In this post, we’ll unpack all you need to know about Natural Selection, defining exactly what it is, the science behind how it works and more.
What Is Natural Selection?
Natural Selection is the adaptive evolutionary process organisms go through in response to change in their environment.
While Natural Selection occurs over a single generation, evolution occurs over many generations.
“Nothing in biology makes sense except in light of evolution.” ― Theodosius Dobzhansky
3 Key Ingredients
Natural Selection requires three key ingredients.
Firstly, there needs to be random variation among the progeny of an organism. The important to note the word “random.” Variation does not seek any goal.
Secondly, there needs to be differential fitness among these variants such that injurious variations get rejected and favourable ones are preserved.
Thirdly, the favourable traits must be heritable so that they are passed on to the next generation.
The Science Behind How Natural Selection Works
Natural Selection is the engine that drives evolution.
Organisms in any population are naturally variable in the sense that they are different. This means that some organisms are better adapted to their environment than others.
Organisms with traits that are more adapted to their environment are more likely to survive and reproduce. As a result, these advantageous traits succeed in being passed on to the next generation and thus become more common.
Organisms with traits that are less adapted to their environment are less likely to survive and reproduce. As a result, these disadvantageous traits fail in being passed on to the next generation and thus become less common.
Natural Selection can lead to speciation. Therefore, one species can give rise to a completely new and distinctly different species which helps explain the diversity of life on Earth.
Adaptations
Adaptation are solutions to problems posed by survival and reproduction. Humans evolved mental, emotional and physical adaptations.
Problems that adaptations allow us to solve are called adaptive problems ― problems of survival and reproduction. Thus, without solving adaptive problems, we would not be able to survive long enough to reproduce successfully.
Mutations
Mutations are changes in the structure of the molecules that make up genes, called DNA. They are either harmful, neutral or helpful.
Mutations can either occur randomly ― for example when replicating cells make an error while copying DNA ― or in response to the environment ― for example radiation.
Genes that increase an organisms chances of survival and reproduction are thus passed on to the next generation at the expense of those that don’t.
Natural Selection Versus Sexual Selection
Natural Selection is the evolution of qualities that enhance survival. Sexual Selection is the evolution of qualities that enhance reproduction.
Summary (TL;DR)
Natural Selection is the evolutionary process by which organisms change and adapt over time in response to the environment.
Traits that enhance an organisms ability to survive and reproduce are thus selected for and increase in frequency. Traits that decrease an organisms ability to survive and reproduce are thus selected against and decrease in frequency.
