Predators & Prey

Predation on plants: herbivory

Whole Plant Predation

Phytoplankton Predation

Defoliation

Wood Boring

Sap Sucking

Seed & fruit predation

Effects on Fitness:

Grazer stimulated production: Bacteria, grasses

Removal of meristems

Replacement of tissue in some plants drains reserves

Replacement leaves smaller, reduces ability to capture energy

Conifers cannot replace needles

Stimulation of plant defenses: energettic cost

Science 279:1201 induced plant defenses and fitness

Plant communication: ethylene gas, NO

Secondary Metabolites: Natural Products

Impede digestion; tannins, antimicrobials

Toxic, adversive: terpenes, cardiac glycosides, alkaloids

Hormone mimics: isoflavanoids mimic estrogen- infertility, difficult labor, reduced lactation

Capillars and horse deaths in Kentucky

Herbivore response to secondary metabolites:

Chemical cue: locating food source, triggering reproduction in montaine voles

Mixed function oxidase (MFO): detoxifying enzyme

Assimilating Defense: monarchs, sea slugs

Plant Mimicry:

Passiflora spp: leaf mimics of inedible species, egg mimics

Structural Defenses

Tough leaf tissues, cuticles

Spines, hairs

Hard coated seeds

Predator satiation: delayed, focused, and cyclical production of seeds

Animal Predation:

Chemical Defenses

Mimicry

Batesian

Muellarian

Semelparity as a defense Fig. 16.17

Predator-Prey Cycles

Lynx-Hare Fig 16.19