Populations

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  • Population
    • A population is a group of individuals of the same species living in the same habitat at the same time.
      • Populations are also described as DYNAMIC  -it will change
    • Changes in population
      • Birth rate - death rate - Immigration - Emigration - (factors that affect populations density)
        • These changes affect the population density i.e the number of individuals per unit area.
          • Birth rate increases = population would increase. (in that area)
    • Abiotic -  non-living factors
      • Light
      • Temperature
      • Wind and water currents
      • Water availability
      • Oxygen availability
      • Soil structure
      • Mineral content of soil
      • Toxic waste
      • Weather
      • Density independent factors =  the effect of these factors on the population will remain the same regardless of it's size.
    • Biotic factors  -living factors
      • Competition
      • Predation
      • Parasitism
      • disease
      • Overcrowding
      • Density dependent factors = the effect the factor has on a population is dependent of the size of the population size itself.
    • Competition
      • Intra-specific Competiton
        • Competition between individuals of the same species.
          • This type of competition is density dependent  since, as the population increases, a greater proportion of the population fails to survive.
            • This has value to a population since organisms tend to produce more offspring than the habitat can support.
              • Those organisms that are best adapted have a better chance of survival.
      • Inter-specific competiton
        • Competition between individuals of different species.
          • Each species occupies a particular place or NICHE, in an ecosystem.
            • This is not only the particular physical space it occupies but also the role it carries  out within the community.
              • In the long term, two species cannot occupy the same niche in a specific habitat.

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