5 populations

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5 populations

  1. 1. Chapter 5 Populations
  2. 2. 5.1 How Populations Grow <ul><li>3 Important Characteristics of a population: </li></ul><ul><ul><li>Geographic Distribution </li></ul></ul><ul><ul><li>Density </li></ul></ul><ul><ul><li>Growth Rate </li></ul></ul>
  3. 3. Population Density <ul><li>The number of individuals per unit area </li></ul><ul><ul><li>Example: Cactus in Desert vs. Other plants </li></ul></ul>
  4. 4. Population Growth <ul><li>3 factors affect population growth: </li></ul><ul><ul><li>Number of Births </li></ul></ul><ul><ul><li>Number of Deaths </li></ul></ul><ul><ul><li>Number of individuals that enter or leave a certain area </li></ul></ul>
  5. 5. Population Growth <ul><li>Population growth can be positive or negative. </li></ul><ul><li>Example: </li></ul><ul><ul><li>Penguins </li></ul></ul>
  6. 6. Example: Penguins <ul><li>At the beginning of the year there were 1200 penguins and 1600 at the end of the year. </li></ul><ul><li>What was the population growth? </li></ul><ul><ul><li>An increase of 400 penguins. </li></ul></ul>
  7. 7. Example: Penguins <ul><li>Suppose 250 chicks died during the year. </li></ul><ul><li>What is the population growth? </li></ul><ul><ul><li>A net increase of 150 penguins </li></ul></ul>
  8. 8. Example: Penguin <ul><li>Suppose that 200 adults died during the year. </li></ul><ul><li>What is the populations growth? </li></ul><ul><ul><li>A net decrease- or negative growth- of 50 penguins. </li></ul></ul>
  9. 9. Population Growth <ul><li>Immigration: </li></ul><ul><ul><li>Movement into an area </li></ul></ul><ul><ul><li>This can increase a populations growth </li></ul></ul>
  10. 10. Population Growth <ul><li>Emigration: </li></ul><ul><ul><li>Movement out of an area </li></ul></ul><ul><ul><li>This can decrease the populations growth </li></ul></ul><ul><ul><li>Food shortages can lead to emigration </li></ul></ul>
  11. 11. Exponential Growth <ul><li>Individuals in a population reproduce at a constant rate </li></ul><ul><li>At first the growth is slow, then it becomes larger and larger </li></ul>
  12. 12. Logistic Growth <ul><li>Population’s growth slows or stops following a period of exponential growth </li></ul><ul><li>Less resources available, less growth </li></ul>
  13. 13. Logistic Growth <ul><li>Follows a general S-shaped curve </li></ul><ul><li>Carrying Capacity: Largest number of individuals an </li></ul><ul><li>environment can </li></ul><ul><li>support </li></ul>
  14. 14. Analyzing Data Activity <ul><li>Turn to page 123 </li></ul><ul><li>Follow the directions and answer the questions that deal with graphing for Exponential Growth and Logistic Growth </li></ul>
  15. 15. 5.2 Limits to Growth <ul><li>Limiting Factor: </li></ul><ul><ul><li>Factors that cause a population growth to decrease. </li></ul></ul><ul><ul><li>Examples: </li></ul></ul><ul><ul><ul><li>Competition, Predation, Parasitism and disease, Drought and other climate extremes, and Human Disturbances </li></ul></ul></ul>
  16. 16. Density Dependent Factors <ul><li>Limiting factor that depends on population size. </li></ul><ul><li>Includes: </li></ul><ul><ul><li>Competition </li></ul></ul><ul><ul><li>Predation </li></ul></ul><ul><ul><li>Parasitism and </li></ul></ul><ul><ul><li>Disease </li></ul></ul>
  17. 17. Density Independent Factors <ul><li>Limiting factor that does not depend on population size. </li></ul><ul><li>Include: </li></ul><ul><ul><li>Unusual Weather </li></ul></ul><ul><ul><li>Natural Disasters </li></ul></ul><ul><ul><li>Seasonal Cycles </li></ul></ul><ul><ul><li>Certain Human Factors </li></ul></ul>
  18. 18. 5.3 Human Population Growth <ul><li>Human population tends to increase with time. </li></ul><ul><li>Patterns of Population Growth: </li></ul><ul><ul><li>Demographic Transition </li></ul></ul><ul><ul><li>Age Structure </li></ul></ul>
  19. 19. Demographic Transition <ul><li>Change in a population from high birth and death rates to low birth and death rates. </li></ul><ul><ul><li>What are some reasons why some countries have a high growth rate and others do not? </li></ul></ul><ul><ul><ul><li>Nutrition </li></ul></ul></ul><ul><ul><ul><li>Sanitation </li></ul></ul></ul><ul><ul><ul><li>Medicine </li></ul></ul></ul>
  20. 20. Age Structure <ul><li>Population growth depends on how many people make up different ages in a population. </li></ul>
  21. 21. Age Structure Diagram

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