a13 populations (1.1/2/3)

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  • Created by: phebez
  • Created on: 06-10-15 18:52
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  • A population is all the organisms of 1 species in a habitat.
    • within a habitat a species occupies a niche governed by adaptation to both biotic and abiotic conditions
    • A13 POPULATIONS
      • INVESTIGATI-NG POPULATIONS
      • VARIATION IN POPULATION SIZE
        • BIOTIC
          • concerned with the activities of living organisms and include competition and predation
  • QUADRATS/ TRANSECTS
    • FACTORS: size ; number of sample quadrats (larger number of quadrats =more reliable) ; position of each quadrat
    • transects : line or a belt
    • abundance is measured by either frequency or % cover.
      • frequency is the likelihood of a particular species occurring in a quadrat
      • % cover is an estimate of the area within a quadrat that a particular plant species cover
    • INVESTIGATI-NG POPULATIONS
  • some time later, a given number of individuals is collected randomly
    • number of marked individuals recorded
    • they are released back into the community
      • A known number of animals are caught and marked
        • MARK RELEASE RECAPTURE
    • 1)slow growth- initially small # of individuals reproduce to slowly build up their number
      • 2)rapid growth- ever-increasing # of individuals continue to reproduce
        • 3)stable- declines due to food supply or to increased predation until more or less stable
      • population growth curves
        • VARIATION IN POPULATION SIZE
          • BIOTIC
            • concerned with the activities of living organisms and include competition and predation
    • TEMPERATURE
      • the more energy the organisims expend in trying to maintain their normal body temp.
        • this leaves less energy for individual growth-mature more slowly-reproductive rate slows- population gets smaller
      • ABIOTIC
      • WATER/ HUMIDITY
        • affects transpiration rates in plants and the evaporation of water from animals
        • ABIOTIC

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