What is Genetic Variation?

Genetic Variation is the difference in DNA sequence within a population or among individuals of the same species. It can occur in both germ cells (sperm and egg) and somatic cells. The primary source of genetic variation is Mutation, Genetic recombination, and gene flow in the population, recombination. Genetic variation in a human population includes skin color, hair color, dimples, freckles, and blood type. Genetic variation increases a species’ chances of survival. In this article, we will study Genetic Variation, Types of genetic variation, its Causes, Advantages, and disadvantages of variation, and its importance.

Genetic Variation Definition

Genetic Variation is the diversity in genetic information among individuals or between populations among the same species arising from mutations, Genetic recombination, and gene flow.

Genetic Variation

Genetic variation is the variation in the genetic material (DNA sequence) within a genome. Genes are units of hereditary information, and they carry instructions for building proteins. Genes exist in different forms, called alleles, which further add to genetic variation. It introduces different traits in an organism.

The genetic variation is passed to the next generation if a trait is advantageous and helps the individual survive and reproduce. This process is called natural selection. genetic variation is the raw material for evolution. Without genetic variation, a population can’t evolve to respond to changing environmental variables and may face a higher risk of extinction.

Types of Genetic Variation

Genetic variation is the difference in genotype between two individuals within the same species. It can occur through various mechanisms, that results in genetic changes within a population. The different types of genetic variation are:

Single Base-Pair Substitution

It is also called Single Nucleotide Polymorphism (SNP) or a point mutation, that involves replacing a single nucleotide base with another in a DNA molecule. It can result in an incorrect amino acid in the encoded protein, that can cause altered protein function. At least 10% of human inherited disease are caused due to point mutation, making it the most common type of mutation. Point mutation is further divided into:

1. Transition: A point mutation in which a purine is substituted by another purine (e.g. A→G) or a pyrimidine is substituted by another pyrimidine (e.g. T→C).
2. Transversion: A modest mutation in which a purine is substituted by another pyrimidine (e.g. A→C) or a pyrimidine is substituted by another purine (e.g. T→G).

Insertion or Deletion

Insertions and deletions are together known as indels. Indels involves the addition (insertion) or removal (deletion) of one or more nucleotides in a DNA sequence which changes the “reading frame” of the sequence. This is because the genetic code is read in codons, which are three bases long. It can affect the synthesis of protein or functional RNA molecules. Deletions are highly unlikely to be reversed.

Structural Variation

Structural Variation (SV) is a large difference in the structure of two genomes that is regions of DNA that are about 1 kb or larger. It can have significant effects on gene expression, phenotype, and can contribute to genetic diversity within a population. They can include:

• Inversions
• Balanced translocations
• Genomic imbalances
• Copy number variants (CNVs)

Aslo Read: Genetic Code and Mutation

Causes of Genetic Variation

Genetic variation can be caused by a number of factors, including

• Mutation: Mutation refers to the change in the DNA sequence during replication or due to external factors like radiation. It creates slightly different versions of genes, called alleles. It introduces new genetic variant that make every individual unique.
• Gene Flow or Gene Migration: When organisms migrate to a new habitat and introduces new genetic material into a population. This can alter genetic diversity by changing allelic frequencies in populations.
• Recombination: During the process of cell division( Meiosis) genetic material from both parents is shuffled. It leads to unique combinations of alleles in offspring.
• Sexual Reproduction: During fertilization alleles are segregated and united randomly united resulting in genetic variation. Crossing over during prophase I of cell division creates different chromosomes in offspring compared to their parents resulting in genetic variation.
• Genetic Drift: Genetic drift leads to loss or fixation of alleles, which influences genetic diversity.
• Chromosomal aberrations: It affect the structure or number of chromosomes. It may include deletion, insertion, exchange, and translocation. The most common chromosomal disorder is trisomy 21, which is the primary cause of Down syndrome. It introduces genetic variation.
• Other Factors: Random mating, Random fertilization, and Environmental factors like radiation. Genetic variation acts alongwith environmental and behavioral factors to produce phenotypic diversity.

