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	The '''Rhizaria''' are a species-rich supergroup of mostly ]<ref>{{cite web \| url = http://www.palaeos.com/Eukarya/Units/Rhizaria/Rhizaria.html \| year = 2004 \| author = Christopher Taylor \| title = Rhizaria \| url-status = dead \| archive-url = https://web.archive.org/web/20090420034036/http://www.palaeos.com/Eukarya/Units/Rhizaria/Rhizaria.html \| archive-date = 2009-04-20 }}</ref> ]s.<ref name="pmid15148395">{{cite journal \|vauthors=Nikolaev SI, Berney C, Fahrni JF, etal \|title=The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes \|journal=Proc. Natl. Acad. Sci. U.S.A. \|volume=101 \|issue=21 \|pages=8066–71 \|date=May 2004 \|pmid=15148395 \|pmc=419558 \|doi=10.1073/pnas.0308602101 \|doi-access=free }}</ref> Except for the ] and three species in the genus ] in the phylum ], they are all non-photosynthethic, but many foraminifera and radiolaria have a symbiotic relationship with unicellular algae.<ref>{{Cite journal\|last1=Gast\|first1=Rebecca J.\|last2=Caron\|first2=David A.\|date=2001-10-01\|title=Photosymbiotic associations in planktonic foraminifera and radiolaria\|journal=Hydrobiologia\|language=en\|volume=461\|issue=1\|pages=1–7\|doi=10.1023/A:1012710909023\|s2cid=1387879\|issn=1573-5117}}</ref> A multicellular form, ''Guttulinopsis vulgaris'', a cellular ], has also been described.<ref>{{cite journal \| year = 2012 \| author = Brown\| title = Aggregative Multicellularity Evolved Independently in the Eukaryotic Supergroup Rhizaria \|display-authors=etal \| doi=10.1016/j.cub.2012.04.021 \| volume=22 \| issue = 12 \| journal=Current Biology \| pages=1123–1127 \| pmid=22608512\| doi-access=free }}</ref>		The '''Rhizaria''' are an ill-defined but species-rich supergroup of mostly ]<ref>{{cite web \| url = http://www.palaeos.com/Eukarya/Units/Rhizaria/Rhizaria.html \| year = 2004 \| author = Christopher Taylor \| title = Rhizaria \| url-status = dead \| archive-url = https://web.archive.org/web/20090420034036/http://www.palaeos.com/Eukarya/Units/Rhizaria/Rhizaria.html \| archive-date = 2009-04-20 }}</ref> ]s.<ref name="pmid15148395">{{cite journal \|vauthors=Nikolaev SI, Berney C, Fahrni JF, etal \|title=The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes \|journal=Proc. Natl. Acad. Sci. U.S.A. \|volume=101 \|issue=21 \|pages=8066–71 \|date=May 2004 \|pmid=15148395 \|pmc=419558 \|doi=10.1073/pnas.0308602101 \|doi-access=free }}</ref> Except for the ] and three species in the genus ] in the phylum ], they are all non-photosynthethic, but many foraminifera and radiolaria have a symbiotic relationship with unicellular algae.<ref>{{Cite journal\|last1=Gast\|first1=Rebecca J.\|last2=Caron\|first2=David A.\|date=2001-10-01\|title=Photosymbiotic associations in planktonic foraminifera and radiolaria\|journal=Hydrobiologia\|language=en\|volume=461\|issue=1\|pages=1–7\|doi=10.1023/A:1012710909023\|s2cid=1387879\|issn=1573-5117}}</ref> A multicellular form, ''Guttulinopsis vulgaris'', a cellular ], has also been described.<ref>{{cite journal \| year = 2012 \| author = Brown\| title = Aggregative Multicellularity Evolved Independently in the Eukaryotic Supergroup Rhizaria \|display-authors=etal \| doi=10.1016/j.cub.2012.04.021 \| volume=22 \| issue = 12 \| journal=Current Biology \| pages=1123–1127 \| pmid=22608512\| doi-access=free }}</ref>
	This ~~supergroup~~ was ~~proposed~~ by ] in 2002, although the term "Rhizaria" had been long used for ~~many~~ clades within the currently recognized taxon. Being described mainly from ] sequences, they vary considerably in form, having no clear morphological distinctive characters (]), but for the most part they are ]s with filose, reticulose, or microtubule-supported ]s. In the absence of an apomorphy, the group is ill-defined, and its composition has been very fluid. ~~Many~~ Rhizaria posess mineral exoskeleton (thecae or loricas), which is in different clades within Rhizaria made out of opal ({{chem2\|SiO2}}), celestite ({{chem2\|SrSO4}}), or calcite ({{chem2\|CaCO3}}). It 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.