1. Bullet 2: Fluctuations in Population Growth
MT 3: Ecology

2. Review of Population:
Group of the same species that live in the same location

3. What are significant changes that can happen in an ecosystem?
Pair-Share:
Turn to partner and discuss for 30 seconds.

4. Types of Changes Natural Events: Human Interactions:
Abiotic Changes: Biotic Changes:

5. What specific factors cause a population's size to change?
Birth
Death
Immigration
Emigration

6. How does each factor cause a population to change?
Increase
Birth
Death
Immigration
Emigration
decrease
Increase
decrease

7. Increase in population
Birth
Increase
Immigration

8. Decrease in population
Death
Decrease
Emigration

9. Types of population growth
1. Exponential growth: occurs when resources are unlimited
2. Logistic growth: occurs when resources are limited

10. Exponential Growth
Occurs under perfect conditions – unlimited resources, no predators
In nature, does not occur very long
Ex: 2, 4, 8, 16, 32, 64, 132, 264

11. Exponential Growth

12. Logistic Growth
More realistic in nature because of limited resources (food, shelter, mates)
S-shaped graph. Population grows until its carrying capacity is reached.

13. Logistic Growth

14. Carrying Capacity
The number of individuals in a population that can be supported by its environment.
Based on resources (food, shelter, mates) in the environment.
When a population reaches carrying capacity, the population has a net growth rate of zero.

15. Question: In nature, do you think most populations have the same number of individuals all year long?
No, most populations fluctuate in size.

16. Question: What season would you predict that many populations reproduce? Defend your answer.
Spring: moderate temperatures, adequate water supply, abundance of grass/plants (producers) so most consumers have something to eat