The Full Wiki

Rhizaria: Wikis

Advertisements
  
  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

From Wikipedia, the free encyclopedia

Rhizaria
Fossil range: Neoproterozoic - Recent
Live Ammonia tepida (Foraminifera)
Scientific classification
Domain: Eukarya
Kingdom: Rhizaria
Cavalier-Smith, 2002
Phyla

Cercozoa
Retaria

Foraminifera
Radiolaria

The Rhizaria are a species-rich supergroup of unicellular[1]eukaryotes.[2] They vary considerably in form, but for the most part they are amoeboids with filose, reticulose, or microtubule-supported pseudopods. Many produce shells or skeletons, which may be quite complex in structure, and these make up the vast majority of protozoan fossils. Nearly all have mitochondria with tubular cristae.

Contents

Groups

There are three main groups of Rhizaria:[3]

  • Cercozoa - Various amoebae and flagellates, usually with filose pseudopods and common in soil

A few other groups may be included in the Cercozoa, but on some trees appear closer to the Foraminifera. These are the Phytomyxea and Ascetosporea, parasites of plants and animals respectively, and the peculiar amoeba Gromia. The different groups of Rhizaria are considered close relatives based mainly on genetic similarities, and have been regarded as an extension of the Cercozoa. The name Rhizaria for the expanded group was introduced by Cavalier-Smith in 2002,[4] who also included the centrohelids and Apusozoa.

Evolutionary relationship

Rhizaria is part of the bikont clade, which also comprises the Archaeplastida, the Chromalveolata, the Excavata, and some smaller, unresolved groups such as the Apusozoa and the Centrohelida. As bikonts, they all descend from a heterotrophic eukaryote with two flagella.

Historically, many rhizarians were considered animals, with their motility and heterotrophy as justification. However, when the five-kingdom system took prevalence over the animal-plant dichotomy, the rhizarians were put into the kingdom Protista. Then, after Woese published his three-domain system, because of the paraphyly of the kingdom Monera, taxonomists turned their attention to the eukaryote domain, and the inherent paraphyly of Protista. After much debate, which continues to this day, Rhizaria emerged as a monophyletic group.[5]

References

  1. ^ Christopher Taylor (2004). "Rhizaria". http://www.palaeos.com/Eukarya/Units/Rhizaria/Rhizaria.html.  
  2. ^ Nikolaev SI, Berney C, Fahrni JF, et al. (May 2004). "The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes". Proc. Natl. Acad. Sci. U.S.A. 101 (21): 8066–71. doi:10.1073/pnas.0308602101. PMID 15148395. PMC 419558. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=15148395.  
  3. ^ Moreira D, von der Heyden S, Bass D, López-García P, Chao E, Cavalier-Smith T (July 2007). "Global eukaryote phylogeny: Combined small- and large-subunit ribosomal DNA trees support monophyly of Rhizaria, Retaria and Excavata". Mol. Phylogenet. Evol. 44 (1): 255–66. doi:10.1016/j.ympev.2006.11.001. PMID 17174576. http://linkinghub.elsevier.com/retrieve/pii/S1055-7903(06)00433-7.  
  4. ^ Cavalier-Smith, Thomas (2002). "The phagotrophic origin of eukaryotes and phylogenetic classification of Protozoa". International Journal of Systematic and Evolutionary Microbiology 52 (2): 297–354. ISSN 1466-5026. PMID 11931142. http://ijs.sgmjournals.org/cgi/content/abstract/52/2/297. Retrieved 2007-06-08.  
  5. ^ Fabien, F; Shalchian-Tabrizi, K; Minge, M; Skjaeveland, A; Nikolaev, SI; Jakobsen, KS; Pawlowski, J (2007). "Phylogenomics Reshuffles the Eukaryotic Supergroups". PLoS ONE 2 (8): e790-. doi:10.1371/journal.pone.0000790. PMID 17726520. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0000790. Retrieved 2008-01-24.  

External links

Advertisements

Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

Contents

Translingual

Etymology

Proper noun

Rhizaria

  1. (taxonomy) A taxonomic infrakingdom within the subkingdom Biciliata — many protists.

Hyponyms

See also


Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Rhizaria
Phyla: Cercozoa - Haplosporidia - Retaria - Incertae sedis

References

  • Archibald, J.M.; Keeling, P.J. 2004: Actin and ubiquitin protein sequences support a cercozoan/foraminiferan ancestry for the plasmodiophorid plant pathogens. Journal of eukaryotic microbiology, 51(1): 113-118. [1]
  • Cavalier-Smith, T. 2003: Protist phylogeny and the high-level classification of Protozoa. European journal of protistology, 39: 338-348.

Advertisements






Got something to say? Make a comment.
Your name
Your email address
Message