Summary: Animal Ecology

Read the summary and the most important questions on Animal Ecology

• 1 Lecture 1

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• What two questions do foraging animals face?

  - What to eat and how much to eat from it?
  - Where to go and how long to stay?

• What happens with foregut animals?

  First fermentation
  - bad at digesting fibrous food thus limited in foraging

• What happens with hindgut animals?

  First enzymatic digestion

• Apparently speciaization/adaptation to

  1. Utilizing cell content (+plant secondary compounds)
  2. Utilizing cell wall (fiber)
  -> Leads to species which either browse or graze

• How does body size play a role?

  - Small body size -> diet high in protein
  - Large body size -> diet high in fiber

• What is the jarman-bell principle?

  1. Small animals have high mass specific energy requirements compared to large animals (small needs more energy per kg body mass)
  2. Easily fermentable substances yield more energy per time unit than cell wall constituents
  • small animals tend to be browsers, large animals grazers
  3. Browse and grass food items are differently distributed
  • Browse -> leaves are scarce and in small discrete units
  • Grass -> Leaves are abundant but mingled with stems 

• What is the optimal foraging prediction?

  Goal of the animal = Maximize E / Time
  - Energy (E) per unit time
  - Functional response or daily response

• How is selection with the optimal foraging theory?

  - If 2 prey types are available THEN select prey  type 2 if -> E/Time(1) < E/time(2) > E/time(1+2)
  
  - The energy gain when only taking prey 2 should be greater than when taking 1 or both 1 and 2

• Why is the optimal foraging prediction not always correct?

  • Plant world is too complex
    
  • Heterogeneity prevents optimal foraging
  • Plant world is changeable
  • Animals do not detect all nutrients
  • Other factors are not considered (predation, internal state)

  -> So model needs more constaints

• What is the satiation hypothesis?

  Animals react to satiation to both
  

  • Ingestion of nutrients (acquisition)
  • Ingestion of toxins (avoidance)

  
  
  - Through an interaction of sensory (flavor) and post-ingestive effects
  
  - This behaviour leads to balancing -> Consumption of a variety of foods
  
  - Recognize the importance of other factors
  

  • predation
  • cognitive mechanisms (learning to avoid/prefer)
  • Internal state (hungry/full)

  
  -> ONLY works with heterogeneity