Examples of Genetic Variation

Genetic variation is present in different form that influences the diversity of traits within a population. Some of the examples of Genetic variation in different species are as follows:

• Genetic variation can help biological species to be adaptable to changes in its environment. For example, the Florida panther was saved from extinction by the introduction of genotypic variation via breeding with Texas panthers.
• Some examples of genetic variation in humans: Skin color, Hair color, Dimples, Freckles, Blood type.
• Some examples of genetic variation in plants: Modified leaves of carnivorous plants, Development of flowers that resemble insects to lure plant pollinators.
• Some examples of genetic variation in animals: Cheetahs with stripes, Animals that pretend to be dead, Albinism, Snakes that fly, Animals that imitate leaves, Galapagos finches, and Fruit flies.

Advantages of Genetic Variation

The advantage of genetic variation includes:

• Adaptability: Genetic variation allows populations to adapt to changing environments, such as climate change or new diseases.
• Disease resistance: Genetic variation can result in some individuals having increased resistance to certain diseases.
• Diversity: Genetic variation creates diversity.
• Essential for growth: Variation is essential for growth and takes place during sexual reproduction.
• New traits: Discontinuous variations produce new traits in the organisms.

Disadvantages of Genetic Variation

The disadvantages of genetic variation includes:

• Genetic variation can cause some undesired effects like genetic disorder, diseases, etc.
• Variation causes lose of linkages of chromosomes, which leads to mutations. Most mutations are deleterious.
• Variation can lead to decreased fitness if it results in traits that are less adaptive to the environment.
• Too much diversity can possibly lead to challenges in maintaining a cohesive population.

Why is Genetic Variation Important?

Genetic variation plays a fundamental role in the evolution, adaptation, and functioning of living organisms. Some of the reasons why genetic variation is important is explained as follows:

• Genetic variation allows natural selection to increase or decrease the frequency of alleles in a population. This leads to changes in the gene pool of organisms and guides evolution.
• It helps organisms adapt to changing environment and increase their chance of survival.
• Genetic variation helps a species,either plant or animals resistant to certain diseases.
• It increases the reproductive success of a population and also an important aspect of biodiversity.
• Variation gives each organism a distinct individuality.
• Variation helps maintain environmental stability.

Conservation of Genetic Variation

Genetic variation is important for human well-being and protecting species from extinction. Maintaining genetic variation is critical for wild populations to survive, reproduce, and adapt to future environmental changes. Some strategies for conserving genetic variation includes:

• Populations can be maintained in parks, ecological reserves, and other protected areas.
• Samples of seeds, individuals, or tissues can be collected and maintained ex situ, for example, in seed banks.
• The inbreeding coefficient should be minimized.
• To preserve genetic variation, the selection of closely related individuals should be avoided.

FAQs – Genetic Variation

What is Meant by Genetic Variation?

Genetic variation is the differences in DNA segments or genes between individuals. It is caused by mutation, sexual reproduction, gene migration and chromosomal aberrations.

What are Multiple Alleles? Give an Example.

Multiple alleles are different versions of a trait that exist within a population. For example, a gene that encodes for height can have two alleles, one for tallness and one for dwarfness. 

What is the Difference Between a Gene and an Allele?

Gene is the basic unit of the hereditary that is composed of two alleles. Alleles on the other hand is a variant form of gene and can be either dominant or recessive allele.

What are 5 Causes of Genetic Variation in a Population?

The causes of genetic variation in a population includes mutation, genetic recombination, gene flow, crossing over, random fertilization and environmental factors like radiation.

Define Geographic Variation.

Geographic Variation is the differentiation of populations within a species’ natural geographic range. It is determined by geographic variables such as climate or ecological niche.

What is the Importance of Variation?

Genetic variation allows a population to adapt through natural selection and survive in the long term. Individuals who are genetically best adapted to an environment are more likely to survive and reproduce

What are the 4 Types of Genetic Variation?

The 4 type of genetic variation are structural variations, single-nucleotide polymorphisms, insertion and deletion variations, copy number variations, and translocations and inversions.

What are Genetic Variation Examples?

Some example of genetic variation includes skin color, frickels, dimples, modified leaves of carnivorous plants, stripes on cheetas, albinism, and Galapagos finches.