Population Change

1
Population Change
Chapter 8
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

• 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

• How Do Populations Change in Size?
• Global scale

r b d
7
Principles of Population Ecology

• 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

• 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 Predator Prey Dynamics on Isle
  Royale. Which population controls the other?

16
Factors that Affect Population Size

• Density-Independent Factors-
• Regardless of population density, influences
  population growth.
• Weather, fire, earthquake.

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 link to census

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