1. What Is An Ecosystem?
An ecosystem is a community of living and non-living things that interact and work together.
An ecosystem includes the soil, atmosphere, heat and light from the sun, water, and living organisms.

2. Interactions in Nature
All of the organisms of one kind in an ecosystem are called a population. (Examples – frogs, insects, protists)
Populations interacting with each other form a community. (How do people Interact?)

3. Interactions With Nature
Another part of an ecosystem is the physical environment, which includes the sun, air, water, soil, and climate.
Populations can also interact with the physical environment.
Plants use sunlight, water, and soil nutrients
Fish live in water
Wolves drink water

4. Needs of a Population In order to survive, each population needs: Food
Water
Shelter
Space

5. Competing in an Ecosystem
Sometimes there is not enough food, water, shelter, or space to meet the needs of the populations in an ecosystem.
The challenge of meeting these needs leads to competition, a kind of contest among populations.

6. Examples of Competition
Volunteers Please!!
Snapping turtles and alligators both eat fish. What do you think would happen if the supply of fish started to decrease?

7. Adaptations
An adaptation is a characteristic that helps an organism compete in an ecosystem.
How do you adapt when the weather changes?
Turtles survive the winter by burrowing in the mud to stay warm.
Some animals change colors to blend in with their environments.

8. Symbiosis Populations don’t always compete with each other.
Sometimes they help each other to meet their basic needs.
A relationship between different kinds of organisms is called symbiosis.

9. Kinds of Symbiosis
Mutualism
Commensalism
Parasitism

10. Mutualism
Mutualism – both organisms benefit from the relationship. (ants/aphids)

11. Commensalism
Commensalism – one organism benefits and the other isn’t really affected. (sharks/remora)

12. Parasitism
Parasitism – one organism benefits and the other is harmed or killed. (roundworms in cats and dogs and mistletoe in trees)

13. Predator and Prey Relationships
In order to survive, animals must eat and avoid being eaten.
An animal that eats other animals is called a predator.
Animals that get eaten are called prey.
Predators and prey need each other in order to maintain a balance in the food supply.

14. Review QUESTIONS What is an adaptation?
Why do organisms compete? Name the four things they compete for.
A _____ is a community of living and non-living things that interact and work together.
Give an example of a population in the Mill Creek ecosystem.
Give two examples of the physical environment at Mill Creek.
Give an example of two populations interacting.

15. Symbiosis Review Questions
What is commensalism?
What is mutualism?
What is parasitism?