Question

Two sister species of bulbuls have non-overlapping distributions. One is distributed in India and the other in Sri Lanka. Which of the following modes of speciation is the most parsimonious explanation for this pattern?

• A. Allopatric speciation
• B. Sympatric speciation
• C. Parapatric speciation
• D. Peripatric speciation

Hint:

Allopatric speciation is the most common form of speciation when populations are geographically separated.

Answer 1

The Correct Option is A

When populations of the same species become geographically isolated and eventually evolve into separate species, it is called allopatric speciation.

Step 1: Understand the concept of allopatric speciation.
Allopatric speciation occurs when a population is divided by a physical barrier (like a mountain, river, or ocean), leading to genetic divergence. In the case of the bulbuls, the populations are geographically isolated in India and Sri Lanka, creating the conditions for allopatric speciation.

Step 2: Consider other types of speciation.
- Sympatric speciation: Occurs when a species evolves into two without geographical isolation, typically due to ecological, behavioral, or temporal factors. This is not applicable to the given scenario.
- Parapatric speciation: Occurs when populations are partially separated but still have some contact, not applicable here.
- Peripatric speciation: A form of allopatric speciation where small populations at the edge of a species range evolve into new species. This is less likely to apply given the large geographical separation of the populations.

Step 3: Conclusion.
Thus, the most parsimonious explanation for this pattern is allopatric speciation.