Phylogenetic classification

Phylogenetic classification arranges species into groups according to their evolutionary origins and relationships. Species with a more recent shared evolutionary origin are placed in more specific groups together.

Each group in the classification is called a taxon; the plural is taxa. Taxa form a hierarchy: smaller groups are nested within larger groups. For example, a genus contains one or more species, and a family contains one or more genera.

Ranks in the phylogenetic hierarchy

From the broadest rank to the most specific, the hierarchy is:

Domain → kingdom → phylum → class → order → family → genus → species

Each successive rank divides organisms into more specific groups. A species belongs within a genus, that genus belongs within a family, and so on up to a domain.

Groups at the same rank do not overlap. For example, a species cannot belong to two different genera in the same classification. Different genera can, however, be nested within the same family.