1. Population Ecology

2. Population Ecology
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. Population Ecology
Natural and Human disturbances can lead to a change in a population over time.
If the number of species in one community changes it will ultimately lead the changes in the number of species in all other communities in the ecosystem.

4. Sea Otter Example

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

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. Limiting Factors
Limiting factors are factors that cause population growth to slow or stop
Ex. food, water, space, sunlight

10. Growth under ideal conditions
Populations can grow exponentially
Unlimited food and space
What are the limiting factors?

11. When resources become limited
Growth slows
Populations stay at the carrying capacity
This is good for the environment

12. Other Growth Curves
Too many births “overshoots” the carrying capacity and leads to population crash
Predator & prey populations keep populations under the carrying capacity

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

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

15. Swamp Rats in California

16. https://www. mysanantonio

17. What Limits the size of a population?

18. Density dependent limiting factors
Depends on population size
Operates most strongly on large populations
Competition for resources — food, water, space, sunlight
Competition within species or with different species

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

20. Practice
Classify each of the following as either density-dependent or density-independent.
Intense heat wave
Half of the forest trees are cut down
3. Sudden blizzard
4. Overpopulation of an organism