1. Warm-Up Fri 4/7
If the producers have 10,000 J of energy, how much energy is contained in the highest trophic level?
What is the name of this type of pyramid?
Which organism would be the most affected by toxic chemicals in the water? EXPLAIN.

2. To be successful today…
Pick up warm-up sheet
**If you need to make-up a test, you must do so by tomorrow AM. **
3) STAAR Review in Auditorium TODAY!
BYOD Color of the day is Phones are in put away in backpacks

3. Warm-up Mon 4/10
How would the populations of rabbits and hawks would change if a forest fire destroyed all the grass?
What type of disturbance is this?

4. Population Ecology

5. Population Ecology Deals with 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.

6. 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.

7. Sea Otter Example

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

10. How Populations Change Over Time
Three factors control how a population changes over time:
Number of births
Number of deaths
Number of individuals that enter (emigration) or leave (immigration) an ecosystem

11. 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.

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

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

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

15. 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

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

17. Describe these growth curves

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

19. What Limits the size of a population?

20. 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

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

22. 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

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

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