Chapter 15, Problem 28A

Summary Introduction

To discuss:

The reason for Hardy- Weinberg principle being often violated in real populations.

Introduction:

Hardy and Weinberg showed mathematically that evolution will not occur in a population unless allelic frequencies are acted upon by forces that cause change. When these forces are absent, the allelic frequencies remain the same and evolution does not occur. This idea came to be known as the Hardy- Weinberg principle.

Answer to Problem 28A

For a population to be in genetic equilibrium, Hardy- Weinberg principle states that the allelic frequencies must remain constant. This can be possible only if there is no genetic drift, no gene flow, no mutation, and no natural selection and there should be random mating. Any violation in any one condition will render the Hardy- Weinberg equation invalid. In real populations it is rarely possible to meet all five conditions.

Explanation of Solution

According to the Hardy- Weinberg principle, when the allelic frequencies remain constant the population is in genetic equilibrium. For a population to be in genetic equilibrium, it must satisfy the following five conditions:

1. There must be no genetic drift
2. There must be no gene flow
3. There must be no mutation
4. There must be no natural selection
5. The mating should be random

In nature, populations might meet some of these five requirements, but hardly any population meets all five conditions for a long period of time. Even if one condition is violated, the population will not be in genetic equilibrium.