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Herbivory

Herbivory. Herbivory. Importance? Great! Affects plant distribution Escape hypothesis : seed dispersal = escape herbivores. Seed shadow. Herbivory. Food chain. Why world green? What controls herbivores? Top-down control : Bottom-up control :. predators. herbivores. plants.

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Herbivory

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  1. Herbivory

  2. Herbivory • Importance? Great! • Affects plant distribution • Escape hypothesis: seed dispersal = escape herbivores Seed shadow

  3. Herbivory Food chain • Why world green? • What controls herbivores? • Top-down control: • Bottom-up control: predators herbivores plants

  4. Food chain Herbivory predators herbivores • Tritrophic interactions: Plants use • Ex, corn releases volatile • Volicitin (saliva) triggers VOC • Parasitic wasp plants

  5. Herbivory • Plant-plant communication • Ex, sagebrush (Artemisia tridentata) & wild tobacco (Nicotiana attenuata) • Damaged sagebrush lvs.

  6. Herbivory • How plants handle herbivory? • 1) Resistance: • 2) Tolerance:

  7. Plant defenses • Physical • Chemical • Behavioral • Crypsis (camouflage/mimicry) • Associational

  8. Plant defenses (Bottom-up) • 1) Physical defenses: • A) pointy things • Spines? • Thorns? • Prickles?

  9. Plant defenses • 1) Physical defenses • B) trichomes (

  10. Plant defenses Shadow Battlecrab: Babylon 5 • 1) Physical defenses • C) sharp cells: astrosclerids

  11. Plant defenses • 2) Chemical defenses • A) organic defenses

  12. Plant defenses • 2) Chemical defenses • A) organic defenses • 1) indigestible carbohydrates (cell walls): cellulose & lignin

  13. -ine! Plant defenses • 2) Chemical defenses • A) organic defenses • 2) toxins: small molecules, low dose • ex: alkaloids • (end -ine): caffeine cocaine coca plant

  14. Plant defenses • 2) Chemical defenses • A) organic defenses • 2) toxins • ex: terpenes & terpenoids.

  15. Plant defenses • 2) Chemical defenses • Ex: terpenes—pyrethroids • monoterpenes (10 carbons) from Chrysanthemum

  16. Plant defenses • 2) Chemical defenses • A) organic defenses • 2) toxins • ex: cyanogenic glycosides: release Found in >2500 plant species!

  17. Plant defenses • 2) Chemical defenses • A) organic defenses • 3) digestibility reducers: large, • Bind proteins: digestive • ex, tannins (polyphenols) phenol

  18. Plant defenses • 2) Chemical defenses • B) elemental defenses: From • Silicon (Si): phytoliths cell walls

  19. Plant defenses • 2) Chemical defenses • B) elemental defenses • Metal hyperaccumulation • Ex: >1,000 ppm dry weight Ni

  20. Boyd in Africa!

  21. Elemental Defense • Senecio coronatus • Ni hyper. (12,100 µg Ni/g) & non-hyper. (680 µg Ni/g) pops. on serpentine Test herbivore?

  22. Elemental Defense • Snails: choice high-Ni/ low-Ni leaf • Mean % damage • Hyperaccumulator: 1.9% • Non-hyperaccumulator: 20% Helix aspersa

  23. Defense against pathogens • Ex, bacterium Xanthomonas campestris • Bioluminescence gene • Streptanthus polygaloides, glowcolony shaw

  24. Defense against pathogens • Inoculate low-Ni S. polygaloides • Growth after 72 hr. Ambient light No light

  25. Defense against pathogens • Inoculate high-Ni S. polygaloides • Growth after 72 hr. Ambient light No light

  26. Plant defenses • 3) Behavioral defenses: phenology

  27. Plant defenses • 3) Behavioral defenses: • shed

  28. Plant defenses • 4) Crypsis: look like Biological version of “where’s waldo?”

  29. Plant defenses • 4) Crypsis: look like • Camouflage: look Urban…

  30. Plant defenses • 4) Camouflage • stone plants (Lithops):

  31. Plant defenses

  32. Plant defenses • 4) Camouflage • stone plants (Lithops): Stone(d) plants

  33. Plant defenses • 4) Crypsis • Mimicry: look Wasp Wasp mimics The Hair Band W.A.S.P.

  34. Plant defenses • 4) Mimicry • Passiflora (passionflower) leaves • Heliconius: Heliconius butterfly

  35. Plant defenses • 4) Mimicry • Passiflora egg mimics:

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