population growth

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population growth
2012-04-25 14:32:35
population growth

population growth
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  1. population
    • consists of all the members of a particular species that live within an ecosystem
    • Freshman at QU- living in same place (QU). The dorm= community
  2. community
    • a group of interacting populations
    • Dorm
  3. Biosphere
    • is the enormous ecosystem that encompasses all of Earths habitable surface

  4. Two opposing forces determine birth and death rates
    biotic potential, eviormental resistance

    • In nature, the interaction between biotic potential and environmental resistance usually results in a balance between the size of a population and the resources available to support it
  5. Biotic potential
    • : the theoretical maximum rate at which a population could increase, assuming a maximum birth rate and minimal death rate

    How long a person can live= 100 yrs, can have maximum of 15 children on average
  6. Environmental resistance
    • refers to the curbs on population growth that are set by the living and nonliving environment

  7. Population growth is a function of the birth rate, the death rate, and population size
    • growth rate (r) = rate of natural increase,
    • (doesnt account for immigration/emigration)
    • r (growth rate) = b (birth rate) – d (death rate)
    • Example for a population
    • r = 0.15 (b) – 0.05 (d) = 0.1 = 10% per year
  8. J-curve exponential growth
    • If births exceed deaths by a constant percentage, population growth produces a J curve- keeps increasing

    • eventually stops and decreases : resources become limited, disease, climate change, competition,
  9. boom and bust poulation cycles
    algea= bloom rapidly and use all resources and all die (bust)
  10. complex factors produce four year boom and bust cycles for small rodents, such as lemmings
    lemming populations may grow until lack of food, large migration,a nd predators and starvation cause sudden mortality

    mimick each other- jump off cliff and all die