Which of the following factors would not contribute to allopatric speciation?
a. The separated population is small, and genetic drift occurs.
b. The isolated population is exposed to different selection pressures than the ancestral population.
c. Different mutations begin to distinguish the gene pools of the separated populations.
d. Gene flow between the two populations is extensive.

Verified step by step guidance

1. Understand the concept of allopatric speciation: Allopatric speciation occurs when populations of the same species become geographically isolated, leading to genetic divergence and the formation of new species. Key factors include lack of gene flow, genetic drift, mutations, and differing selection pressures.
2. Analyze each option to determine its relevance to allopatric speciation: For example, genetic drift (option a) can lead to changes in allele frequencies in small populations, contributing to speciation. Similarly, differing selection pressures (option b) and mutations (option c) can drive divergence between populations.
3. Focus on the role of gene flow (option d): Gene flow involves the exchange of genetic material between populations. Extensive gene flow counteracts genetic divergence by homogenizing the gene pools of the populations, which would prevent allopatric speciation.
4. Compare the options: Identify which factor does not align with the mechanisms of allopatric speciation. Extensive gene flow (option d) directly opposes the isolation required for speciation, making it the factor that would not contribute to allopatric speciation.
5. Conclude that the correct answer is the factor that prevents genetic divergence and speciation, which is extensive gene flow (option d).

Key Concepts

Allopatric Speciation

Allopatric speciation occurs when a population is geographically separated, leading to reproductive isolation. This separation can result from physical barriers like mountains or rivers, preventing gene flow between groups. Over time, the isolated populations may evolve independently, potentially leading to the emergence of new species.

Genetic Drift

Genetic drift is a mechanism of evolution that refers to random changes in allele frequencies within a population, particularly in small populations. It can lead to significant genetic divergence between separated populations, contributing to speciation. This process can result in the loss of genetic variation and the fixation of certain traits purely by chance.

Gene Flow

Gene flow is the transfer of genetic material between populations through migration and interbreeding. Extensive gene flow between two populations can counteract the effects of speciation by homogenizing their gene pools, making it less likely for them to diverge into separate species. In the context of allopatric speciation, reduced gene flow is essential for the process to occur.