Which statement best describes allopatric speciation?

• A. Allopatric speciation requires geographic isolation
• B. It occurs without geographic barriers
• C. It occurs only in plants
• D. It cannot lead to speciation

Answer: (A)

Allopatric speciation hinges on geographic isolation. When a physical barrier splits a population, gene flow between the two groups is greatly reduced, allowing genetic differences to accumulate through mutation, drift, and adaptation to different environments. Over time, these differences can be strong enough that the two groups can no longer interbreed, even if the barrier were removed. This is why geographic isolation is essential to allopatric speciation. The other statements don’t fit because the process requires a barrier, it is not limited to plants, and it can indeed produce new species.