Chapter 15.3, Problem 5MI

Summary Introduction

To identify:

Three ways by which genetic equilibrium can be disrupted.

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 5MI

For a population to be in genetic equilibrium,Hardy- Weinberg principle states that the allelic frequencies must remain constant. Genetic equilibrium can be disrupted through:

1. Genetic drift
2. Gene flow
3. Mutation

Explanation of Solution

According to the Hardy- Weinberg principle, when the allelic frequencies remain constant the population is in genetic equilibrium. Genetic equilibrium can be disrupted through:

1. Genetic drift- Any change in allelic frequencies in a population that is due to chance is called genetic drift. In large populations, alleles drift to ensure that the allelic frequency of entire population remains constant from one generation to next. In small populations genetic drift is prominent and there is a greater chance of losing an allele.
2. Gene flow- When no genes enter a population and no genes leave a population, it is in genetic equilibrium but in reality few populations are isolated. Migration and movement of individuals disrupts the genetic equilibrium.
3. Mutation- It involves random changes in genetic material that may change the allelic frequencies and thus disrupt the genetic equilibrium of a population.

In nature, populations might meet some of these requirements. Even if one condition is violated, the population will not be in genetic equilibrium.