Hardy and Weinberg proposed a principal for

Options

A. Founder's effect .
B. Sewell Wright effect .
C. Genetic drift
D. Non-evolving population .

Answer

**Step-by-Step Solution:**

1. **Understanding the Hardy-Weinberg Principle**: The Hardy-Weinberg principle states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. This principle is foundational in population genetics.

2. **Key Components of the Principle**:
- **Alleles**: In any population, there are variations in traits controlled by alleles. For simplicity, let's denote two alleles as P (dominant) and Q (recessive).
- **Genotypes**: The possible genotypes in the population can be:
- Homozygous dominant (PP)
- Homozygous recessive (QQ)
- Heterozygous (PQ)

3. **Frequency Representation**:
- The frequency of homozygous dominant individuals (PP) is represented as \( p^2 \).
- The frequency of homozygous recessive individuals (QQ) is represented as \( q^2 \).
- The frequency of heterozygous individuals (PQ) is represented as \( 2pq \).

4. **Equation of Frequencies**: According to the Hardy-Weinberg principle, the sum of the frequencies of all genotypes must equal 1:
\[ p^2 + 2pq + q^2 = 1 \]
This equation reflects that the entire population is made up of these three genotypes.

5. **Conditions for Hardy-Weinberg Equilibrium**: The Hardy-Weinberg equilibrium will be maintained under the following conditions:
- No mutations
- No gene flow (migration)
- Random mating
- Large population size (to minimize genetic drift)
- No selection (natural or artificial)

6. **Implications of the Principle**: If the conditions are met and allele frequencies remain constant over generations, it indicates that the population is not evolving. Any change in allele frequencies suggests that evolutionary forces (like natural selection, genetic drift, etc.) are at play.

7. **Conclusion**: The Hardy-Weinberg principle provides a baseline to measure evolutionary changes in populations. It helps in understanding the genetic structure of populations and the forces that drive evolution.

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