1. Ecosystem Interactions
Why can’t everybody just get along…

2. Island of Surtsey
Born on November 14, 1963 from a volcano near Iceland
Brand new ecosystem; intensively studied
United Nations World Heritage Site

3. Competition
Interaction between 2 or more organisms fighting for the same resource in a given area
Can be within species or between different species

4. Predation One organism eats another for food
Prey are usually well adapted to avoid predators (speed, quills, sense of smell, aggressive displays, mimicry, etc.)

5. Equilibrium
Populations stay the same over time (number of births = number of deaths)
Animals have adjusted to stresses put on them

6. Carrying Capacity
The maximum number of individuals of a species that can be supported indefinitely by an ecosystem
Different number for each species

7. Oh Deer!

8. Human Population Histogram
Do you think human population will exceed the Earth’s CARRYING CAPACITY?
What factors will limit our population growth?

9. Limiting Factors
An environmental factor that prevents an increase in the number of organisms in a population
Abiotic: sunlight, temp, etc.
Biotic: disease, predators, etc.

10. “The Law of the Minimum”:
The nutrient in least supply is the one that limits growth.
“The Law of Tolerance”:
An organism can survive within (tolerate) a certain range of an abiotic factor
(eg. Cold)

11. Population Density:
The Number of organisms in an area

12. Density-Independent Factors:
Affect members of a population regardless of population density. Ex: Fire, flood
Density-Dependent Factors:
Affect populations because of the density of the population. Ex: Food supply, water quality, disease spread

13. Population Factors
Natality: The number of offspring (babies) of species born in one year.
Mortality: The number of individuals of a species that die in one year.
Immigration: The number of individuals of a species moving into an existing population.
Emigration: The number of individuals of a species moving out of an existing population

14. Open vs. Closed Populations
Open Population:
- All 4 factors [natality, immigration, etc.] are at work on the population.
Closed Population:
Only mortality and natality are at work.
Population Growth=
(natality + immigration) - (deaths + emigration)

15. Open vs. Closed Populations
Jackson Park would be an example of an open population – animals can come and go
What would be an example of a closed population?
Zoo - farm field
Fenced yard - wildlife preserve

16. Know your Relationships!
P 54…copy definitions!
Competition
Predation
Mutualism
Parasitism
Commensalism