1. Populations and Growth

2. KEY CONCEPT Populations grow in predictable patterns.

3. Population Dispersion

4. Survivorship Curves Type I Few offspring Low infant mortality
Parental care of young
Most survive until old age
Large mammals, including humans

5. Survivorship Curves Type II
Equal chance of living or dying throughout the lifetime
Birds, reptiles, small mammals

6. Survivorship Curves Type III High infant mortality rate Many offspring
No parental care
Invertebrates, fish, amphibians, and plants

7. Changes in Population Size
Growth factors
Immigration: individuals moving into a population
Births
Shrinking factors
Emigration: individuals moving out of a population
Deaths

8. Changes in a population’s size are determined by immigration, births, emigration, and deaths.
The size of a population is always changing.
Four factors affect the size of a population.
immigration
births
emigration
deaths

9. Population growth is based on available resources.
Exponential growth is a rapid population increase due to an abundance of resources.

10. Exponential Growth Early phase of growth
High availability of resources
Little competition
Little predation

11. Logistic growth is due to a population facing limited resources.

12. Logistic Growth Limits on growth appear Competition for resources
Predation
Parasitism
Illness

13. Carrying capacity is the maximum number of individuals in a population that the environment can support.
A population crash is a dramatic decline in the size of a population over a short period of time.

14. Ecological factors limit population growth.
A limiting factor is something that keeps the size of a population down.
Density-dependent limiting factors are affected by the number of individuals in a given area.

15. Density-dependent limiting factors are affected by the number of individuals in a given area.
predation
competition
parasitism and disease

16. Density-independent limiting factors limit a population’s growth regardless of the density.
unusual weather
natural disasters
human activities

17. Human Population Growth
Are humans in exponential or logistic growth?

18. U.S. Population Density - 2000
People per square mile
0-1 (white) (green) (blue)
1-4 (yellow) (teal) ,995 (dark blue)
5-9 (yellow-green) (dark teal)