Insects: Dressed for Success
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Transcript of Insects: Dressed for Success
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Insects:Dressed for
Success
Insects are the smorgasbord of the
animal world!
Who Eats Insects?
Who Eats Insects?
• birds• fish• arthropods (insect and non-insect)• amphibians• mammals• reptiles• humans• even plants!
Do insects take
this lying down?
Insects have an arsenalof defense mechanisms
Insects have an arsenalof defense mechanisms
• Morphological / Physical
• Chemical
• Behavioral
Insects have an arsenalof defense mechanisms
• Morphological / Physical– camouflage (crypsis)– mimicry– mechanical
• Chemical
• Behavioral
Insects have an arsenalof defense mechanisms
• Morphological / Physical– camouflage (crypsis)– mimicry– mechanical
• Chemical– toxins– venoms– pheromones
• Behavioral
Insects have an arsenalof defense mechanisms
• Morphological / Physical– camouflage (crypsis)– mimicry– mechanical
• Chemical– toxins– venoms– pheromones
• Behavioral– death feigning– “house” construction
CamouflageBlend into their background by looking like their background
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1) Morphological:
Blend into their background bybreaking up their body outline (disruptive coloration)
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…but it doesn’t work from every angle!
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Blend into their background bylooking like some uneatable part of their background
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Monarch butterfly = toxic
Viceroy butterfly = aposematically "dressed" because it doesn’t have the chemical toxins
1) Morphological:Mimicry
Aposematism: warning coloration
Looks like a bee, BUT this is actually a fly!Bee-mimic = No venom to back up aposematism
Mimicry:
• Batesian - the aposematic inedible model (monarch) has an edible mimic (viceroy)
- the model suffers, aposematic signal is diluted
Mimicry:
• Müllerian - both the model and the mimic are distasteful
- all benefit from co-existence because predators associate all aposematic color individuals as toxic
1) Morphological:
Mechanical
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2) Chemical:
PheromonesToxins: sequestered or produced
Venoms
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Chemically defended insects are typically very apparent to their
predators: warning colors
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Where do insects get their toxins?
3) Behavioral:
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3) Behavioral:DIY ‘House Building’
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These defense mechanisms often work in combination:
Toxins and venoms + aposematic coloration (or sometimes camouflage)
Camouflage + behavior
Mechanical + chemical
In some cases toxins and venoms can be costly for insects
to produce
Aposematic coloration = primary defenseVenoms and toxins = secondary defense
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Camouflage = primary defenseChemicals = secondary defense
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It’s not enough to look like a twig (or thorn, stick, etc.)
You have to ‘act’ like one to survive!
Camouflage +
Behavior
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This caterpillar is even MORE ‘painful’ than it looks
mechanical + chemical
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How did these defenses come about?
Evolution
By the process of Natural Selection
Governing principles of Natural Selection
• Populations of species have variability
• Variation is maintained by sexual reproduction
• Variations can be passed from one generation to the next
• Individuals that have variations (traits) that make them better able to survive (adapted) in their environment are more likely to survive and pass on their variation (traits/genes) to the next generation
Camouflage in caterpillars
First Generation
Second Generation
?
Third Generation
Other factors, in addition to natural selection, influence how species evolve
over time:
• Mutations• Genetic isolation
ReviewInsect Defense Mechanisms:
• Morphological / Physical– camouflage (crypsis)– mimicry– mechanical
• Chemical– toxins– venoms– pheromones
• Behavioral– death feigning– “house” construction