1. Biology
Ch. 5
Populations

2. I. Population Dynamics
- Biological processes constantly influence a population’s density, dispersion, and growth rate.
Tent Caterpillars

3. A. Population Characteristics
1. Population Density
- number of organisms per unit area

4. 2. Spatial Distribution - uniform, clumped, random Clumped Uniform

5. 3. Population Range
- depends on the species’ adaptations to biotic and abiotic factors
Range of the Cougar
Range of the Olympic Marmot

6. 4. Population Growth Rate
- balance between birth and immigration and death and emigration
Births
Immigration
Population Size
Emigration
Deaths
Deaths and emigration remove individuals from a population.
Births and immigration add individuals to a population.

7. B. Exponential Growth
- shows an increasing growth rate - under ideal condition with unlimited resources

8. B. Exponential Growth - results in population explosion
1900
1920
1940
1960
1980
Year
2,000
4,000
6,000
8,000
Elephant Population
Exponential Growth in the African Elephant Population of Kruger National Park, South Africa

9. B. Exponential Growth

10. Paramecium population
C. Logistic Growth
- population growth levels off at carrying capacity (S-shaped curve)
1,000
800
600
400
200
180
150
120 90 60 30
Time (days) 5 10 15
160
140 80
100 40 20
Number of Paramecium/ml
Number of Daphnia/50 ml
Paramecium population
Daphnia population

11. Effects of Exceeding Carrying Capacity
reindeer introduced
reindeer
reindeer survived
food (lichens) overgrazed
St. Paul Island, Alaska
Effects of Exceeding Carrying Capacity
Figure: 38.6a
Title:
The effects of exceeding carrying capacity
Caption:
Exceeding carrying capacity can damage an ecosystem, reducing its ability to support the population. In 1911, 25 reindeer were introduced onto one of the Pribilof Islands (St. Paul) in the Bering Sea off Alaska. Food was plentiful, and the reindeer encountered no predators on the island. The herd grew exponentially (note the initial J shape) until it reached 2000 reindeer in At this point, the small island was seriously overgrazed, food was scarce, and the population declined dramatically. By 1950, only eight reindeer survived.

12. D. Reproductive Patterns
R-strategists
K-Strategists

13. 1. R-Strategists
- adapted to unstable environments - short life spans - produce many offspring
Chum Salmon
Mayfly adults emerging to mate.

14. 1. R-Strategists
- adapted to unstable environments - short life spans - produce many offspring
Dandelion
Chum Salmon

15. 2. K-Strategists
- adapted to more stable environments - long life spans - produce fewer offspring

16. II. Limits to Growth A. Limiting Factors
- factors that control population growth
Competition
Natural
Disaster
Population
Size
Predation
Unusual
Weather
Parasitism
and Disease

17. II. Limits to Growth A. Limiting Factors - determine carrying capacity
Competition
Natural
Disaster
Population
Size
Predation
Unusual
Weather
Parasitism
and Disease

18. 1. Density-Dependent Factors
- affect populations more as density increases - competition

19. 1. Density-Dependent Factors
- affect populations more as density increases - competition, predation
Year
1850
1875
1900
1925 40 80
120
160 3 6 9
Lynx population size (thousands)
Hare population size (thousands)
Lynx
Snowshoe hare
Snowshoe Hare and Lynx

20. 1. Density-Dependent Factors
- affect populations more as density increases - competition, predation, disease and parasites

21. 2. Density-Independent Factors
- affect populations regardless of density
Forest Fire
Tsunami
Tornado

22. III. Human Population Growth
8000 B.C.
4000 B.C.
3000 B.C.
2000 B.C.
1000 B.C.
1000 A.D.
The Plague
Human population (billions)
2000 A.D. 1 2 3 4 5 6
- Humans are undergoing a population explosion.

23. Human Population Growth
Human Population Clock

24. 1. For most of human existence, death rates were high.
A. Historical Overview
1. For most of human existence, death rates were high.
2. In 1800’s, death rate decreased due to technological advances.
- agricultural improvements
- advances in sanitation and medicine
- birth rates remained high
3. World population is ~7.5 billion.
- about 1 billion added every 12 years

25. - the study of population growth trends
B. Demography
- the study of population growth trends
1. Demographic Transition
- shift from high birth and death rates to low birth and death rate

26. Demographic Transition in Sweden and Mexico50 40 20 30 10
1750
1800
1850
1900
1950
2000
2050
Birth rate
Death rate
Year
Sweden
Mexico
Birth or death rate per 1,000 people

27. - the study of population growth trends
B. Demography
- the study of population growth trends
1. Demographic Transition
- shift from high birth and death rates to low birth and death rate
- U.S., Japan, and Europe have passed through the demographic transition.
- S. America, Africa, and Asia are passing through Stage II.
Human Population (millions)
Time (Years)

28. Human Population Growth Rate by Country

29. Rapid Growth Afghanistan
2. Age Structure and Population Growth
- Age structure diagrams are used to predict population growth trends.
Rapid Growth Afghanistan
Slow Growth United States
Decrease
Italy
Male
Female
Age 8 6 4 2
Percent of population
80–84
85
75–79
70–74
65–69
60–64
55–59
50–54
45–49
40–44
35–39
30–34
20–24
25–29
10–14
5–9
0–4
15–19

30. Age Structure Diagrams for Japan in 1950, 2005, and 2050

31. Population (Millions)
3. Future Population Growth
- As countries complete the demographic transition, population growth will begin to slow down.
Time (Years)
Population (Millions)

32. Ecological Footprint in Relation to Available Ecological Capacity16 14 12 10 8 6 4 2
New Zealand
Australia
Canada
Sweden
World
China
India
Available ecological capacity (ha per person)
Spain UK
Japan
Germany
Netherlands
Norway
USA
Ecological footprint (ha per person)

33. The
End

34. 3. Boom-and-Bust Population Cycle
- population greatly exceeds carrying capacity resulting in a population crash
Annual lake algal bloom
Conditions good: Boom Conditions bad: Bust