Question

Two species of Paramecia, Paramecium aurelia and Paramecium caudatum were grown in a single flask where bacteria were used as the food source. The graph shows their growth rate. Choose the correct statement regarding the same from the following.


I. It is an example of Gause’s competitive exclusion principle.
II. Paramecium caudatum is the competitively superior species.
III. Paramecium aurelia and Paramecium caudatum occupy the same niche.

• A. I and II
• B. I only
• C. II only
• D. I and III

Answer 1

The correct option is D I and III

Competition is a type of population interaction in which the fitness of one species is significantly lower in the presence of another species. It occurs when more than one species compete for the same resources that are limiting and has a negative effect on both the interacting species (-/- interaction).

Since both Paramecium aurelia and Paramecium caudatum were grown together in a single flask where bacteria were used as the food source, they share the same niche. So, statement III is correct.

It can be noticed from the graph given above that Paramecium aurelia grew successfully in the mixture while the growth of Paramecium caudatum declined. So Paramecium caudatum (competitively inferior) was unable to compete with Paramecium aurelia (competitively superior) for the same limited food resource and thus got eliminated. Therefore statement II is incorrect.
This is an example of Gause’s competitive exclusion principle which states that two closely related species competing for the same resources cannot coexist indefinitely and the competitively inferior one will be eliminated eventually when the resources are limiting. Hence, statement I is correct.