1. Community
A group of different populations that lives in the same geographic area

2. Community Interactions
Interactions between organisms have a huge impact on ecosystems.

3. Community Interactions
Types of interactions:
Competition—when organisms attempt to use a resource in the same place at the same time.
Competitive exclusion principle—no two species occupy the same niche in the same habitat.
Predation—an interaction where one organism captures and feeds on another organism

4. More interactions
Symbiosis—a relationship in which two species live closely together.
Usually one species lives on or inside of another.
One species always benefits and other can be harmed, helped, or have no effect.

5. Types of Symbiosis
Mutualism—a symbiotic relationship in which both species benefit. Ex: Flowers and the insects that pollinate them.
Commensalism—a symbiotic relationship in which one species benefits and the other is unaffected. Ex: barnacles on a whale
Parasitism—a symbiotic relationship where one species benefits and the other is harmed. Ex: Fleas, ticks, tapeworms and their hosts.

6. Types of Symbiosis .
The acacia tree and Pseudomyrmex ants are an example of mutualism

7. Types of Symbiosis .
An epiphyte plant is an example of commensalism

8. Types of Symbiosis .
A tapeworm is an example of a parasite

9. Ecological Succession
Ecological Succession—The series of predictable changes that occurs in a community over time.
As an ecosystem changes, older species gradually die out and new species move in.

10. Types of Succession
Primary Succession—When succession occurs on surfaces where no soil exists. Ex: after a volcanic eruption builds a new island or covers land with lava rock.
Secondary Succession—When a disturbance changes an ecosystem without removing the soil. Ex: a forest after a fire.

11. Succession
Climax Community—an older, established community that is no longer changing (as much)

12. Populations Population Density—The number of individuals per unit area
Ex: number of dandelions per m2

13. Population Growth Several factors affect population size:
Births— # of organisms born
Deaths— # of organisms that die
Immigration—The movement of organisms into a population
Emigration—The movement of organisms out of a population

14. Exponential Growth
Unrestricted populations of organisms experience exponential growth.
Must have unlimited resources

15. Exponential Growth Graph

16. Logistic growth
As resources become less available, population growth slows or stops (birth rate=death rate) This is called leveling off.
Carrying capacity—The maximum number of organisms that the environment can support

17. Logistic growth graph

18. Limiting factors
Limiting factor—a factor that causes population growth to decrease.

19. Density-Dependent factors
Density-Dependent factors—limiting factors whose effects increase as the size of the population increases
Ex: Competition, predation, parasitism, disease

20. Density-Independent factors
Density-Independent factors—Limiting factors that affect all populations in similar ways, regardless of population size and density
Ex: Natural disasters, seasonal cycles, certain human activities

21. Human populations
Demography—The scientific study of human populations

23. Exponential Growth in our human population
Since the industrial revolution of the 1800s the human population has been experiencing exponential growth.

24. Effects of increased growth
If the human population continues to grow at an exponential rate this could cause:
Starvation and death for millions
Some countries to set limits on birth rates

25. Slowing population growth
Human population growth can be slowed by:
Global epidemics (influenza, HIV, etc.)
Limiting birth rates

26. Biodiversity
Biodiversity—the total variety of organisms in the biosphere.
It is important to preserve biodiversity for a variety of reasons (food webs, new medicine, etc.)

27. Maintaining biodiversity
Humans can help maintain biodiversity by:
Enforcing the Endangered Species Act
Making laws protecting the wilderness (including rainforests)

28. Destroying Biodiversity
Humans can destroy biodiversity by:
Habitat destruction - *** Keystone species may leave/die so those below it on food chain are effected
Introducing invasive species
(ex: Zebra mussels in Great Lakes, rabbits in Australia, etc.)

29. The Greenhouse effect The Greenhouse effect—
Water vapor and greenhouse gases (CO2, methane, etc.) trap heat from the sun in our atmosphere. This keeps Earth warmer, like the glass panels of a greenhouse.

30. Global Warming
Global Warming—An increase in greenhouse gases which increases the amount of heat trapped in Earth’s atmosphere. ADD; Specifically CO2

31. Human activities causing global warming
Burning fossil fuels and cutting down the rainforests are increasing greenhouse gases (especially CO2), which is most likely causing global warming.

32. Temperatures rise  glaciers melt  sea levels rise
Solutions: Burn less fossil fuels alternative energy sources

33. Air Pollution
The quality of our air is important to our health. Burning fossil fuels and factory emissions being released into the air contribute to air pollution.