Question

The mode of speciation in snakes in the Western Ghats is predominantly allopatric. A researcher wants to quantify diversification of snakes in this range. From the options given, choose the most cost and time efficient way to sample snakes.

• A. Across an elevational gradient
• B. Across barriers such as valleys and rivers
• C. Intensively in one or two random locations
• D. Intensively across the entire mountain range

Hint:

The handicap principle emphasizes that the \emph{costliness} of a signal ensures its honesty. Females use these signals as cues to male quality, so costly ornaments or displays often evolve under sexual selection.

Answer 1

The Correct Option is B

Step 1: Key feature of allopatric speciation.
Allopatric divergence is driven by \emph{geographic barriers} that limit gene flow (\eg valleys, rivers, ridges).

Step 2: Sampling that targets the cause.
To detect/quantify diversification efficiently, sampling should contrast populations \emph{separated by barriers} to capture maximal divergence signals with minimal effort.

Step 3: Eliminate other options.
(A) Elevational gradients may reflect ecological (parapatric) differences, not necessarily isolation by barrier.
(C) Few random sites may miss the key contrasts.
(D) Intensively everywhere is costly and time-inefficient. Final Answer:\quad \(\boxed{\text{(B) Across barriers such as valleys and rivers}}\)