Evolution is defined by the change in allele frequencies over time in populations. There are various mechanisms of evolution. Naturalist Charles Darwin proposed one of these mechanisms and it is termed natural selection. These two terms, evolution and natural selection, are many times believed to be synonymous. However, the aim of this paper is to illustrate that evolution and natural selection are not synonymous both by definition and by the process it undergoes. The differences will be highlighted and the way both work together will also be clearly demonstrated. Additionally, although these terms are not synonymous, they are dependent on each other and this paper will aim to show how and why these are related but not synonymous.
To better explain why evolution and natural selection are not synonymous it is best to define them first. Evolution is the change in allele frequencies of a population from one generation to the next. There are various processes that can occur in order for populations to evolve. Natural selection is one of four processes that lead to evolution and it acts on an individual. Natural selection has three elements and the main idea is that individuals better adapted to their environment tend to survive in a population where variation and competition exist and are also able to produce viable offspring who inherit advantageous traits. Darwin’s three postulates of natural selection further explain this. Additionally, natural selection can act alone in order for evolution to occur or in can act together with any of the other three forces of evolution. Thus, in this definition it can be said that natural selection is not evolution and similarly evolution is not natural selection. Moreover, in order to enhance an understanding of why these terms are not synonymous, it is highly important to consider that natural selection acts on an individual, which is at a micro level, while evolutionary change occurs on bigger scale populations at a macro level.
Categorizing natural selection as a cause of evolution can help make a better distinction between evolution and natural selection (Stephens, 551). When viewing natural selection as one cause of evolution, it can be better be understood why these two terms are not synonymous. If one causes the other, then they cannot be the same. This observation also provides a better understanding of how these two terms are dependent of each other. If natural selection does not occur then evolution would not happen. Evolution depends on natural selection in order to occur. It is also important to clarify that given this, evolution by natural selection would not occur, however, any of the other forces of evolution would still cause evolution. Perhaps a sharper definition is that natural selection causes adaptive evolution (Gregory, 156).
One of the most common misconceptions that lead to the idea that evolution and natural selection are synonymous terms is the belief that evolution occurs in individuals as a response to environmental challenges (Gregory, 168). However, as it has been eminent by the definitions of these terms, natural selection occurs in individuals while evolution occurs in populations. Additionally, environmental factors can have an evolutionary effect, as primarily noted in Darwin’s finches. What is important to consider then is that individuals who possess an advantageous trait to survive certain environmental challenges and as a result have a high reproductive success are able to pass on the advantageous trait while individuals who don’t simply die off. Once only the descendants of the surviving individuals are left, the population can be said to have evolved (Gregory, 169). This observation thus clearly illustrates that the terms evolution and natural selection are not synonymous. They differ both by their definitions and by the mechanisms that govern each.
By clearly defining the terms evolution and natural selection, it becomes evident why these two terms are not synonymous. The differences between each concept effectively demonstrates that, although many times it can be easily mistaken for being the same, evolution and natural selection are very distinct ideas.