Darwinian evolution is usually divided into macro-evolution (Greek: macro = large) and micro-evolution (Greek: micro = small).

Macro-evolution has the following characteristics:
1. it requires periods of geological time
2. it functions primarily at taxonomic levels above that of a species
3. it leads to an increased complexity
4. it produces new genetic code
5. it produces new species
6. it is irreversible

Micro-evolution is the converse in all of these characteristics:
1. it requires periods of historical time
2. it functions at taxonomic levels below that of a species
3. it does not lead to an increased complexity
4. it does not produce new genetic code; it merely rearranges existing code
5. it produces differing ecotypes
6. it is reversible

Both ancient domestication and modern plant and animal breeding involve micro-evolution. But, in each case, the micro-evolution results from artificial selection rather than natural selection. Inevitably, the distinction between the two kinds of evolution is blurred. The artificial selection produced new agro-ecotypes, although taxonomists have dignified most of them as new species with their own Latin names, particularly when polyploidy was involved. However, if left to themselves in a wild ecosystem, most agro-ecotypes would either revert to their wild form, or they would become extinct. Natural selection would undo artificial selection quite quickly, within a short period of historical time.