In the previous example, created dog breeds have less DNA variation than the ancestor population, and therefore a reduced ability to produce different dog types – let alone a different animal. No matter what breeders do, the offspring is always a dog.
Organisms also “micro-evolve” in response to environmental changes. “Darwin’s finches” are the classic case study here. During periods of dry weather, birds with longer beaks are able to reach seeds deeper in the ground and are more successful at survival and reproduction than birds with shorter beaks. Therefore, the numbers of large-beaked birds increase. As with our dogs, these adaptive changes are not the result of genetic mutation but are made possible by the existing variety of DNA information in the finch population.