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Natural Selection : Process of Evolution and Variations

Grade 10
May 3, 2023

In this article, we’ll learn about evolution and variations through natural selection. Let’s begin

Introduction to Variation

Genetic variety refers to the differences in the genomes of individuals of the same species. A genome contains all of an organism’s hereditary information, including its genes. The human genome, for example, has between 20,000 and 25,000 genes. Genes are genetic information units that convey instructions for protein synthesis.

Cells function as a result of the genes that are encoded inside these proteins. Because each parent cell or organism provides a single copy of its genes to its child, most organisms that reproduce sexually have two copies of each gene.

Furthermore, genes can exist in slightly different versions, known as alleles, contributing to genetic variationFor example, the genotype for a specific attribute, such as hair texture, is determined by the mix of alleles of a gene that an individual inherits from both parents.

Different colors of Birds
Different Colors of Birds

An individual’s genotype for a trait influences the phenotype and the observable characteristics, such as whether that individual has straight, wavy, or curly hair. Genetic diversity within a species can arise from a variety of sources. Mutations, which are alterations in the sequences of genes in DNA, are one source of genetic variation.


Another source is gene flow or the transmission of genes between different groups of organisms. Finally, genetic variation can occur due to sexual reproduction, which results in the formation of novel gene combinations. Genetic variety in a collection of organisms allows some species to thrive in their environment better than others.

Phenotypes of flies
Phenotypes of flies

Even within a small population, organisms can differ dramatically in terms of how well-suited they are to live in a given environment. For example, consider moths of the same species with different colored wings. Moths with wings similar to the tree bark color are better at camouflaging than moths of a different hue.

As a result, the tree-colored moths have a better chance of surviving, reproducing, and passing on their genes. This process is known as natural selection and is the driving factor behind evolution.


Types Of Variation

Variation refers to all the differences within a population of the same species. These distinctions are the result of the following:

  • Genetic variation refers to changes between individuals that are inherited from parents, such as the color of your eyes, hair, and skin.
  • Environmental variation – these are changes between individuals that are not inherited but are caused by the environment in which the organism lives, such as scars and tattoos.
  • Genetic and environmental variation – variations between people produced by genetic and environmental variables, such as height and weight.

Variation in Population

The gene pool is the sum of all the genes and gene combinations found in a population of organisms of the same species. It may be defined by mentioning the frequencies of the various genetic constitutions. The requirement of genetic variety for evolutionary change may be interpreted in terms of the gene pool.

Evolution and Variations (Varieties of Mouse)
Evolution and Variations (Varieties of Mouse)

Process of Evolution and Variations

The higher the genetic variation in a population, the greater the possibility of evolution. As the number of variable gene loci rises, as does the number of alleles at each locus, the risk that specific alleles may change in frequency at the cost of their alternative climbs. R.A. Fisher, a British geneticist, statistically proved a clear relationship between the quantity of genetic variation in a population and the pace of evolutionary change via natural selection.

His fundamental theorem of natural selection (1930) encapsulates this: “The rate of growth in the fitness of every organism at any moment is equal to its genetic variation in fitness at that time. “

Because it was created from two separate single-strain populations, the mixed population had the most initial genetic variation. The number of individuals in the population was counted regularly to assess adaptation to the experimental setting. Both forms of the population experienced evolutionary adaptation to the environment and maintained increasing numbers as generations continued.

However, the pace of evolution in the mixed group was faster than the pace of evolution in the single-strain groups. The bigger the starting quantity of genetic variation, the faster the pace of evolution.

Measuring Gene Variability

Because genetic variety determines a population’s ability to evolve, evolutionists are interested in assessing the breadth of such a variation in the natural population. For example, plant and animal species are diverse, such as bloom colors, growth behaviors in plants or shell forms, and banding patterns in snails.

Distinctions in facial features, hair and skin color, height, and weight are more easily observed in humans, although such morphological differences exist in all species groups. One issue with morphological variation is that it is unclear how much of it is due to hereditary causes and how much is due to environmental effects.

Variation Causes

DNA mutation, gene flow (the transfer of genes from one population to another), and sexual reproduction are significant sources of genetic diversity. Because environments are unstable, genetically variable populations will be able to adapt to changing conditions better than those who do not have genetic variety.

  • Mutation in DNA:

Variations in gene sequences can occasionally be beneficial to an organism. However, the majority of mutations that arise in genetic variation create features that are neither advantageous nor disadvantageous. Mutations affect genes and alleles in a population, resulting in genetic diversity. They may involve a single gene or a whole chromosome.

  • The flow of Genes:

Gene flow, also known as gene migration, introduces new genes into a population as organisms migrate to a new habitat. The availability of novel alleles in the gene pool allows for creating new gene combinations. The emigration of organisms from a community can also affect gene frequencies. Introducing new organisms into a population may aid in adapting organisms to changing environmental conditions.

  • Sexual Reproduction:

Sexual reproduction promotes genetic variety by generating new gene combinations. Meiosis is the process through which sex cells or gametes are formed. Genetic variety arises when alleles in gametes are separated and randomly combined during fertilization. Through meiosis, genetic recombination of genes occurs during crossing over or swapping gene segments in homologous chromosomes.

Variation Examples

Skin color, hair color, dimples, freckles, and blood type are all genetic variations that may exist in a human population. Plant genetic variety includes modified leaves of carnivorous plants and the development of flowers that resemble insects to attract plant pollinators. Gene flow is a frequent source of plant gene variation.

Pollen travels long distances from one location to another, thanks to the wind or pollinators. Albinism, striped cheetahs, flying snakes, animals that play dead, and creatures that imitate leaves are all examples of genetic variation in animals. These variances allow the animals to better adapt to their habitats.

Importance Of Variation

  • Living creatures expand their number and feed on available resources in their niche by reproducing.
  • DNA and body architecture changes may make it harder for them to survive in their environment. We are aware, however, that the environment is not consistent.
  • It varies due to changes in several elements such as climate, temperature, resource availability, and so on. If a species is too resistant to adapt during these environmental shifts, it will be unable to survive in that habitat.
  • This is where variance comes into play. Species variances enable them to adapt to their surroundings and improve their chances of survival.
Evolution and Variation


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