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Populations

Populations. Population- group of individuals of the same species occupying a given area Increase Birth Immigration Decrease Death Emmigration. Populations Change. Populations increase Birth rate > Death Rate Immigration > Emmigration Populations Decrease Birthrate < Death Rate

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Populations

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  1. Populations • Population- group of individuals of the same species occupying a given area • Increase • Birth • Immigration • Decrease • Death • Emmigration

  2. Populations Change • Populations increase • Birth rate > Death Rate • Immigration > Emmigration • Populations Decrease • Birthrate < Death Rate • Immigration <Emmigration

  3. Exponential Growth • r = Net Reproduction per individual • Growth = (r) x (N)umber of individuals • Ex: Bacteria: r = 100% per ½ hour • Ex: Humans: r = 2-5% /yr • Doubling Time- Length of time it takes for a population to double in size

  4. Exponential Growth

  5. Notes on Exponential Growth • The more of something there is, the more it can produce. • Population Growth Must be Limited • Limiting Factors • Food • Space • Predators • Disease • Polluted Environment

  6. Carrying Capacity (K) • Carrying Capacity (K)- Maximum number of individuals of a population that a given environment can sustain • This leads to Logistic Growth

  7. Overshooting K

  8. History of Human Population

  9. Poverty • The countries that have the highest population growth are the ones least capable of dealing with it. • In developing nations, children are still an asset, not a liability • In 1999, the richest 20% possessed 82 times the income of the poorest 20% • The richest 20% used 86% of the world’s resources, leaving 14% for the other 80%

  10. Demography • Demography (‘People’ ‘Measure’)- encompasses vital statistics about people, such as births, deaths, number of males and females, age structure, as well as total population size. • Age Structure- How many people of there are of various ages

  11. Fertility and Birth Rates • Fertility- Births per woman • Total Fertility Rate- number of children born to an average woman in a population during her entire reproductive life

  12. Zero Population Growth (ZPG) • Zero Population Growth (ZPG) occurs when births plus immigration in a population just equal deaths plus emigration • When infant mortality is high, total fertility rate needs to be about 4 or 5 to reach ZPG • When mortality is low, as in more highly developed countries, the rate needs to be about 2.1 to reach ZPG.

  13. Don’t Forget the Footprint

  14. Two Problems • Increasing Ecological Footprints in the rest of the world mean less resources and more poverty • Immigration to developed nations means more big Ecological Footprints and using more resources

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