Read the summary and the most important questions on Ecology Final

• Ecology Final

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• List of Plant Adaptations to Herbivores

  • Structural Deterrence
  • Chemical deterrence
  • Plant communication?
  • Allocation of plant resources

• Plant Structural Deterrrence

  Adaptations can. . . 
  

  • Lower nutrient availability
  • Become less palatable

  
  Morphological deterrents:
  

  • Thorns/spines
  • Tough seed coats
  • Sticky sap/resin
  • Structural elements (silica in leaves)

• Plant's Chemical detterence

  Secondary Compounds
  

  • Metabolic by-products
  • De novo adaptation

  Types of Chemical Compounds
  

  • Repelients (tannins)
  • Toxins
  • Hormone/pheromone mimics

• Allocation of plant Resources

  E trade off: reproduction <--> defense <--> Growth
  Evolutionary "decision" in E allocation
  

  • Spatial/temporal vulnerability --> Energy cost/benefit to deter grazer

  
  Factors involved in "decision"
  

  1. Availability of plant to herbivores
  2. Plant architecture
  3. Seasonal scarcity
  4. Specialized herbivores involved?

• Herbivory Mostly negative effects on plants

  Evolutionary time (long term)
  

  • Eating seeds: decrease in plant fitness

  
  Ecological time (short term)
  

  • Decrease photosynthesis and E to replace leaves

• Herbivory Grazing may be beneficial for plants

  Grazing can increase:
  

  • Seed production
  • Biomass production
  • Nutrient Content

  
  How do these effects this come about?
  

  • Removal of old leaves (b/v take more energy to upkeep older leaves)
  • Alternation of hormone distribution
  • Increase productivity to compensate for loss

  
  
  2 1/2 : 1 Fitness

• OFT (Optimal Foraging Theory) Definition

  Maximum possible energy return (E) under a given set of foraging conditions
  
  2 groups

• Fundamental assumptions of OFT

  1. Foraging is genetically controlled (as a result, it can be shaped by natural selection)
  2. Fitness is related to net E intake (Fitness has to be linked to how much energy the forager is taking in)

  
  
  Net E = Total E consumed - foraging E

• Marginal Patch Theory

  Increase time spent; decrease food (E) in patch
  Predator leaves, spends E to travel
  
  
  Decision: E gained at time it leaves E gained levels off, time to go
  
  Patches Closer Together
  

  • Travel time is low
  • Energy loss associated with travel decrease
  • Spend less time in original patch

  
  Patches Far apart
  

  • Travel time is high
  • Too much energy spent on traveling
  • More time spent in Original patch

• Three Components to Calc. E Gain rate

  1. Energy content of food resource
  2. Search Time
  3. Handling Time