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Chapter 19: Ecology (The food chain (Tertiary consumers (Eat secondary…

- - - - Amount of energy converted to chemical energy by photosynthesis per unit time.
    - - Gross minus energy used by producers for respiration.
- - - - Aggressive species from Africa.
      - Bred to produce more honey than Italian honeybees.
      - Escaped from Africa.
      - Killed 10s million Americans.
    - - Originally from Asia.
      - Accidentally carried by a ship to the great lakes.
      - No natural local predators --> population exploded.
      - Caused lots of damage to pipes and risk out-competing local species.
  - - - Advantages
        
        Insecticides, herbicides, fungicides + rat medicines kill undesirable organisms.
        
        Increases food production.
        
        Kill animals that carry disease.
      - Disadvantages
        
        Exposure to toxins cause cancer.
        
        Natural selection means pests can return stronger than before.
    - - Methods
        
        Crop rotation - change the crop growing in the area.
        
        Introduce natural enemies of pests - but be careful not to disrupt ecological balance.
        
        Use natural pesticides.
        
        Insect birth control - Males can be sterilised with radiation.
- - - - Affected by age at which reproduction begins.
      - Life span that its capable of reproducing.
      - No. of offspring produced at a time.
      - No. of reproductive periods in a lifetime.
  - - - Many small young
      - Little or no parenting
      - Rapid maturation
      - Reproduce once
      - E.g. insects
    - - Few large young
      - Intensive parenting
      - Slow maturation
      - Reproduce many times
      - E.g. mammals
  - - - E.g. Lynx and hare. Hare eats grass. Lynx eats hare. Grass decreases, hare pop. fluctuates, lynx pop. fluctuates as well.
    - - Occurrence increases as pop. density increases.
      - E.g. Food, buildup of waste, disease
    - - Occurrence is not affected by pop. density.
      - E.g. natural disasters
- - - - Two species cannot coexist in a community if they share the same niche (compete for the same resources). One species will have an advantage over the other.
    - - Extinction
      - Resource partitioning: Evolve through natural selection to exploit different resources.
      - Character displacement: Divergence in adaptation.
  - - - Spines and thorns
      - Chemical poisons
    - - Active (but this costs a lot of energy)
        
        Hiding
        
        Fleeing
        
        Fighting
      - Passive
        
        Cryptic coloration/ camouflage
        
        Aposematic coloration
        
        Bright red/orange colouring to warn predators that the animal is poisonous.
        
        Mullerian mimicry
        
        2+ poisonous species that look similar gain an advantage in combined numbers.
        
        Batesian mimicry
        
        A harmless animal mimics the form of a poisonous one.
  - - - Plants
    - - Other animals
    - - Dead organic matter
    - - Symbiotic feeding relationship. Organism and host are both benefited.
    - - Symbiotic relationship. One organism is benefited and the other is not impacted.
    - - Symbiotic relationship. Parasite benefits while host is harmed.