Variation in gene frequencies within populations can occur by chance rather than by natural selection. This is referred to as

Options

A. Genetic drift
B. Random mating
C. Genetic load
D. Genetic flow

Answer

To answer the question regarding the variation in gene frequencies within populations occurring by chance rather than by natural selection, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Gene Frequencies**:
- Gene frequencies refer to how often a particular gene variant (allele) appears in a population. Variations in these frequencies can indicate changes in the genetic makeup of the population over time.

**Hint**: Think about what gene frequencies represent in a population.

2. **Identifying Causes of Variation**:
- Variations in gene frequencies can occur due to several factors, including natural selection, mutation, migration, and genetic drift. Natural selection is a process where certain traits become more common due to their advantages in survival and reproduction.

**Hint**: Consider the different mechanisms that can lead to changes in gene frequencies.

3. **Focusing on Chance Events**:
- The question specifies that the variation occurs by chance rather than by natural selection. This indicates we are looking for a process that is random and not influenced by the advantages of certain traits.

**Hint**: Reflect on processes that involve random changes in gene frequencies.

4. **Defining Genetic Drift**:
- Genetic drift is a mechanism of evolution that refers to random changes in the frequencies of alleles in a population. These changes can occur due to chance events, especially in small populations where random events can have a larger impact.

**Hint**: Think about how random events can affect small populations differently than larger ones.

5. **Conclusion**:
- Based on the understanding that the variation in gene frequencies can occur by chance, the correct term for this process is "genetic drift."

**Final Answer**: The process referred to is **genetic drift**.

### Summary of the Answer:
The variation in gene frequencies within populations that occurs by chance rather than by natural selection is referred to as **genetic drift**.