Population Change

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