Herbivory

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

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

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

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

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

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

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

Plant defenses 1) Physical defenses B) trichomes (

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

Plant defenses 2) Chemical defenses A) organic defenses

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

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

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

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

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

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

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

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

Boyd in Africa!

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

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

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

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

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

Plant defenses 3) Behavioral defenses: phenology

Plant defenses 3) Behavioral defenses: shed

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

Plant defenses 4) Crypsis: look like Camouflage: look Urban…

Plant defenses 4) Camouflage stone plants (Lithops):

Plant defenses

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

Plant defenses 4) Crypsis Mimicry: look Wasp Wasp mimics The Hair Band

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

Plant defenses 4) Mimicry Passiflora egg mimics: