Short Answer
Genetic equilibrium in a population is disturbed when allele frequencies change over generations. This happens when evolutionary forces act on the population.
The main factors that disturb genetic equilibrium are mutation, migration, natural selection, genetic drift, and non-random mating. These factors change the genetic makeup of a population and lead to evolution.
Detailed Explanation :
Factors Disturbing Genetic Equilibrium
Meaning of Genetic Equilibrium
Genetic equilibrium refers to a condition where allele frequencies in a population remain constant from one generation to the next. This situation is explained by the Hardy–Weinberg equilibrium.
When a population is in genetic equilibrium, no evolution is occurring. However, in nature, populations rarely remain in equilibrium because several factors continuously act on them. These factors disturb the equilibrium and cause genetic change.
Mutation
Mutation is one of the most important factors that disturb genetic equilibrium.
Mutation is a sudden change in the DNA sequence of a gene. It creates new alleles that were not present before. Even though mutations occur at a low rate, they are the original source of all genetic variation.
When new alleles are introduced into a population through mutation, allele frequencies change. Over time, this disturbs genetic equilibrium and contributes to evolution.
Migration or Gene Flow
Migration, also called gene flow, occurs when individuals move from one population to another.
Migrating individuals bring new alleles into a population or take alleles away from it. This changes the allele frequencies of both the source and destination populations.
For example, if individuals from one population enter another population and interbreed, their genes mix with the local gene pool. This directly disturbs genetic equilibrium.
Natural Selection
Natural selection is a major factor that disturbs genetic equilibrium.
In natural selection, individuals with favorable traits survive and reproduce more successfully than others. As a result, beneficial alleles increase in frequency, while harmful alleles decrease.
This unequal survival and reproduction changes allele frequencies over generations. Therefore, natural selection continuously disturbs equilibrium and drives adaptation and evolution.
Genetic Drift
Genetic drift is a random change in allele frequencies due to chance events.
It is more significant in small populations. In such populations, some alleles may be lost completely or become very common simply by chance, not because they are beneficial.
Examples of genetic drift include population bottleneck and founder effect. Genetic drift reduces genetic variation and disturbs equilibrium.
Non-Random Mating
Non-random mating occurs when individuals choose mates based on certain traits.
This includes inbreeding or preference for specific characteristics. Non-random mating changes the distribution of genotypes in a population.
Although it may not directly change allele frequencies immediately, it affects genotype frequencies and can indirectly disturb genetic equilibrium over time.
Combined Effect of Factors
In natural populations, these factors often act together, not separately.
For example, mutation may introduce a new allele, natural selection may favor it, and migration may spread it to other populations. The combined action of these forces strongly disturbs genetic equilibrium.
Role in Evolution
Disturbance of genetic equilibrium is the basis of evolution.
Evolution is defined as a change in allele frequencies over time. Whenever genetic equilibrium is disturbed, evolution is occurring.
Thus, factors disturbing equilibrium are also called evolutionary forces.
Importance in Population Genetics
Studying these factors helps scientists understand how populations change genetically.
Population genetics uses changes in allele frequencies to measure the impact of mutation, selection, drift, and migration.
This helps explain diversity and adaptation in nature.
Importance in Conservation Biology
In conservation biology, disturbance of genetic equilibrium can be harmful or beneficial.
Small populations are especially vulnerable to genetic drift, which can reduce genetic diversity and increase extinction risk.
Understanding these factors helps design conservation strategies to protect endangered species.
Importance in Human Populations
In humans, migration and non-random mating play important roles in changing genetic structure.
Natural selection has also shaped human traits such as skin color, disease resistance, and metabolism.
Population genetics helps study these changes.
Educational Importance
Understanding factors that disturb genetic equilibrium helps students clearly connect genetics with evolution.
It explains why populations do not remain genetically stable over time.
Conclusion
Genetic equilibrium is disturbed when allele frequencies change in a population. The main factors responsible are mutation, migration, natural selection, genetic drift, and non-random mating. These factors introduce new alleles, change survival and reproduction, or cause random genetic changes. Disturbance of genetic equilibrium leads to evolution and genetic diversity. Studying these factors is essential for understanding population genetics, evolution, conservation, and biodiversity.