1. What Shapes an Ecosystem
4-2

2. Biotic and Abiotic Factors
Biotic Factors – the biological influences on organisms within an ecosystem
Abiotic Factors – the physical or nonliving factors that shape an ecosytem
Together biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives

3. Habitat
Habitat – is the area where an organism lives

4. Niche
Niche – is the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions
For example the niche of owl is all of the following biotic and abiotic factors:
Lives in trees
Feeds at night
Feeds on mice
Lives in cool climate
Which of the following above are biotic and abiotic?

5. Niche No two species can share the same niche in the same habitat
Different species can occupy niches that are very similar

6. Niche Example What is the Niche in Baseball?
What is the Niche of different local businesses?

7. Community Interactions
Competition occurs when organisms compete for a resource
Resource – is any necessity of life, such as water, nutrients, light, food, or space
Direct competition results in a winner and a loser (the loser doesn’t survive)
Competitive Exclusion Principle – state that no two species can occupy the same niche in the same habitat at the same time

9. Community Interactions
Predation – where one organism captures and feeds on another organism (lion and gazelle)
Symbiosis – any relationship in which two species live closely together (3 forms as follows)
Mutualism – both species benefit from the relationship (ex. bee and flower)
Commensalism – one member of the association benefits and the other is neither helped or harmed (ex. barnacles attached to a whale)
Parasitism – one organism lives on or inside another organism and harms it (ex. tick and dog)
Can you think of any other example for all of these?

10. Ecological Succession
Ecosystems are constantly changing in response to natural and human disturbances
As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community
This series of predictable changes that occurs in a community over time is called Ecological Succession

11. Primary Succession
Primary succession is the first time life appears on a new surface of land
Occurs after volcanic activity or melting of glaciers
When primary succession begins there is no soil, just ash and rock
The first species to populate the areas are called Pioneer Species

12. Primary Succession The primary species on volcanic rock are lichen
Lichen is made up of a algae and fungus that can grow on rock
The lichen grow on the rock and break it down
When the lichen die they add organic material to help form soil for plants to grow on

13. Secondary Succession
Disturbances such as Fire or farming can alter an ecosystem
When the disturbance is over, community interactions tend to restore the ecosystem to its original condition through Secondary Succession
For ex. Lightning in woodlands causes a fire burning the woodlands down, the fire also causes pine cones to explode and spread their seed to allow the forest to re-grow once the disaster is over

15. Homework
Read 4-2
P. 97 Q 1-6