The Taxonomy Database is a curated classification and nomenclature for all of the organisms in the public sequence databases. This currently represents about 10% of the described species of life on the planet.
The Entrez Taxonomy database displays the species names (and higher-level classification) of all of the organisms that are represented in the Entrez sequence databases (or any of the other Entrez databases that are indexed by taxonomy).
Species that have not yet appeared in public entries in another Entrez database will not appear in Entrez Taxonomy.
The Entrez Taxonomy database is curated by a small group of taxonomists at the NCBI, based on the current consensus classification in the systematic literature. We try to maintain a phylogenetic classification (containing only monophyletic groups, whenever possible) but it is not automatically generated from the sequence data itself. Although there are a growing number of species with complete genomes in GenBank, the vast majority of species in Entrez Taxonomy are represented by a small snippet of sequence data, not sufficient to construct a robust phylogeny.
September 13, 2010