List three mechanisms by which variant genotypes can be produced in nature.

Explanation

To answer the question about the three mechanisms by which variant genotypes can be produced in nature, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Mutation**:
- **Definition**: Mutation refers to a sudden change in the genetic material of an organism. This can occur at various levels, including point mutations (changes in a single nucleotide) or larger chromosomal alterations.
- **Example**: A classic example is sickle cell anemia, which results from a point mutation in the beta-globin gene. This mutation alters the amino acid sequence, leading to a change in the phenotype of red blood cells from disc-shaped to sickle-shaped.

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