Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Abingdon tortoise in Galapagos islands became extinct within a decade after goats were introduced.
Reason R: Goats were more efficient at browsing than Abingdon tortoise.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. A is not correct but R is correct
• B. Both A and R are correct and R is the correct explanation of A
• C. Both A and R are correct but R is not the correct explanation of A
• D. A is correct but R is not correct

Hint:

This case study is a classic textbook illustration of Gause's Competitive Exclusion Principle in real-world habitats. Introduced or invasive species often have superior resource exploitation traits, leading to the rapid decline of native species.

Answer 1

The Correct Option is B

Concept:

• Interspecific Competition: Occurs when different species compete for the same limiting resources (like food).

• Competitive Exclusion Principle (Gause): States that two species competing for the same limiting resources cannot coexist indefinitely, and the competitively inferior species will eventually be eliminated.

Step 1: Evaluate Assertion A
Assertion A states that the Abingdon tortoise in the Galapagos Islands went extinct within a decade after goats were introduced.
This is a well-documented ecological fact resulting from intense interspecific resource competition.

Step 2: Evaluate Reason R
Reason R states that goats had greater browsing efficiency than the Abingdon tortoise.
This is true, as goats are agile and consume vegetation much faster and closer to the ground than the slow-moving tortoises.

Step 3: Determine if R is the correct explanation of A
The extinction of the tortoises (Assertion) occurred because the newly introduced goats consumed the limited vegetation far more efficiently (Reason), leaving no food for the tortoises.
Thus, R is the correct explanation of A.