1. Population Ecology

2. Population Ecology Factors that affect population size:
Natural and Human Disturbances play a role in the shaping an ecosystem.
Natural Disturbances – fire, tornadoes, hurricanes, etc.
Human Disturbances – deforestation, destroying of habitats.

3. Sea Otter Example

4. Predict what happens to sea urchin and kelp when sea otters are removed

6. How Populations Change Over Time
Three factors control how a population changes over time:
# of births
# of deaths
# of individuals that migrate

7. Carrying Capacity
Carrying Capacity - The largest number of individuals that the environment can support When an ecosystem reaches its carrying capacity the food web begins to change drastically.

8. Predict what happens when a population “overshoots” its carrying capacity

9. Population growth
Populations can grow in 2 different ways:

10. 1) Exponential growth
Growth under ideal conditions at an ever increasing rate
Abundant space, food, protection
J-shape curve

11. 2) Logistic growth
Growth when resources become less available and growth slows
S-shape curve
NOTE: even when population growth stops it still rises and falls somewhat
AKA Carrying Capacity Graph

12. Other Growth Curves Boom and Bust
Exponential Growth that leads to population crash
Predator-Prey
Predator & prey populations increase and decrease together

13. Describe these growth curves

14. Limiting Factors Limiting factors cause population growth to decrease.
Can be dependent on the species in the ecosystem or completely unpredictable like natural disasters.

15. What Limits the size of a population?

17. Density dependent limiting factors
Depends on population size ( affects large populations)
Competition for resources
Competition within species or with different species

18. Density-Independent limiting factors
Affects all populations, regardless population size
Population crashes
Causes: human activity, weather, and natural disasters

19. Classify as either density-dependent or density-independent.
Practice
Classify as either density-dependent or density-independent.
Intense heat wave
Half of the forest trees are cut down
3. Sudden blizzard
Overpopulation of an organism
Hospital MRSA outbreak

20. What happens when an invasive species is introduced into an established ecosystem?

21. How many raccoons can live in this forest?

22. Not native to ecosystem
No natural predators
Can outcompete native species for resources
Examples: Kudzu vine, Chinaberry trees