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Population Change

Chapter 8. Population Change. Principles of Population Ecology. Population ecologists ask: 1) How many are in the population? 2) Are its numbers increasing / decreasing? 3) What is its pattern of reproduction? 4) What is its pattern of mortality?. Principles of Population Ecology.

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Population Change

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  1. Chapter 8 Population Change

  2. Principles of Population Ecology • Population ecologists ask: • 1) How many are in the population? • 2) Are its numbers increasing / decreasing? • 3) What is its pattern of reproduction? • 4) What is its pattern of mortality?

  3. Principles of Population Ecology 20 / 25 m2 20 / 100 m2 • Population Density: • Not enough to know just how many. • Need to know per unit area.

  4. Principles of Population Ecology • How Do Populations Change in Size? • On a global scale (closed system):

  5. Principles of Population Ecology • How Do Populations Change in Size? • On a local scale (open system):

  6. Principles of Population Ecology Death rate Growth rate Birth rate • How Do Populations Change in Size? • Global scale: r = b – d

  7. Principles of Population Ecology Death rate Growth rate Emigration rate Birth rate Immigration rate • How Do Populations Change in Size? • Local scale: r = (b – d) + (i – e)

  8. Principles of Population Ecology • Maximum Population Growth- • under ideal conditions = intrinsic rate of increase J-shaped curve (exponential growth)

  9. Principles of Population Ecology • Environmental Resistance- • Exponential growth cannot occur forever. • What factors prevent it from doing so? S-shaped curve (logistic growth)

  10. Principles of Population Ecology • Overshooting the carrying capacity can lead to a population crash.

  11. Reproductive Strategies K-selected vs. high growth rate slow growth rate small body size large body size early maturity late maturity short life span long life span large broods small broods little / no parental care high parental care • Life History Strategies r-selected

  12. Reproductive Strategies • Survivorship

  13. Factors that Affect Population Size • Density-Dependent Factors- • Factors that influence population growth when its density is high. • Predation, competition, disease.

  14. Factors that Affect Population Size • Density-Dependence and Boom-or-Bust Population Cycles

  15. Factors that Affect Population Size • Case-in-Point: Predatory Prey Dynamics on Isle Royale

  16. Factors that Affect Population Size • Density-Independent Factors- • Regardless of population density, influences population growth. • Weather, fire.

  17. The Human Population • Human population size

  18. The Human Population • Current Population Numbers • In 2004 = ~6.4 billion • Check out: • http://www.census.gov/main/www/popclock.html

  19. The Human Population • Current Population Numbers • Rapid growth primarily due to drop in death rates

  20. The Human Population • Projecting Future Population Numbers • When will zero population growth occur?

  21. Demographics of Countries • Most Populous Countries

  22. Demographics of Countries • Developed vs. Developing Countries Demographics

  23. Demographics of Countries • Developed vs. Developing Countries Demographics

  24. Demographics of Countries • Demographic Stages

  25. Demographics of Countries • Age Structure of Countries • Generalized Age Structure

  26. Demographics of Countries • Examples:

  27. Demographics of Countries • Examples:

  28. Demographics of Countries • Examples:

  29. Demographics of Countries • Population Under Age 15:

  30. Demographics of the US • Case-in-Point: US Immigration

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