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What is Natural Selection – Principles, Types and FAQs

Jul 7, 2022

Natural Selection 

The theory of natural selection is one of Charles Darwin’s most important contributions to the field of evolution. According to the hypothesis, individuals of a population contend with each other for resources, and those more suited to their habitat have a higher chance of survival. It was not recognised for many decades after Darwin offered it. Natural selection is the foundation for our knowledge of how species evolve through time.

What is Natural Selection?

Natural selection is defined as the method by which populations of organisms adapt and evolve. Individuals within a population are naturally diverse, which means they differ in certain respects. This variation implies that some people have more adapted qualities to their environment than others.


Have you ever seen a giraffe? Giraffes’ long necks allow them to dine on leaves that others cannot, giving them a significant edge. Because of a richer food source, individuals with longer necks could procreate and pass on the trait to the next generation. Others with shorter necks and limited nutritious food are less likely to survive and transmit their genetic materials. 

Principles of Natural Selection 

The meaning of natural selection is the process through which organisms better suited to their surroundings tend to thrive and generate more offspring. Natural selection is a primary mechanism that generates changes in the populations of living organisms over time. It has five main steps: variation, inheritance, selection, time, and adaptation.


1. Variation and Inheritance

Members of any particular species are seldom identical, either inside or out. Organisms differ in size, colour, disease resistance, and various other characteristics. Such variety is frequently the consequence of random mutations or “copying mistakes” that occur as cells split to form new creatures.

When creatures reproduce, they pass on their DNA to their children (the genetic information responsible for an organism’s growth and function in living cells). Because many features are encoded in DNA, offspring frequently inherit their parents’ variants. Tall adults, for example, are more likely to have tall offspring.


2. Selection: Survival and Reproduction

Environments cannot sustain an infinite number of people. Resources are scarce, but more creatures are born than can survive. However, some organisms will be more effective at obtaining food, mating, or escaping predators, giving them a greater opportunity to live, breed, and carry on their DNA.

Small differences can determine if an organism lives and creates more progeny. Colour differences, for example, benefit certain species in concealing them from predators. Sharper eyes and talons aid an eagle in catching its prey. A male peacock’s prospects of finding a partner rise with a brighter colour.


3. Time and Adaptation

Beneficial features enable certain people to live and reproduce generation after generation. These characteristics are, in turn, handed on to an increasing number of offspring. Depending on conditions, such features become widespread within a few generations or thousands. As a result, the population is more suited—or adapted—to some environmental features than it was previously. Legs formerly utilised for walking are now used as wings or flippers. The colours of the scales used for protection shift to function as camouflage.

Types of Natural Selection 

What is natural selection? It is a method for populations to evolve and develop favourable adaptations. Three forms of selection can occur in natural selection. Among these are the following:


Stabilizing Selection 

This form of natural selection occurs when natural forces act against two extreme poles of a characteristic, causing the intermediate or “middle” feature to be selected. When we examine the population’s characteristics distribution, we can see that a standard distribution is followed. 

For example, towering plants are overexposed to wind and are more likely to be swept away. Plants that are too short do not receive enough sunlight to thrive. As a result, plants between the two in height receive adequate sunshine and wind protection.


Directional Selection 

When selective forces favour one extreme of a characteristic, this sort of natural selection arises. As a result, when examining the dispersion of characteristics in a population, a graph heavily favours one side. 

For example, giraffes with the longest necks can reach more leaves. Directional selection pressures will favour the longer-neck giraffes, so the frequency of the trait among the population will change in favour of the longer-neck phenotype.


Disruptive Selection 

This form of natural selection arises when selective forces favour the two extremes while opposing the middle characteristic. This kind of selection is less typical. When examining a trait distribution, there are two higher peaks on either end, with a nadir in the middle.

For example, in a region with black, white, and grey rabbits, there are black and white rocks. Natural selection will favour white and black characteristics since they are good for concealment. Because the intermediate feature of grey is not as valuable, selected forces operate against it.

