What Theory Is Tied to Evolution?


Martha Robinson

Evolution is a fascinating topic that has captivated the minds of scientists and non-scientists alike for centuries. It is the theory that explains how different species of organisms have developed and diversified over time.

However, evolution is not just a single theory but rather a collection of related theories that help to explain the process of biological change. In this article, we will explore the theory that is tied to evolution.

The Theory of Natural Selection

The theory of natural selection is perhaps the most well-known theory associated with evolution. This theory was first proposed by Charles Darwin in his book “On the Origin of Species” published in 1859. The theory explains how species evolve and adapt to their environment over time through a process called natural selection.

According to this theory, individuals within a population vary in their physical and behavioral traits. Some traits are advantageous while others are not.

Individuals with advantageous traits are more likely to survive and reproduce than those without these traits. Over time, this leads to an accumulation of advantageous traits within a population, resulting in evolutionary change.

Examples of Natural Selection

One classic example of natural selection can be seen in the coloration of peppered moths during England’s Industrial Revolution. Prior to industrialization, most peppered moths had light-colored wings which blended well with tree bark where they rested during the day.

However, as pollution from factories increased, tree bark became darkened by soot and smoke. The dark-colored moths were better camouflaged against this darker background than their lighter counterparts, making them less visible to predators. As a result, dark-colored moths became more prevalent over time.

Another example can be seen in antibiotic resistance among bacteria. Bacteria can develop resistance to antibiotics through natural selection if they possess genetic mutations that make them resistant to certain drugs.

When exposed to antibiotics, only those bacteria that are resistant will survive and reproduce, passing on their resistance genes to offspring. Over time, this can lead to the emergence of antibiotic-resistant strains of bacteria.

The Theory of Evolution by Genetic Drift

Another theory associated with evolution is the theory of genetic drift. This theory explains how random events can cause changes in the gene frequencies of a population over time, leading to evolutionary change.

Genetic drift can occur when a small population becomes isolated from the larger population and experiences different environmental conditions. In these cases, chance events such as mutations or deaths can have a greater impact on the gene pool of the smaller population due to its smaller size. Over time, this can cause genetic differences to accumulate between the two populations.

Examples of Genetic Drift

One example of genetic drift can be seen in the founder effect. The founder effect occurs when a small group of individuals becomes isolated from a larger population and forms a new colony. The gene pool of this new colony may be significantly different from that of the original population due to chance events such as mutations or deaths during migration.

Another example can be seen in genetic bottlenecks. A genetic bottleneck occurs when a large population is drastically reduced in size due to an environmental event such as a natural disaster or disease outbreak. The surviving individuals may carry only a small fraction of the original gene pool, leading to reduced genetic diversity in future generations.


In conclusion, evolution is not just a single theory but rather a collection of related theories that help explain how species change over time. The theory of natural selection explains how advantageous traits become more prevalent within a population over time while the theory of genetic drift explains how chance events can cause changes in gene frequencies within populations. These theories have provided scientists with valuable insights into how evolution works and continue to be studied and refined today.