1. How do communities change over time?
Population Growth
How do communities change over time?

2. Characteristics of Populations
Geographic distribution- describes the area inhabited by a population
Distribution density- the number of individuals per unit area
Growth rate- increase/decrease per unit time
Age Structure-how many people of different ages make up a given population

3. Population Growth Number of births (birth rate)
Number of deaths (death rate)
Movement into a population (immigration) and movement out of a population (emigration)
Examples:
↑ birth rate + ↓ death rate= ↑ pop. growth
↑ birth rate + ↑ death rate = ↔ pop. Growth
↑ immigration = ↑ pop. Growth
↑ emigration = ↓ pop. Growth
Immigration = emigration = ↔ pop. growth

4. Population growth
Populations will grow until they reach their biotic potential, unless they are limited by factors in the environment
This type of growth is known as a J-curve

5. Exponential Growth
Occurs when the individuals in a population reproduce at a constant rate
Under ideal conditions with unlimited resources

6. Fill It In …
Define “exponential growth”:

7. Population growth
Limiting factors, such as availability of food, water, and space establish a carrying capacity for populations
This type of growth is known as a S-curve.

8. Logistic Growth
Occurs when a population’s growth slows or stops following a period of exponential growth
As resources become less available, the growth of a population slows or stops

9. Fill It In …
List limiting factors for a population of dandelions:

10. Population growth
Carrying capacity is defined as the number of individuals an environment can support.

11. Population growth
Limiting factors in the environment help to maintain ecosystem stability by allowing populations to fluctuate around the carrying capacity.
This is called dynamic equilibrium.

12. Population growth
Density dependent factors have a greater effect on a population when there is a higher population density (the number of individuals in a given space).
For example, competition, predation, and the spread of infectious diseases are density-dependent factors.

13. Population growth
Density independent factors influence the size of a population regardless of its density.
For example, natural disasters such as forest fires are density independent factors.

14. Age Structure

15. Check Yourself! What kind of curve illustrates exponential growth?
What determines the carrying capacity of the environment?
List 3 examples of limiting factors.

16. Population growth
Succession is the idea that communities will replace other communities in a predictable, orderly way; this happens because every community alters the physical factors of the environment.
Ex. As trees grow, they produce shade.

17. Check Yourself!
What kind of curve illustrates exponential growth? J-CURVE
What determines the carrying capacity of the environment?
List 3 examples of limiting factors.

18. Check Yourself!
What kind of curve illustrates exponential growth? J-CURVE
What determines the carrying capacity of the environment? LIMITING FACTORS
List 3 examples of limiting factors.

19. Check Yourself!
What kind of curve illustrates exponential growth? J-CURVE
What determines the carrying capacity of the environment? LIMITING FACTORS
List 3 examples of limiting factors. FOOD, WATER, AND SPACE