Download Announcements Evolution of Metamorphosis Insects and Plants

Announcements
Quiz today.
Field trip dates
Pepperwood- Sun Feb 24
Galbreath- Sat Apr 26 or Sun Apr 27
Darwin Day and Biosystematists
Public tours of Essig Museum in afternoon
Darwin’s B Day party at 5:00
Biosystematists at 7:30 must submit list
today!
Evolution of Metamorphosis
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Occurred about 300 MYBP in Carboniforous
Coincided with evolution of seed plants
Two main types
Hemimetabolous
– Gradual change to adult form
– No pupal stage
– Includes true bugs
• Holometabolous
– True larval and pupal stage present
– Includes beetles, flies
Insects and Plants
• Very old associations
• Early plant fossils show insect damage
• Insects diversified as plants did
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Diversification in Mesozoic
• Diversification of insects that eat plant
feeding insects
• Appearance of Lepidoptera in Jurassic
Appearance of flowering plants in early
Cretaceous (130 MYBP)
• Diversification of insects associated with
flowering plants (Hymenoptera,
Lepidoptera)
Insect Body Plan (3 regions)
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‘Generalized’ insect
Insects vary a lot with respect to endoskeleton and
appendages
Orientation
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Dorsal
Lateral
Ventral
Appendages
– Proximal
– Distal
Functions of cuticle
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Forms exoskeleton
Prevents water loss
Provides support for muscle attachments
Lines tracheae and parts of digestive system
Varies in toughness
– Thick/hard, thin/flexible
– Depends on life stage
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Components of cuticle
• Waxes and lipids
• Proteins
• Chitin
– in fungal cell walls and arthropod exoskeletons
– unbranched polysaccharide polymer of high MW
Structure of cuticle
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Epicuticle
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Procuticle
– exocuticle and
endocuticle
– made of chitin and
protein
– Thickest layer
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Epidermis
– live cells
– secretes cuticle
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