths, echinoderms,
and gastropods
– Thwart predators’ learning processes
Prey phenologically separated from
predator
• Ex. Fruit bats
– Either diurnal or nocturnal
– Only nocturnal in the presence of predatory
diurnal eagles
Chemical defense
• Used to ward off predators
• Ex. Bombardier beetles
– Possess a reservoir of hydroquinone and hydrogen
peroxide
– When threatened, eject chemicals into "explosion
chamber"
– Mix with peroxidase enzyme
– Mixture is violently sprayed at attacker
Masting
• Synchronous production of many progeny by
all individuals in population
• Satiate predators
• Allows for some progeny to survive
• Common to seed herbivory