Read following statements and identify the incorrect one in regards to Hardy- Weinberg equilibrium.

Options

A. The allelic frequency in a population are stable and constant from generation to generation
B. Gene migration or gene flow is essential for the maintenance of Hardy - Weinberg principle in disturbed
C. Evolution occurs when Hardy - Weinberg principle in disturbed
D. When frequency measured, differs from expected values, the difference indicates the extent of evolutionary charge

Answer

To identify the incorrect statement regarding Hardy-Weinberg equilibrium, we will analyze the provided statements step by step.

### Step-by-Step Solution:

1. **Understanding Hardy-Weinberg Equilibrium**:
- Hardy-Weinberg equilibrium describes a theoretical state in which allele frequencies in a population remain constant from generation to generation, provided that certain conditions are met. This means that the gene pool remains stable.

**Hint**: Remember that Hardy-Weinberg equilibrium is about stability in allele frequencies over generations.

2. **Identifying Factors Affecting Equilibrium**:
- There are five main factors that can disturb Hardy-Weinberg equilibrium:
1. Gene migration (gene flow)
2. Genetic drift
3. Mutation
4. Genetic recombination
5. Natural selection

**Hint**: Consider how each of these factors can introduce changes in allele frequencies.

3. **Analyzing the Statements**:
- **Statement 1**: "The allele frequency in our population are stable and constant from generation to generation."
- This statement is true as it reflects the essence of Hardy-Weinberg equilibrium.

- **Statement 2**: "Gene migration or gene flow is essential for the maintenance of Hardy Weinberg Equilibrium."
- This statement is incorrect. Gene migration disrupts the equilibrium by introducing new alleles and changing allele frequencies.

- **Statement 3**: "Evolution occurs when Hardy-Weinberg equilibrium is disturbed."
- This statement is true. Disturbance in the equilibrium indicates changes in allele frequencies, which is a sign of evolution.

- **Statement 4**: "When we measure the frequency, it differs, so if it differs, then the expected value. So this difference tells evolutionary change."
- This statement is also true, as differences from expected values indicate evolutionary changes.

4. **Conclusion**:
- The incorrect statement regarding Hardy-Weinberg equilibrium is **Statement 2**: "Gene migration or gene flow is essential for the maintenance of Hardy Weinberg Equilibrium."

### Final Answer:
The incorrect statement is: **Gene migration or gene flow is essential for the maintenance of Hardy Weinberg Equilibrium.**