Chromalveolate

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The chromalveolates (Chromalveolata) are a hypothetical grouping of eukaryotes, comprising the Chromista and alveolates, as suggested by Tom Cavalier-Smith. He argues that these groups all developed from a common ancestor with chloroplasts, acquired from a red alga. This clade is contested, since most of the more basal members (e.g. water moulds, ciliates) do not have chloroplasts and there are not many other similarities between the groups. However, the balance of molecular evidence obtained so far supports the validity of the group.

The Chromista may not be a monophyletic group, leaving four clearly valid clades within the chromalveolates:

• Cryptophyta
• Haptophyta
• Heterokonta (stramenopiles)
• Alveolata

[edit] References

• Harper, J. T., Waanders, E. & Keeling, P. J. 2005. On the monophyly of chromalveolates using a six-protein phylogeny of eukaryotes. Int. J. System. Evol. Microbiol., 55, 487-496.

• Patron, N. J., Rogers, M. B. and Keeling, P. J. 2004. Gene replacement of fructose-1,6-bisphophate aldolase supports the hypothesis of a single photosynthetic ancestor of chromalveolates. Eukaryot. Cell. 3, 1169-1174.

• Harper, J. T. & Keeling, P. J. 2003. Nucleus-encoded, plastid-targeted glyceraldehyde-3-phosphate dehydrogenase (GAPDH) indicates a single origin for chromalveolate plastids. Mol. Biol. Evol. 20, 1730-1735.

• Archibald, J. M. & Keeling, P. J. 2002. Recycled plastids: a "green movement" in eukaryotic evolution. Trends Genet., 18, 577-584.

• Fast, N. M., Kissinger, J. C., Roos, D. S., & Keeling, P. J. 2001. Nuclear-encoded, plastid-targeted genes suggest a single common origin for apicomplexan and dinoflagellate plastids. Mol. Biol. Evol., 18, 418-426.

• Cavalier-Smith, T. 1999. Principles of protein and lipid targeting in secondary symbiogenesis: Euglenoid, dinoflagellate, and sporozoan plastid origins and the eukaryote family tree. J. Eukaryot. Microbiol. 46:347–66.