Question

Finches of Galapagos islands differ from mainland finches in size, colour and food habits. It is due to

• A. geographical isolation
• B. reproductive isolation
• C. ethological isolation
• D. seasonal isolation

Hint:

Galapagos finches are the best example of {geographical isolation leading to adaptive radiation}.

Answer 1

The Correct Option is A

Step 1: Understanding the concept.
Galapagos finches are a classic example of adaptive radiation. These finches originated from a common ancestral population but evolved differently on separate islands.
Step 2: Role of geographical isolation.
Geographical isolation occurs when populations are separated by physical barriers such as oceans or islands. This prevents interbreeding between populations.
Step 3: Evolutionary outcome.
Due to isolation and different environmental conditions, the finches adapted to different food sources, leading to variation in size, colour, and beak structure.
Step 4: Analysis of options.
(A) geographical isolation: Correct. Physical separation led to divergence and speciation.
(B) reproductive isolation: Incorrect. This develops later as a consequence, not the primary cause here.
(C) ethological isolation: Incorrect. Behavioural isolation is not the main reason in this case.
(D) seasonal isolation: Incorrect. Breeding seasons are not highlighted in this example.