Which phenomenon is essential for the formation of new species along with natural selection ?

Options

A. Mutation
B. Reproductive isolation
C. Genetic drift
D. Gene flow

Answer

**Step-by-Step Text Solution:**

1. **Understanding Speciation**: Speciation is the process through which new species arise. It often occurs when populations of a species become isolated from each other and undergo different evolutionary changes.

2. **Role of Natural Selection**: Natural selection is a key mechanism of evolution, where individuals with favorable traits are more likely to survive and reproduce. However, natural selection alone does not account for the formation of new species.

3. **Identifying Essential Phenomena**: To form new species, other phenomena must also contribute alongside natural selection. The options provided are mutation, reproductive isolation, genetic drift, and gene flow.

4. **Exploring Genetic Drift**: Genetic drift refers to random changes in allele frequencies within a population, particularly in small populations. Over time, genetic drift can lead to significant genetic divergence between populations.

5. **Linking Genetic Drift to Speciation**: As genetic drift causes a subpopulation to become genetically distinct from its original population, it can lead to the development of new traits that may not be present in the original population. This divergence can ultimately result in speciation, especially when combined with natural selection.

6. **Conclusion**: Therefore, alongside natural selection, genetic drift is an essential phenomenon for the formation of new species.

**Final Answer**: Genetic Drift

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