1. Resource Availability Gives Structure to a Community

2. A habitat differs from a niche:
The location (address) in which an organism lives.
Niche:
The role an organism plays within its community.
Includes all the factors (biotic and abiotic) an organism needs to survive, stay healthy, and reproduce.

3. Resource availability…
Natural Selection: those individuals better suited to their environment are more likely to survive and reproduce.
Adaptation: an inherited trait which makes one more likely to survive in its environment.

4. Types of Paramecium:

5. Laboratory experiment performed by ecologist G. F. Gause in 1934

6. Law of Competitive Exclusion
Two species competing for the same resources cannot coexist if other ecological factors are constant.
Competitive exclusion leads to the extinction of the competitor or an evolutionary shift towards a different ecological niche.

7. Niche Partitioning
Process by which natural selection drives competing species into different patterns of resource use.
Fundamental Niche: potential area and resources an organism is capable of using in the absence of limiting factors
Realized Niche: the portion of the fundamental niche occupied due to limiting factors such as competition

8. Niche Partitioning a. b. a. b.
When two different species compete within the same niche… a. b. a. b.
Species b is living within its fundamental niche while species a is living within its
realized niche.

9. MacArthur’s Warblers
Direct observations and field experimentation performed by Robert MacArthur, 1958

10. Evolutionary Response
Divergent evolution: evolution of one or more closely related species into different species; resulting from different adaptations to different selective pressures.

11. Ecological Equivalents
Species found in different geological regions of the world which occupy similar niches.
Ecological equivalents are never in competition.
Convergent evolution would occur between species due to similar selective forces found within their respective niches.

12. flying squirrel (North America) sugar glider (Australia)