What is natural selection?

Question

Natural selection: peppered moths

Answer 1

Natural Selection is part of the Theory of Evolution proposed by Charles Darwin in his well known book The Origin of Species.

The process of natural selection can be summarized as "The Survival of the Fittest."

This means that the individuals in a species who are most fit will survive.  Fitness can be measured by traits such as the ability to avoid predators, find food, and reproduce effectively as well as other similar factors.

Over time, through natural selection, traits are selected for and selected against.  Here is some information on the black peppered moth as an example of natural selection:

The evolution of the peppered moth over the last two hundred years has been studied in detail. Originally, the vast majority of peppered moths had light coloration, which effectively camouflaged them against the light-colored trees and lichens which they rested upon. However, because of widespread pollution during the Industrial Revolution in England, many of the lichens died out, and the trees that peppered moths rested on became blackened by soot, causing most of the light-colored moths, or typica, to die off from predation. At the same time, the dark-colored, or melanic, moths, carbonaria, flourished because of their ability to hide on the darkened trees.

Answer 2

Natural selection is the process that leads to adaptation and to diversity of life on earth. The idea is both very simple and incredibly complex. In any species of organisms, there are genetic variations. Some of these variations lead to a greater ability to survive and or reproduce. The next generation will have a greater proportion of individuals with those variations which produced better survival and reproduction. Over time, the population of organisms will change as a result of natural selection.

 

In the case of the peppered moths, as soot covered things, the rare dark variants didn't get eaten by predators as much as the other moths did, and so survived better to reproduce. Over several generations, the dark moths became the most common form.