How Does Natural Selection Work?Natural selection is the process by which species evolve over time. Individuals inherit traits, or features, from their parents. No two organisms (except identical twins) are exactly alike genetically. This is called individual variation. Inherited variation comes from the mixture of genetic information from parents, and very occasionally from new mutations (copying errors of DNA).
Those individuals with traits that allow them to survive better will tend to pass those characteristics to their offspring. Such traits may eventually become common in the population. Over time, populations may become so different from each other that they can no longer breed together—becoming separate species.