All individuals within one species have different variations of inherited genes (DNA). This variation creates both visible and invisible differences between individuals. Genetic variation is the source for e.g. different skin, eye and hair colour in humans. Invisible effects of variation are for example different tolerance for pollution and resistance against diseases.
The genetic variation is the species insurance. It gives them the ability to adapt to various living conditions. When the environment changes, some individuals will be better adapted and have better chances of surviving. These will then ensure the survival of the species. A species with little genetic variation will be more vulnerable to a changing environment.
In the long run is the genetic variation and adaptability to new environments the basis for the development of new species.
