In short, natural selection is the process by which heritable traits that confer a survival or reproductive advantage become more common over time in a population, while traits that confer a disadvantage become less common.The process of natural selection is often described as "survival of the fittest," but this is somewhat misleading. It is not a competition in which only the strongest individuals survive; rather, it is a process by which individuals with certain heritable traits are more likely to survive and reproduce than those without those traits.Over time, the frequency of these advantageous traits will increase in the population, while the frequency of disadvantageous traits will decrease. This process can lead to the evolution of new species, as well as to the phenotypic (physical) and behavioral change within a species.