Module 8 Lesson 7 - 4 (Lab)

Intraspecific and Interspecific Competition among Protozoan Paramecium

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Competition between members of the same species limits growth significantly. Slight genetic differences between gene pool members allow only some members to thrive. Competition between species affects the growth curve significantly. This lab requires you to manipulate a variable to determine its effect on intraspecific and interspecific competition.

Problem

What is the effect of competition for resources on intraspecific and interspecific competition?

Procedure

1. Click the following link to access the virtual lab on Population Biology.
   
   
2. Click the Information button to obtain background information on Paramecium.
   
   
3. You must design this experiment. After deciding how to proceed, fill the test tubes with samples of P. caudatum and P. aurelia stock culture.
   
   
4. Write a hypothesis on how you will test intraspecific and interspecific competition by observing the growth rates of P. caudatum and P. aurelia.
   
   
5. Click the microscope on the back bench.
   
   
6. Make wet mounts of your samples on clean microscope slides.
   
   
7. Count the number of cells in your microscope slides and record your data by clicking the Table button at the bottom.
   
   
8. Continue recording until day 16.
   
   
9. Click the graph button and analyze the graph.
   

Analysis

1. How did you test your hypothesis?
   
   
2. When did P. caudatum sample population reach its carrying capacity?
   
   
3. When did P. aurelia sample population reach its carrying capacity?
   
   
4. What happened when P. caudatum and P. aurelia were grown together?

Conclusions

Can the two species of Paramecium occupy the same niche? Do your findings support the principle of competitive exclusion?