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SUPERGROUP CHROMALVEOLATA

The Chromalveolata includes three kingdoms: Heterokontae, Alveolatae, and Eukaryomonadae whose taxa may be photosynthetic, parasitic, saprophytic, or heterotrophic.  They range in form from unicells to some of the largest multicellular organisms on earth.  Photosynthetic cells within this supergroup tend to use chlorophylls a and c, a characteristic that served to associate them through much of the 20th Century.

  Pascher (1914) united many of the photosynthetic taxa with other nonphotosynthetic taxa on the basis of their distinctive motile cells: biflagellate with an anteriorly-directed tinsel flagellum and a posteriorly-directed  (recurrent) whiplash flagellum.  Informally, they were called the chromophytes (literally meaning colored plants), because the photosynthetic taxa were colors other than green (e.g. brown, golden, etc.).  Christensen (1962) formally defined the Division (a Botanical hierarchical name that approximately equals a phylum) and named it Chromophyta.  Later, Cavalier-Smith (1989) created the Kingdom Chromista, a taxon that contained all of the heterokonts and eukaryomonads.  Then, the alveolates began to come together as a group based on speculation by Taylor (1976) and later by Gajadhar et al. (1991).  The association between the heterokonts and alveolates developed from 1999-2005 (Taylor, 1999; Patterson, 1999; Baldauf, 2003; Keeling, 2004; and Harper et al., 2005).  Harper et al. (2005) show convincing evidence that the heterokont+alveolate clade is monophyletic and weakly associated with the eukaryomonads.

At present, the chromalveolates do not seem to have a defining synapomorphy.  Table 1 shows three common characters (photosynthesis, cell covering, and flagella) in the whole supergroup.

For further information, go to the Evolution of the Eukaryotic Supertree.

REFERENCES.

This page is maintained by Jack R. Holt-Carlos A. Iudica: 04/22/2008