1. Modeling Human Population Growth
Chapter 7
Modeling Human Population Growth

2. Essential Vocabulary Model Physical model Conceptual model
Mathematical model
Computer model
Birth rate
Death rate
Immigration
Emigration
Ecology
Population dynamics
Fertility Rate
Carrying capacity
Population density
Growth Rate
Predator-Prey Relationship

3. Essential Vocabulary Population curve Linear growth Exponential growth
J-curve
S-curve
Population crash

4. Activity 7.1: What is a model?
A representation of a system or its components
Example: macaroni noodles
represented otters in the
population estimation lab

5. Types of models: Physical Model Conceptual Model Mathematical Model
Computer Model

6. Types of models: Physical Model 3-D representation of a system.
Shows physical relationships between components of the system.
EX: Model car, or model of an atom

7. Physical Model:

8. Physical Model:
B-52 Model Plane

9. Types of models: Conceptual Model-
A diagram or pictorial representation of the components of a system
EX:
Food webs
Energy flow diagram

10. Conceptual Model

11. Conceptual models
Periodic table
Maps
Family trees

13. Types of models: Mathematical Model-
A Quantitative description of the relationship between multiple variables
Usually expressed as an equation
EX:
Final Population = [(birth rate – death rate) x initial pop.] + initial pop.

14. Mathematical models

15. Types of models: Computer Model
A computer-generated representation of a system.
Rapid calculations
Rapid manipulation of mathematical variables.
A form of mathematical model
EX:
World population projections
Weather forecasting

16. Activity 7.3: Changing Populations
Ecology
Branch of life science
Study of interactions among organisms and their surroundings.

17. Changing Populations Population Dynamics
Study of factors that cause population change over time.
Factors include: Birth Rate / Death Rate
Immigration / Emigration

18. Changing Populations Birth rate Death rate
# of births / year / 1,000 organisms
Death rate
# of deaths / year / 1,000 organisms

19. Changing Populations U.S. Statistics:
Birth rate = 13.9
Death rate = 8.2
In 1900, the death rate was !
Why has the death rate decreased dramatically since 1900?

20. Why has the U.S. death rate decreased significantly since 1900?
Science & Technology:
Medical equipment
Vaccines, Antibiotics
Water treatment facilities
Sewage/ waste treatment facilities

21. Changing Populations Fertility Rate RATIO btwn births & adult females
in a specific population at a particular time.

22. Changing Populations Predator-Prey Relationship
A relationship between two species of organisms in which one is a food source for the other.

23. Changing Populations Immigration Emigration
Movement of organisms INTO an ecosystem
Emigration
Movement of organisms OUT of an ecosystem

24. Changing Populations Growth Rate
Relative change in the value of a variable.
Final Population = POPinitial
+ Births + Immigration
- Deaths - Emigration
Growth Rate = (POPfinal - POPinitial ) / POPInitial

25. Changing Populations Carrying Capacity
The maximum population an ecosystem can support.
carrying capacity factors:
Availability of: living space, food, climate

26. Changing Populations Population density
The total number of organisms of a species in the same ecosystem at the same time.

27. How is population density calculated?
Pop density = # organisms / total area
EX: # of people / square mile
# of organisms / km2

28. Which regions of the world have the highest population density?
Regions with highest population-
do not always have the highest population density. WHY?
LAND AREA is an important variable in calculating population densities

29. Nevada Population Density

30. Las Vegas Valley Population Growth

33. Population Density China 1.3 Billion People 136 people / sq mile Japan
28 Million people
338 people / sq mile

36. Ch 8: Population Dynamics
Population curves can help predict future population changes
Conditions that affect population growth:
carrying capacity factors:
Availability of: living space, food, climate
birth rate, death rate, migration

37. Graphing Population Curves:
plot all data points and connect them.
Do NOT make a line of best fit.
line of best fit shows an “AVERAGE” of data points, not a linear growth pattern.

38. Population Curves

39. What do population graphs look like?
8.1
What do population graphs look like?
Negative growth rate – the population is decreasing
Positive growth rate – the population is increasing
Linear Exponential
Population size stays the same

40. Linear Curves
Steady population increase by the same amount over regular time intervals (years)
y = 2x
y is population size
x is time

42. Exponential Population Growth
J-curve
Rapid Growth rate
y=2x

45. Exponential Growth: Exponential population curves
cannot continue upward indefinitely
Exponential population growth eventually slows:
usually resulting in the formation of an:
S curve

46. S - Curve exponential (rapid) growth followed by a growth slow down
Eventual leveling off (flattening)
Usually when the population reaches its carrying capacity

48. Population CRASH
Rapid Decline in Population:

50. Causes of Population Crash:
Communicable, Infectious Disease
Catastrophic Events
hurricane, earthquake, tsunami, volcano
Loss of productivity in first trophic level
loss of topsoil in an agricultural area