In the wild, species are constantly changing, although it is usually difficult to see the change because this happens so very slowly. The basis for the evolution of species is that mutations occur in the genomic DNA of an organism. This is constantly happening in all organisms. Most of these mutations are repaired or insignificant. However, some mutations persist and affect the survival and progeny of individuals.

The picture below shows a white peacock. It has a mutation in its genome that prevents the development of coloured feathers. When the mutation is also present in the germ cells, it will be passed onto offspring.

The peacock's feathers do not produce colour pigment as a result of a genetic mutation.

Harmful mutations disappear because only individuals carrying the mutation precede poorly. If the mutation is favorable, eg. protects the organism against predator or helps them survive the winter, it will be passed on to the next generation. In this way, species become slightly different from generation to generation. The elimination of harmful traits and the passing on favourable traits to the next generation is called natural selection. Over time this process allows organisms to adapt to their environment.

How can new species arise from existing species? For species to separate from one another, different reproductive barriers, which prevent mating or reproduction of viable, fertile offspring, are formed. This may happen, for example, if one part of a previously unified population is isolated from the other parts of the populations. As there is no contact between these two populations, they can then gradually evolve in different directions. Over time, the differences become so great that individuals of different populations can no longer reproduce with each other. When this happens, a new species has emerged.