Natural Selection Examples

1. Darwin’s Finches 

Once the definition of natural selection is clear, it’s imperative to look at some important examples. Darwin’s finches are one such example.

Darwin examined the Galapagos flora and wildlife. It is an island chain off the shore of America’s west coast. He saw a variety of fascinating species there. He discovered many different types of birds on these islands, with the primary differences being the form of their beaks and their foraging preferences. These little blackbirds were eventually dubbed Darwin finches.

He recognised after examining them that all of these types originated on the same island and were not from different places. He concluded that these variations descended from the original seed-eating progenitor bird found in South America. However, Finches developed in response to varied food sources, with sharp, pointed beaks ideal for capturing insects and broad, blunt beaks ideal for breaking seeds and nuts.

2. Peppered Moths 

Until the early 1800s, most peppered moths were of the pale form. This showed that they were disguised against the pale birch trees where they were resting. Birds immediately identified and ate mutant black-coloured moths. During the second part of the nineteenth century, soot from airborne pollutants in industrial districts darkened the bark of birch trees. This benefited the black type since they were more likely to live and reproduce. Black peppered moths have become significantly more abundant in urban areas than the pale variant. 

It should be highlighted that the phenotypic shift was not caused by pollutants making the moths darker. The dark variety remained, but it became the more suited kind when the environment changed. It took several years for the moth population to be primarily black. 

What are the benefits and drawbacks of Darwin’s theory?

Natural selection can only function on the variance that already exists within a species. Such variances are caused by mutation, which is a modification in some element of a trait’s genetic code. Mutations occur by accident and without regard for the mutation’s possible benefit or disadvantage. In other words, variants don’t appear because they’re required.

The advantages of natural selection are as follows: 

  1. Beneficial qualities are passed down across generations through the process of natural selection. 
  2. Speciation is a normal consequence of natural selection, where one species produces a new and separate species. 
  3. It is one of the mechanisms that drive evolution and contributes to the diversity of life on Earth.

Although it is a theory that has become very popular recently, it is not without limitations. The following are some of the drawbacks of the natural selection theory: 

  1. Even though his theory is founded on the presence of variants, he could not explain the genesis of variation or assign any significance to mutations.
  2. Darwin was unable to explain the emergence of new characteristics. It just provides a way for changing existing characters.
  3. Over-specialized organs are those that have outgrown their function. They have become a barrier to the animal, such as branching antlers of deer, elephant tusks, and so on. 


Natural selection contributes to the diversity of life on Earth. Understanding how these ecological processes operate at the population level is crucial for biodiversity conservation. Natural selection has been predicted in the short term by scientists. However, due to unforeseen environmental swings, predicting its future impacts is nearly difficult.

Natural selection suggests that organisms are adapted if they survive. However, if the environment changes, what was previously an adaptation may no longer be helpful. Although fast evolution is feasible, the more rapidly the world changes, the more difficult it is for evolution to keep up, and the greater the chance of mass extinction increases.

Frequently Asked Questions About Natural Selection

1. What is natural selection? Give an example of evolution by natural selection. 

 Natural selection is the process in which more environment-adapted organisms tend to flourish, thrive and breed more frequently than less environment-adapted ones. For example, finches with bigger beaks fared better during droughts than finches with smaller beaks. However, smaller seeds were generated during wet seasons, and finches with smaller beaks survived longer.

2. What are the main principles of natural selection?

Natural selection means ‘survival of the fittest.’ Thus Darwin’s process of natural selection has four components. They are (1) Variation, (2) Inheritance, (3) Selection, and (4) Time.

3. What is the importance of natural selection?

Natural selection has several advantages in terms of creating new species. They are enlisted below:

  • The variations arise in the inheritable genotype. It improves one’s chances of surviving.
  • It results in the emergence of new species.
  • It increases good mutations and removes bad ones over generations.
  • The organisms have improved their adaptation to physiological and biological settings.
Natural Selection


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