Question

In the phylogenetic trees shown, the tips represent different species of geckos (labeled A to E) and the areas to which they belong. Which one of these is most consistent with the hypothesis that the geckos colonized the Western Ghats from Northeast India through the Eastern Ghats?

• A. P
• B. Q
• C. R
• D. S

Hint:

Match your sampling design to the hypothesized speciation mechanism: for allopatry, sample \emph{across} barriers; for ecological divergence, sample \emph{along} environmental gradients.

Answer 1

The Correct Option is B

To determine which phylogenetic tree (P, Q, R, or S) aligns with the hypothesis that geckos colonized the Western Ghats from Northeast India through the Eastern Ghats, we must analyze the specific hypothesis against each tree structure provided.

The hypothesis suggests a migration pathway: Northeast India → Eastern Ghats → Western Ghats. This implies that the most likely tree would show a branching pattern where species from the Western Ghats are closely related to species from the Eastern Ghats, and species from the Eastern Ghats are closely related to those from Northeast India.

Analyzing option Q:

• The tree in option Q displays species from the Western Ghats clustering with species from the Eastern Ghats, supporting the notion of a sequential colonization.
• Additionally, species from the Eastern Ghats show a close genetic relationship with those from Northeast India, which aligns with the proposed migration path.

Thus, option Q most consistently supports the hypothesis of migration from Northeast India to the Western Ghats through the Eastern Ghats, making it the correct answer.