Which of the following factors is necessary for allopatric speciation to occur?

• A. Hybridization between closely related species
• B. Continuous gene flow between populations
• C. Polyploidy within a single population
• D. Geographic isolation of populations

Answer: (D)

Verified step by step guidance

1. Understand the concept of allopatric speciation: Allopatric speciation occurs when populations of the same species become geographically isolated, preventing gene flow between them. Over time, genetic differences accumulate, leading to the formation of new species.
2. Analyze the options provided: Hybridization between closely related species, continuous gene flow between populations, polyploidy within a single population, and geographic isolation of populations.
3. Eliminate incorrect options: Hybridization typically leads to the formation of hybrids, not speciation through geographic isolation. Continuous gene flow prevents genetic divergence, making speciation unlikely. Polyploidy is a mechanism of sympatric speciation, not allopatric speciation.
4. Focus on the correct option: Geographic isolation of populations is the key factor for allopatric speciation because it physically separates populations, halting gene flow and allowing evolutionary processes like mutation, genetic drift, and natural selection to act independently on each population.
5. Conclude the reasoning: Geographic isolation creates the conditions necessary for populations to diverge genetically over time, eventually leading to the formation of distinct species through allopatric speciation.