1. Chapter 4: Population Ecology
Section 4.1: Population Dynamics
Section 4.2: Human Population

2. Graphing population growth isn’t like graphing the amount you get paid at a job or how many averages pages you can read in a book per hour
Linear Line

3. Graphing population will display a J-shaped curve. WHY?
This illustrates Exponential Population Growth

4. Exponential Growth Model
Exponential growth means that as a population gets larger, it also grows faster.
All populations grow exponentially until
some Limiting Factor slows the population’s
growth.

5. Logistic Growth Model
The population’s growth slows or stops following exponential growth, at the population’s Carrying Capacity.

6. Until the Industrial Revolution in the 1800s, human population growth was relatively slow.
During the Industrial Revolution, a sharp increase in human population growth began.
Today the Earth has reached a population of over 7 billion people
This is double the population of 1965

7. Carrying Capacity
The maximum number of individuals in a species that an environment can support for an indefinite period of time
Carrying capacity is limited by the energy, water, oxygen, and nutrients available (limiting factors)

8. Population-Limiting Factors
There are two categories of limiting factors
Density-independent factors
Density-dependent factors.

9. Density-Independent Factors
Any factor in the environment that does not depend on the number of members in a population per unit area
Weather events
Fire
Human alterations of the landscape
Air, land, and water pollution

10. Density-Dependent Factors
Any factor in the environment that depends on the number of members in a population per unit area
Biotic factors
Disease
Competition
Parasites

11. Population Ranges
A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded region.
Common dolphin
Pupfish

12. Human Population Growth
Demography = the study of human population size, density, distribution, movement, and birth and death rates is.

13. Birthrate – Death rate = Population Growth Rate (PGR)
A population stops increasing when the number of births is less than the number of deaths or when emigration exceeds immigration.
Births < deaths
Emigration > immigration
To calculate a country’s population growth rate:
Birthrate – Death rate = Population Growth Rate (PGR)

14. Zero Population Growth
Zero population growth (ZPG) occurs when the birthrate equals the death rate.
The age structure eventually should be more balanced with numbers at pre-reproductive, reproductive, and post-reproductive ages being approximately equal.

15. Age Structure
A population’s age structure is the number of males and females in each of three age groups:
Pre-reproductive Stage, Reproductive Stage, and Post-reproductive Stage.

16. Comparing Age Structures
Replacement occurs when a couple has only two children.
If there is an average of more than two children born to each couple, the population will grow.
A graph of the number of individuals of each age can show if the population is stable, growing or declining.
A growing population will have a pyramid shaped age structure graph

17. Increasing Population Decreasing Population

18. Stable Population

19. Human Population Growth Rate
Although the human population is still growing, the rate of its growth has slowed
Because of the rapid increase in the human population, there are concerns that the human population may someday reach its carrying capacity

20. Trends in Human Population Growth
Population trends can be altered by events such as disease, war, & zombies.
Human population
growth is not the same in all countries.

21. The more-developed countries have modest population growth rates due largely to decreased birthrates. WHY?
The less-developed countries have higher population growth rates because birthrates remain high. WHY?