According to Hugo de Vries, the mechanism of evolution is:

Options

A. Multiple step mutations
B. Saltation
C. Phenotypic variations
D. Minor mutations

Answer

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

1. **Understanding Hugo de Vries' Contribution**: Hugo de Vries was a Dutch botanist and one of the early proponents of the mutation theory of evolution. He proposed that evolution occurs through sudden and large changes, rather than gradual changes.

2. **Key Concepts**:
- **Multistep Mutation**: This refers to the idea that evolution occurs through a series of mutations. However, de Vries did not support this view as the primary mechanism of evolution.
- **Saltation**: This term refers to sudden jumps in evolution, which de Vries argued were significant for evolutionary change. He believed that new species could arise from large mutations rather than gradual changes.
- **Phenotypic Variation**: This is the observable physical or biochemical characteristics of an organism. While important for natural selection, de Vries did not consider it the primary mechanism of evolution.
- **Minor Mutations**: These are small genetic changes that can occur within a population. De Vries believed that these minor mutations were not sufficient to drive evolution.

3. **Conclusion**: According to Hugo de Vries, the mechanism of evolution is primarily through **saltation**, which involves sudden and significant changes rather than gradual mutations or minor variations.

**Final Answer**: The mechanism of evolution according to Hugo de Vries is **Saltation**.

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