Domain (biology)
Inbiologicaltaxonomy,adomain(alsosuperregnum,superkingdom,orempire) is ataxonin the highestrankoforganisms,higher than akingdom.
Domain (or itssynonyms) is the most inclusive of these biological groupings. The arrangement of taxa reflects the fundamental evolutionary differences in thegenomes.There are several modern alternative domain classifications oflife.Among them are:
- The 'two-empire' system, with top-level groupings ofProkaryota(orMonera) andEukaryotaempires.
- Thesix-kingdom systemwith top-level groupings ofProtista,Archaebacteria,Eubacteria,Fungi,Plantae,andAnimalia.
- Thethree-domain systemofCarl Woese,introduced in 1990, with top-level groupings ofArchaea,Bacteria,andEukaryotadomains.
After defining Archaea as a new domain, Woese redrew thetaxonomictree. His three-domain system is based upongeneticrelationships. It divides life into 23 main divisions in three domains: Bacteria, Archaea, and Eukarya. Archaea are neither bacteria nor eukaryotes. Looked at another way, they areprokaryotesthat are not bacteria.
