What is Domain (biology)?
[[File:Biological_classification_L_Pengo.svg|right|144px|The hierarchy of scientific classification]] In [[Biology|biological]] [[taxonomy]], a '''domain''' (also '''superregnum''', '''superkingdom''', or '''empire''') is a [[taxon]] in the highest [[rank]] of [[organism]]s, higher than a [[Kingdom (biology)|kingdom]]. Domain (or its [[synonym]]s) is the most inclusive of these biological groupings. The arrangement of taxa reflects the fundamental evolutionary differences in the [[genome|genomes.]] There are several modern alternative domain classifications of [[life]]. Among them are: * The 'two-empire' system, with top-level groupings of [[Prokaryota]] (or [[Monera]]) and [[Eukaryota]] empires. * The [[Kingdom (biology)#Six kingdoms|six-kingdom system]] with top-level groupings of [[Protista]], [[Archaebacteria]], [[Eubacteria]], [[Fungi]], [[Plantae]], and [[Animal]]ia. * The '''three-domain system''' of [[Carl Woese]], introduced in 1990, with top-level groupings of [[Archaea]], [[Bacteria]], and [[Eukaryota]] domains. After defining Archaea as a new domain, Woese redrew the [[taxonomy|taxonomic]] tree. His three-domain system is based upon [[genetic]] relationships. 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 are [[prokaryote]]s that are not bacteria. [[File:3_domains_of_life.png|thumb|center|400px|The three domains]] ==Related pages== * [[Phylogenetics]] * [[Taxonomy]] [[Category:Taxonomy]]