Question

Consider the Pisaster Sea Star Study by Paine (1966) to answer the following questions. Please label parts of your answer with each number and write in complete sentences.

1. Define the Competitive Exclusion Principle.

2. What were the TWO main results of this study on community structure by Paine (1966)? In your answer, be sure to reference competition.

3. Is this sea star study an example of top down control or bottom up control of community structure? (5 points)

• Explain your reasoning. Be sure to reference either productivity or predation, or both, as well as competition in your answer.

4. The sea star in this study is considered a keystone species. What does this mean in terms of the organism's effect on community structure?

Answer 1

1. Competitive Explusion Principle states that two closely related species competing for same resources cannot co-exist in a niche and eventually one of the two(less superior) will be eliminated.It was put forth by Gause.
2. The main results were:-a.) Predation maintains the community diversity by keeping competition under control. b.) Once the prdator was removed the competition amaong it's prey increased significantly hence leading to ecological instability.
3. Top Down Control is limitation placed by factors that control death by diseases or natural disaster or predation whereas Bottom Up control is limitation placed by resources for growth such as food,habitat,space ctc.
4. A key stone species is the one which has more effect on environment,without which there would be a drastic difference in environment or in worst case can even cease to exist altogether.