1. Interactions in Ecosystems

2. Habitat vs Niche Habitat Niche
The habitat is the place where an organism lives out its life.
It is where the organism finds food, shelter and mates.
A niche is its role in the community and how it interacts with the environment.
How it obtains food, mates and protection from predators.

3. Red Squirrel Habitat Niche
Lives in the trees of the coniferous forest, this is its address, so to speak.
Spends much of its time searching for nuts and seeds
Builds its nest in trees,
Is food source for the great horned owl.
It also fills an important role in the forest by spreading and burying seeds which later germinate into trees.

4. Two Types of Niches
1. Fundamental niche- the set of resources a population is theoretically capable of using under ideal conditions
2. Realized niche- the resources a population actually uses
Thus, 2 species cannot coexist in a community if their niches are identical

5. Competitive Exclusion
Competitive Exclusion- two species competing for the same resources cannot coexist
The one that uses the resources more efficiently will eliminate the other

6. Competitive Exclusion
For example, the three species of North American warblers shown all live in the same trees and feed on insects.
But one species feeds on high branches; another feeds on low branches, and another feeds in the middle.

7. Competition Competition- two species use the same resources
Ex. lion and hyena

8. Predation
Predation- one organism killing the other for food

9. Coevolution
Coevolution- back and forth evolution adjustments between interacting members of a community.

10. Symbiotic Relationships
Symbiosis- relationship between two or more species
- 3 types of symbiotic relationships
1) mutualism
2) commensalism
3) parasitism

11. Mutualism
Mutualism- both species benefit
Ex. Butterfly and flower

12. Commensalism Commensalism- one benefits, one is unaffected
Ex. Clown fish and sea anemone

13. Parasitism Parasitism- one benefits, one is harmed
The parasite usually doesn’t kill the host
Ex. Wasp eggs on caterpillar

14. Tapeworm on Oprah
Video

15. Practice Problems Example #1
Bacteria and the human colon: Bacteria live in the colon of humans and are able to feed off the indigestible food that the human body cannot break down (cellulose of plants). In the process of breaking down the food, the bacteria also make much-needed vitamins that the human body in turn can use to keep healthy.
Organism 1:  helped harmed not harmed/not helped
Organism 2:  helped harmed not harmed/not helped
Symbiotic Relationship: _____________________________
Example #2
Remora and the shark: Remora fish are small fish that make their niche by picking up the scraps that sharks leave behind while feeding. The shark makes no attempt to prey on the remora fish.

16. Quiz
1. Bacteria and the human colon: Bacteria live in the colon of humans and are able to feed off the indigestible food that the human body cannot break down (cellulose of plants). In the process of breaking down the food, the bacteria also make much-needed vitamins that the human body in turn can use to keep healthy.
_____________:  helped harmed not harmed/not helped
Symbiotic Relationship: __________________
2. Remora and the shark: Remora fish are small fish that make their niche by picking up the scraps that sharks leave behind while feeding. The shark makes no attempt to prey on the remora fish.
______________:  helped harmed not harmed/not helped
Symbiotic Relationship: ____________________

17. Succession
Ecological succession- transition in species composition over ecological time

18. Primary Succesion
Primary Succession - begins in an area begun in a lifeless area; no soil, perhaps volcanic activity or retreating glacier

19. 1st Step in Primary Succession
Pioneer Species- first to colonize barren rock
Example- Lichen and Mosses

20. Pioneer Species
Lichens
Mosses

21. Succession Continuing
2nd Step- soil
3rd Step- grasses and small shrubs
4th Step- pine trees
5th Step- mature oak-hickory forest (Climax community)
- Climax Community- usually a stable forest

22. Secondary Succession
Secondary Succession- an existing community has been cleared by some disturbance that leaves the soil intact