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The Chromista is a eukaryotic supergroup, probably polyphyletic,[1][2] which may be treated as a separate kingdom or included among the Protista. They include all algae whose chloroplasts contain chlorophylls a and c, as well as various colorless forms that are closely related to them. These chloroplasts are surrounded by four membranes, and are believed to have been acquired from some red algae.

Chromista
Scientific classification
Domain: Eukaryota
(unranked): Diaphoretickes
Kingdom: Chromista
Phyla

Contents

GroupsEdit

Chromista has been defined in different ways at different times. The name Chromista was first introduced by Cavalier-Smith in 1981;[3] the earlier names Chromophyta, Chromobiota and Chromobionta correspond to roughly the same group.

It has been described as consisting of three different groups:[4]

In 2010, Thomas Cavalier-Smith indicated his desire to move Alveolata, Rhizaria and Heliozoa into Chromista.[5]

Some examples of classification of the Chromista and related groups are shown below.[6][7]

Chromophycées (Chadefaud, 1950)Edit

The Chromophycées (Chadefaud, 1950),[8] renamed Chromophycota (Chadefaud, 1960),[9] included the current Ochrophyta (autotrophic Stramenopiles), Haptophyta (included in Chrysophyceae until Christensen, 1962), Cryptophyta, Dinophyta, Euglenophyceae and Choanoflagellida (included in Chrysophyceae until Hibberd, 1975).

Chromophyta (Christensen 1962, 1989)Edit

The Chromophyta (Christensen 1962, 1989), defined as algae with chlorophyll c, included the current Ochrophyta (autotrophic Stramenopiles), Haptophyta, Cryptophyta, Dinophyta and Choanoflagellida. The Euglenophyceae were transferred to the Chlorophyta.

Chromophyta (Bourrelly, 1968)Edit

The Chromophyta (Bourrelly, 1968) included the current Ochrophyta (autotrophic Stramenopiles), Haptophyta and Choanoflagellida. The Cryptophyceae and the Dinophyceae were part of Pyrrhophyta (= Dinophyta).

Chromista (Cavalier-Smith, 1981)Edit

The Chromista (Cavalier-Smith, 1981) included the current Stramenopiles, Haptophyta and Cryptophyta.

Chromalveolata (Adl et al., 2005)Edit

The Chromalveolata (Cavalier-Smith, 1981) included Stramenopiles, Haptophyta, Cryptophyta and Alveolata.

Chromista (Cavalier-Smith, 2010)Edit

The Chromista (Cavalier-Smith, 2010) included SAR (Stramenopiles, Alveolata and Rhizaria) and Hacrobia (Haptista, Cryptista). A new classification of classes and phyla within Chromista was proposed by Cavalier-Smith in 2017.[10]

PhylogenyEdit

Chromista
Hacrobia
Cryptista

Corbihelia Cavalier-Smith 2015



Cryptophyta Silva 1962



Haptista

Centroheliozoa Cushman & Jarvis 1929 sensu Durrschmidt & Patterson 1987



Haptophyta Hibberd 1976 emend. Edvardsen & Eikrem 2000




SAR supergroup
Rhizaria

Phytomyxea Engler & Prantl 1897 em. Cavalier-Smith 1993




Vampyrellidea Cavalier-Smith 2017




Filosa Leidy 1879 emend. Cavalier-Smith 2003 stat. nov.



Retaria Cavalier-Smith 1999 emend. Cavalier-Smith 2017





Halvaria
Alveolata

Ciliophora Doflein 1901 stat. n. Copeland 1956



Miozoa Cavalier-Smith 1987



Heterokonta

Platysulcea Cavalier-Smith 2017




Sagenista Cavalier-Smith 1995 stat. n. 2006




Bikosea Cavalier-Smith 2013




Placidozoa Cavalier-Smith 2013


Gyrista

Bigyromonadea Cavalier-Smith 1998




Peronosporomycota Dick 1995




Hyphochytriomycota Whittaker 1969




Pirsonea Cavalier-Smith 2017



Ochrophyta Cavalier-Smith 1986













History and controversyEdit

Molecular trees have had some difficulty resolving relationships between the different groups. All three may share a common ancestor with the alveolates (see chromalveolates), but there is evidence that suggests that the haptophytes and cryptomonads do not belong together with the heterokonts or the SAR clade, but may be associated with the Archaeplastida.[1][11]

See alsoEdit

ReferencesEdit

  1. ^ a b Laura Wegener Parfrey; Erika Barbero; Elyse Lasser; Micah Dunthorn; Debashish Bhattacharya; David J Patterson & Laura A Katz (December 2006). "Evaluating Support for the Current Classification of Eukaryotic Diversity". PLoS Genet. 2 (12): e220. doi:10.1371/journal.pgen.0020220. PMC 1713255 . PMID 17194223. 
  2. ^ Cavalier-Smith T, Allsopp MT, Chao EE (November 1994). "Chimeric conundra: are nucleomorphs and chromists monophyletic or polyphyletic?". Proc. Natl. Acad. Sci. U.S.A. 91 (24): 11368–72. doi:10.1073/pnas.91.24.11368. PMC 45232 . PMID 7972066. 
  3. ^ T. Cavalier-Smith (1981). "Eukaryote kingdoms: seven or nine?". Biosystems. 14 (3–4): 461–481. doi:10.1016/0303-2647(81)90050-2. PMID 7337818. 
  4. ^ Csurös M, Rogozin IB, Koonin EV (May 2008). "Extremely intron-rich genes in the alveolate ancestors inferred with a flexible maximum-likelihood approach". Mol. Biol. Evol. 25 (5): 903–11. doi:10.1093/molbev/msn039. PMID 18296415. 
  5. ^ Cavalier-Smith T (June 2010). "Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree". Biol. Lett. 6 (3): 342–5. doi:10.1098/rsbl.2009.0948. PMC 2880060 . PMID 20031978. 
  6. ^ Reviers, B. de. (2006). Biologia e Filogenia das Algas. Editora Artmed, Porto Alegre, pp. 156-157.
  7. ^ W. H. Blackwell (2009). Chromista revisited: A dilemma of overlapping putative kingdoms, and the attempted application of the botanical code of nomenclature. Phytologia 91(2).
  8. ^ Chadefaud, M. 1950. Les cellules nageuses des Algues dans l'embranchement des Chromophycées. Comptes rendus hebdomadaire de l'Académie des Sciences, Paris 231: 788–790.
  9. ^ Chadefaud, M. 1960. Les végétaux non vasculaires (Cryptogamie). In Chadefaud, M., and Emberger, L. Traité de Botanique Systématique. Tome I. Paris.
  10. ^ Cavalier-Smith, T. (September 2017). "Kingdom Chromista and its eight phyla: a new synthesis emphasising periplastid protein targeting, cytoskeletal and periplastid evolution, and ancient divergences". Protoplasma: 1–61. doi:10.1007/s00709-017-1147-3. 
  11. ^ Burki F, Shalchian-Tabrizi K, Minge M, et al. (2007). Butler G, ed. "Phylogenomics Reshuffles the Eukaryotic Supergroups". PLoS ONE. 2 (8): e790. doi:10.1371/journal.pone.0000790. PMC 1949142 . PMID 17726520. 

External linksEdit