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Rhizaria

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Rhizaria
Ammonia tepida(Foraminifera)
Scientific classificationEdit this classification
Domain: Eukaryota
Clade: Diaphoretickes
Clade: TSAR
Clade: SAR
Clade: Rhizaria
Cavalier-Smith,2002
Phyla[2]

TheRhizariaare a diverse and species-rich supergroup of mostlyunicellular[3]eukaryotes.[4]Except for theChlorarachniophytesand three species in the genusPaulinellain the phylumCercozoa,they are all non-photosynthetic, but many foraminifera and radiolaria have a symbiotic relationship with unicellular algae.[5]A multicellular form,Guttulinopsis vulgaris,a cellularslime mold,has been described.[6]This group was used byCavalier-Smithin 2002, although the term "Rhizaria" had been long used for clades within the currently recognized taxon.

Being described mainly fromrDNAsequences, they vary considerably in form, having no clear morphological distinctive characters (synapomorphies), but for the most part they areamoeboidswithfilose,reticulose,ormicrotubule-supportedpseudopods.In the absence of an apomorphy, the group is ill-defined, and its composition has been very fluid. Some Rhizaria possess mineral exoskeletons (thecaeorloricas), which are in different clades within Rhizaria made out ofopal(SiO2),celestite(SrSO4), orcalcite(CaCO3).

Certain species can attain sizes of more than a centimeter with some species being able to form cylindrical colonies approximately 1 cm in diameter and greater than 1 m in length. They feed by capturing and engulfing prey with the extensions of their pseudopodia; forms that are symbiotic with unicellular algae contribute significantly to the total primary production of the ocean.[7]

Groups[edit]

Further information:wikispecies:Rhizaria

The three main groups of Rhizaria are:[8]

A few other groups may be included in the Cercozoa, but some trees appear closer to the Foraminifera. These are thePhytomyxeaandAscetosporea,parasites of plants and animals, respectively, and the peculiar amoebaGromia.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 byCavalier-Smithin 2002,[9]who also included thecentrohelidsandApusozoa.

A noteworthy order that belongs toAscetosporeais theMikrocytida.[10]These are parasites ofoysters.This includes the causative agent of Denman Island Disease,Mikrocytos mackinia small (2−3 μm diameter) amitochondriate protistan.[11]

History[edit]

Similarities between various Rhizaria organisms have been noticed since the 19th century. In his 1861 classification of theRhizopoda(amoebae), the zoologistWilliam B. Carpenterproposed the orderReticularia,which consisted ofForaminiferaandGromiidaon the basis of their very similar thin, reticulose pseudopodia with granules circulating inside.[12]However, the idea that these organisms and others such asRadiolariawere all related to one another emerged rather recently, with the help of molecular phylogenetics and advanced microscopy techniques in the late 20th century.[13]

Evolutionary relationships[edit]

See also:Eukaryote § Phylogeny

Rhizaria are part of theSAR supergroup(Stramenopiles, Alveolates, Rhizaria), a grouping that had been presaged in 1993 through a study of mitochondrial morphologies.[14]SAR is currently placed in theDiaphoretickesalong withArchaeplastida,Cryptista,Haptista,and several minor clades.

Historically, many rhizarians were consideredanimalsbecause of their motility andheterotrophy.However, when a simple animal-plant dichotomy was superseded by a recognition of additional kingdoms, taxonomists generally placed amoebae in the kingdomProtista.When scientists began examining the evolutionary relationships among eukaryotes in the 1970s, it became clear that the kingdomProtistawasparaphyletic.Rhizaria appear to share a common ancestor withStramenopilesandAlveolatesforming part of the SAR super assemblage.[15]Rhizaria has been supported by molecular phylogenetic studies as a monophyletic group.[16]Biosynthesis of24-isopropyl cholestaneprecursors in various rhizaria[17]suggests a relevant ecological role already during theEdiacaran.

Phylogeny[edit]

Rhizaria is amonophyletic groupcomposed of two sister phyla:CercozoaandRetaria.Subsequently, Cercozoa and Retaria are alsomonophyletic.[18][19]The following cladogram depicts the evolutionary relationships between all rhizarianclasses,and is made after the works ofCavalier-Smithet al.(2018),[1]and Irwinet al.(2019).[20]

SAR Supergroup

Sexual cycle[edit]

Complete sexual life cycles have been demonstrated for two lineages (ForaminiferaandGromia) and direct evidence forkaryogamyormeiosishas been observed in five lineages (Euglyphida,Thecofilosea,Chlorarachniophyta,PlasmodiophoridaandPhaeodarea).[21]In particular, theForamaniferaare marineamoebaethat are defined by a dynamic network ofpseudopodia,and the production of intricate shells.[21]These amoeba have complex sexual life cycles with meiosis andgameteproduction occurring at separate stages.[21]

References[edit]

