Hacrobia

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The cryptomonads-haptophytes assemblage is a proposed monophyletic grouping[1] of chromalveolata that are not included in the SAR supergroup. Several alternative names have been used for the group, including Hacrobia (derived from "ha-" referring to Haptophyta, "-cr-" referring to cryptomonads, and "-bia" as a general suffix referring to life);[2] CCTH (standing for Cryptophyta, Centrohelida, Telonemia and Haptophyta);[3] and "Eukaryomonadae".[4]

As of February 2012, it is unclear whether this group is monophyletic or not; results of phylogenetic studies are "often dependent on the selection of taxa and gene data set".[3] Two 2012 studies produced opposite results.[5][3]

Members[edit]

In the past, heterokonts, haptophytes, and cryptomonads have sometimes been grouped together in a group known as chromists.[6] Though the heterokonts are now split out, Cryptophyta and Haptophyta are considered in some studies to be closely related[7][8] (and are sometimes simply referred to as the "Cryptophyta+Haptophyta" group).[9] A 2009 paper suggested that the Telonemia and centrohelids may form a clade with the cryptophytes and haptophytes.[10] The picobiliphytes may belong in this group but are too poorly known to be classified with confidence.[2]

Several recent studies have concluded that Haptophyta and Cryptophyta do not form a monophyletic group.[11] The former are a sister group to the SAR group, the latter cluster with the Archaeplastida (plants in the broad sense).[5] As of February 2012, it remains unclear whether the Hacrobia forms a monophyletic group.[3]

References[edit]

  1. ^ Sakaguchi M, Takishita K, Matsumoto T, Hashimoto T, Inagaki Y (July 2009). "Tracing back EFL gene evolution in the cryptomonads-haptophytes assemblage: separate origins of EFL genes in haptophytes, photosynthetic cryptomonads, and goniomonads". Gene 441 (1-2): 126–31. doi:10.1016/j.gene.2008.05.010. PMID 18585873. 
  2. ^ a b Okamoto, N.; Chantangsi, C.; Horák, A.; Leander, B.; Keeling, P.; Stajich, J. E. (2009). Stajich, Jason E., ed. "Molecular Phylogeny and Description of the Novel Katablepharid Roombia truncata gen. et sp. nov., and Establishment of the Hacrobia Taxon nov". PLoS ONE 4 (9): e7080. Bibcode:2009PLoSO...4.7080O. doi:10.1371/journal.pone.0007080. PMC 2741603. PMID 19759916.  edit
  3. ^ a b c d Zhao, Sen; Burki, Fabien; Bråte, Jon; Keeling, Patrick J.; Klaveness, Dag; Shalchian-Tabrizi, Kamran (2012). "Collodictyon—An Ancient Lineage in the Tree of Eukaryotes". Molecular Biology and Evolution 29 (6): 1557–68. doi:10.1093/molbev/mss001. PMC 3351787. PMID 22319147. Retrieved 2012-03-02. 
  4. ^ "EUKARYOMONADAE". Retrieved 2010-07-19. 
  5. ^ a b Burki, F.; Okamoto, N.; Pombert, J.F. & Keeling, P.J. (2012). "The evolutionary history of haptophytes and cryptophytes: phylogenomic evidence for separate origins". Proc. Biol. Sci. doi:10.1098/rspb.2011.2301. 
  6. ^ 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. 
  7. ^ Rice DW, Palmer JD (2006). "An exceptional horizontal gene transfer in plastids: gene replacement by a distant bacterial paralog and evidence that haptophyte and cryptophyte plastids are sisters". BMC Biol. 4: 31. doi:10.1186/1741-7007-4-31. PMC 1570145. PMID 16956407. 
  8. ^ Aharon Oren; R. Thane Papke (1 July 2010). Molecular Phylogeny of Microorganisms. Horizon Scientific Press. pp. 190–. ISBN 978-1-904455-67-7. Retrieved 21 January 2011. 
  9. ^ Reeb VC, Peglar MT, Yoon HS, et al. (May 2009). "Interrelationships of chromalveolates within a broadly sampled tree of photosynthetic protists". Mol. Phylogenet. Evol. 53 (1): 202–11. doi:10.1016/j.ympev.2009.04.012. PMID 19398025. 
  10. ^ Burki, F; Inagaki, Y; Bråte, J; Archibald, J.; Keeling, P.; Cavalier-Smith, T; Sakaguchi, M; Hashimoto, T; Horak, A; Kumar, S; Klaveness, D; Jakobsen, K.S; Pawlowski, J; Shalchian-Tabrizi, K (2009). "Large-scale phylogenomic analyses reveal that two enigmatic protist lineages, Telonemia and Centroheliozoa, are related to photosynthetic chromalveolates." (Free full text). Genome Biology and Evolution 1: 231–8. doi:10.1093/gbe/evp022. PMC 2817417. PMID 20333193. 
  11. ^ Baurain, Denis; Brinkmann, Henner; Petersen, Jörn; Rodríguez-Ezpeleta, Naiara; Stechmann, Alexandra; Demoulin, Vincent; Roger, Andrew J.; Burger, Gertraud; Lang, B. Franz & Philippe, Hervé (2010), Phylogenomic Evidence for Separate Acquisition of Plastids in Cryptophytes, Haptophytes, and Stramenopiles, Molecular Biology and Evolution 27 (7): 1698–1709, doi:10.1093/molbev/msq059 

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