1. 4.2 Niches and Community Interactions

2. Habitats and Niches
Habitat: the area where an organism lives. Includes both the biotic & abiotic factors
Niche: the full range of physical & biological conditions in which an organism lives & the way in which the organism uses those conditions

3. What might determine where an organism lives?
Tolerance to survive in that area
Amount of Resources

4. Tolerance
Every species has its own range of tolerance, the ability to survive and reproduce under a range of environmental circumstances.
The organism must expend more energy to maintain homeostasis, and so has less energy left for growth and reproduction.

5. Resources and the Niche
The term resource can refer to any necessity of life, such as water, nutrients, light, food, or space.
For plants, resources can include sunlight, water, and soil nutrients.
For animals, resources can include nesting space, shelter, types of food, and places to feed.

6. Niche includes… Place in the food web
Range of temp. organism needs to survive
Type of food organism eats
How it obtains food
Who uses the organism for food
Physical conditions required to survive
When & how organism reproduces

7. Competitive Exclusion Principle
No two species can share a niche in the same habitat!!
example is the Warblers & bacteria…

8. Warbler Niches Each of these warbler species has a different niche in its spruce tree habitat. By feeding in different areas of the tree, the birds avoid competing with one another for food.  

9. The Competitive Exclusion Principle
Two species of paramecia (P. aurelia and P. caudatum) were first grown in separate cultures (dashed lines) . In separate cultures, but under the same conditions, both populations grew.
When both species were grown together in the same culture (solid line), one species outcompeted the other, and the less competitive species did not survive.

10. Community Interactions
Community interactions, such as competition, predation, and various forms of symbiosis can powerfully affect an ecosystem.
Cobra Vs. Mongoose

11. Competition
Competition: occurs when organisms of the same or different species attempt to use a resource at the same place and time.
Direct competition between different species almost always produces a winner and a loser—and the losing species dies out.
Trees in competition for light

12. Predation Predation: one organism captures and feeds on another
Predators can affect the size of prey populations in a community and determine the places prey can live and feed.

13. Keystone Species
Changes in the population of a single species, often called a keystone species, can cause dramatic changes in the structure of a community.
In the cold waters off the Pacific coast of North America, for example, sea otters devour large quantities of sea urchins (which eat kelp).

14. Keystone Species

15. Symbiosis Clownfish and sea anemone
Symbiosis: Any relationship in which two species live closely together
Mutualism: both species benefit
Rhino and Egret
Clownfish and sea anemone
Hummingbird and Flower

16. Symbiosis
Commensalism: one species benefits, other neither harmed nor helped
Barnacles on a whale

17. Symbiosis Parasitism: one organism lives in or in another & harms it
A flea or tick feeds on the blood of its host and may also carry disease-causing microorganisms

18. What determines where an organism might live?
Tolerance
Resources

19. What happens to organisms that try to compete for the same resource?
One will win and obtain the resource
The other may die off if it can’t find its resource

20. What are the three main types of symbiosis?
Commensalism
Mutualism
Parasitism