  1. ^abCavalier-Smith, Thomas;Chao, Ema E.; Lewis, Rhodri (April 2018)."Multigene phylogeny and cell evolution of chromist infrakingdom Rhizaria: contrasting cell organisation of sister phyla Cercozoa and Retaria".Protoplasma.255(5): 1517–1574.doi:10.1007/s00709-018-1241-1.PMC6133090.PMID29666938.
  2. ^Sina M. Adl; David Bass; Christopher E. Lane; et al. (1 January 2019)."Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes".Journal of Eukaryotic Microbiology.66(1): 4–119.doi:10.1111/JEU.12691.ISSN1066-5234.PMC6492006.PMID30257078.WikidataQ57086550.
  3. ^Taylor, Christopher (2004)."Rhizaria".Archived fromthe originalon 2009-04-20.
  4. ^Nikolaev, Sergey I.; Berney, Cédric; Fahrni, José F.; et al. (May 2004)."The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes".PNAS.101(21): 8066–71.doi:10.1073/pnas.0308602101.PMC419558.PMID15148395.
  5. ^Gast, Rebecca J.; Caron, David A. (2001-10-01). "Photosymbiotic associations in planktonic foraminifera and radiolaria".Hydrobiologia.461(1): 1–7.doi:10.1023/A:1012710909023.S2CID1387879.
  6. ^Brown, Matthew W.; Kolisko, Martin; Silberman, Jeffrey D.; Roger, Andrew J. (June 2012)."Aggregative Multicellularity Evolved Independently in the Eukaryotic Supergroup Rhizaria".Current Biology.22(12): 1123–7.Bibcode:2012CBio...22.1123B.doi:10.1016/j.cub.2012.04.021.PMID22608512.
  7. ^Caron DA (April 2016). "Ocean science: The rise of Rhizaria".Nature.532(7600): 444–5.Bibcode:2016Natur.532..444C.doi:10.1038/nature17892.PMID27096370.
  8. ^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.Bibcode:2007MolPE..44..255M.doi:10.1016/j.ympev.2006.11.001.PMID17174576.
  9. ^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.doi:10.1099/00207713-52-2-297.PMID11931142.
  10. ^Hartikainen, H.; Stentiford, G.D.; Bateman, K.S.; Berney, C.; Feist, S.W.; Longshaw, M.; Okamura, B.; Stone, D.; Ward, G.; Wood, C.; Bass, D. (2014)."Mikrocytids are a broadly distributed and divergent radiation of parasites in aquatic invertebrates"(PDF).Curr Biol.24(7): 807–12.Bibcode:2014CBio...24..807H.doi:10.1016/j.cub.2014.02.033.PMID24656829.S2CID17180719.
  11. ^Hine, P.M.; Bower, S.M.; Meyer, G.R.; Cochennec-Laureau, N.; Berthe, F.C.J. (2001)."Ultrastructure ofMikrocytos mackini,the cause of Denman Island disease in oysters Crassostrea spp. and Ostrea spp. in British Columbia, Canada ".Diseases of Aquatic Organisms.45(3): 215–227.doi:10.3354/dao045215.PMID11558731.
  12. ^Carpenter, William Benjamin (1861)."XLVII.-On the systematic arrangement of the Rhizopoda".Natural History Review (Dublin and London).1(4): 478.
  13. ^Burki F, Keeling PJ (February 2014)."Rhizaria".Current Biology.24(3): R103–7.Bibcode:2014CBio...24.R103B.doi:10.1016/j.cub.2013.12.025.PMID24502779.
  14. ^Seravin LN (1993). "[The basic types and forms of the fine structure of mitochondrial cristae: the degree of their evolutionary stability (capacity for morphological transformations)]".Tsitologiia(in Russian).35(4): 3–34.PMID8328023.
  15. ^Burki, F.; Shalchian-Tabrizi, K.; Minge, M.; Skjaeveland, A.; Nikolaev, S.I.; Jakobsen, K.S.; Pawlowski, J. (2007). Butler, Geraldine (ed.)."Phylogenomics Reshuffles the Eukaryotic Supergroups".PLoS ONE.2(8): e790–.Bibcode:2007PLoSO...2..790B.doi:10.1371/journal.pone.0000790.PMC1949142.PMID17726520.
  16. ^Burki, Fabien; Shalchian-Tabrizi, Kamran; Pawlowski, Jan (August 23, 2008)."Phylogenomics reveals a new 'megagroup' including most photosynthetic eukaryotes".Biology Letters.4(4): 366–9.doi:10.1098/rsbl.2008.0224.PMC2610160.PMID18522922.
  17. ^Hallmann, Christian; Stuhr, Marleen; Kucera, Michal; et al. (2019-03-04). "Putative sponge biomarkers in unicellular Rhizaria question an early rise of animals".Nature Ecology & Evolution.3(4): 577–581.Bibcode:2019NatEE...3..577N.doi:10.1038/s41559-019-0806-5.PMID30833757.S2CID71148672.
  18. ^Bass, D.; Chao, E.E.; Nikolaev, S.; et al. (February 2009). "Phylogeny of Novel Naked Filose and Reticulose Cercozoa: Granofilosea cl. n. and Proteomyxidea Revised".Protist.160(1): 75–109.doi:10.1016/j.protis.2008.07.002.PMID18952499.
  19. ^>Howe, Alexis T.; Bass, David; Scoble, Josephine M.; et al. (2011). "Novel Cultured Protists Identify Deep-branching Environmental DNA Clades of Cercozoa: New Genera Tremula, Micrometopion, Minimassisteria, Nudifila, Peregrinia".Protist.162(2): 332–372.doi:10.1016/j.protis.2010.10.002.PMID21295519.
  20. ^Irwin, Nicholas A. T.; Tikhonenkov, Denis V.; Hehenberger, Elisabeth; et al. (2019-01-01). "Phylogenomics supports the monophyly of the Cercozoa".Molecular Phylogenetics and Evolution.130:416–423.Bibcode:2019MolPE.130..416I.doi:10.1016/j.ympev.2018.09.004.PMID30318266.S2CID52982396.
  21. ^abcLahr DJ, Parfrey LW, Mitchell EA, Katz LA, Lara E (July 2011)."The chastity of amoebae: re-evaluating evidence for sex in amoeboid organisms".Proc Biol Sci.278(1715): 2081–90.doi:10.1098/rspb.2011.0289.PMC3107637.PMID21429931.

External links[edit]

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