What Is Part of the Theory of Evolution by Natural Selection?


Vincent White

Evolution by natural selection is a scientific theory that helps to explain how different species arise and change over time. It is based on the idea that organisms that are better adapted to their environment are more likely to survive and reproduce, passing on their advantageous traits to future generations.

But what exactly is part of this theory? Let’s dive into it.

Genetic Variation

One of the key components of natural selection is genetic variation. This refers to the differences in DNA sequences among individuals within a population. These variations arise through mutations, which can be beneficial, harmful, or have no effect at all.

Beneficial mutations are those that confer an advantage in a particular environment, such as resistance to a disease or an ability to obtain food more efficiently.

Harmful mutations, on the other hand, can decrease an individual’s chances of survival and reproduction.

Selection Pressures

Natural selection occurs when there is a selection pressure, or an environmental factor that affects the survival and reproduction of individuals within a population. These pressures can be biotic (such as competition for resources or predation) or abiotic (such as temperature or rainfall).

Individuals with advantageous traits are more likely to survive and reproduce in their environment, passing those traits on to their offspring. Over time, these traits become more common in the population as a whole.


As advantageous traits become more common within a population over generations, they can lead to adaptation, which is the process by which populations become better suited to their environment.

For example, if a population of birds lives in an area with short trees and little ground cover, those birds with longer beaks may have an advantage in reaching food sources. Over time, this trait would become more common in the population, leading to the evolution of a new species adapted to that particular environment.


Over time, these gradual changes in populations can accumulate and lead to the formation of new species through a process called speciation. This occurs when populations become so different from each other that they can no longer interbreed and produce viable offspring.

For example, if a population of birds becomes geographically isolated from another population and experiences different selection pressures, they may evolve in different directions until they are unable to mate with each other. This would result in the formation of two distinct species.


Evolution by natural selection is a complex theory that involves genetic variation, selection pressures, adaptation, and speciation. It helps us understand how different species arise and change over time in response to their environment. By studying this theory, we can gain a greater appreciation for the amazing diversity of life on our planet.