<ref>Caron, D. (2016). The rise of Rhizaria. Nature (London), 532(7600), 444–445. https://doi.org/10.1038/nature17892</ref>		This group was used by ] in 2002, although the term "Rhizaria" had been long used for clades within the currently recognized taxon. Being described mainly from ] sequences, they vary considerably in form, having no clear morphological distinctive characters (]), but for the most part they are ]s with filose, reticulose, or microtubule-supported ]s. In the absence of an apomorphy, the group is ill-defined, and its composition has been very fluid. Some Rhizaria posess mineral exoskeleton (thecae or loricas), which is in different clades within Rhizaria made out of opal ({{chem2\|SiO2}}), celestite ({{chem2\|SrSO4}}), or calcite ({{chem2\|CaCO3}}). It 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.<ref>Caron, D. (2016). The rise of Rhizaria. Nature (London), 532(7600), 444–445. https://doi.org/10.1038/nature17892</ref>

	==Groups==		==Groups==
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	==Evolutionary relationships==		==Evolutionary relationships==
	{{See also\|Eukaryote#Phylogeny}}		{{See also\|Eukaryote#Phylogeny}}
	Rhizaria are part of the ] (Stramenopiles, Alveolates, Rhizaria), ~~which~~ is ~~turn~~ ~~belongs~~ to a ~~upper-level~~ ~~taxon~~ ] (~~bikont~~) ] along with ], ], ], and several minor clades.		Rhizaria are part of the ] (Stramenopiles, Alveolates, Rhizaria), a grouping that had been presaged in 1993 through a study of mitochondrial morphologies <ref>Seravin LN. Osnovnye tipy i formy tonkogo stroeniia krist mitokhondriĭ: stepen' ikh évoliutsionnoĭ stabil'nosti (sposobnost' k morfologicheskim transformatsiiam) . Tsitologiia. 1993;35(4):3-34. Russian. PMID: 8328023.</ref>. SAR is currently placed in the ] along with ], ], ], and several minor clades.

	Historically, many rhizarians were considered ]s because of their motility and ]. However, when a simple animal-plant dichotomy was superseded by a recognition of additional kingdoms, taxonomists generally placed ~~Rhizarians~~ in the kingdom ]. When scientists began examining the evolutionary relationships among eukaryotes ~~using~~ ~~molecular~~ ~~data~~, it became clear that the kingdom ] was ]. Rhizaria appear to share a common ancestor with ] and ] forming part of the SAR (Stramenopiles+Alveolates+Rhizaria) super assemblage.<ref>{{cite journal \| title = Phylogenomics Reshuffles the Eukaryotic Supergroups\| journal = ]\| year = 2007 \| volume = 2 \| pages = e790– \| issue = 8\| doi = 10.1371/journal.pone.0000790 \| pmid = 17726520 \| last1 = Burki \| first1 = F\| last2 = Shalchian-Tabrizi \| first2 = K \| last3 = Minge \| first3 = M \| last4 = Skjaeveland \| first4 = A \| last5 = Nikolaev \| first5 = SI \| last6 = Jakobsen \| first6 = KS \| last7 = Pawlowski \| first7 = J \| pmc = 1949142 \| editor1-last = Butler \| editor1-first = Geraldine		Historically, many rhizarians were considered ]s because of their motility and ]. However, when a simple animal-plant dichotomy was superseded by a recognition of additional kingdoms, taxonomists generally placed amoebae in the kingdom ]. When scientists began examining the evolutionary relationships among eukaryotes in the 1970's, it became clear that the kingdom ] was ]. Rhizaria appear to share a common ancestor with ] and ] forming part of the SAR (Stramenopiles+Alveolates+Rhizaria) super assemblage.<ref>{{cite journal \| title = Phylogenomics Reshuffles the Eukaryotic Supergroups\| journal = ]\| year = 2007 \| volume = 2 \| pages = e790– \| issue = 8\| doi = 10.1371/journal.pone.0000790 \| pmid = 17726520 \| last1 = Burki \| first1 = F\| last2 = Shalchian-Tabrizi \| first2 = K \| last3 = Minge \| first3 = M \| last4 = Skjaeveland \| first4 = A \| last5 = Nikolaev \| first5 = SI \| last6 = Jakobsen \| first6 = KS \| last7 = Pawlowski \| first7 = J \| pmc = 1949142 \| editor1-last = Butler \| editor1-first = Geraldine
	\| bibcode = 2007PLoSO...2..790B\| doi-access = free}}</ref> Rhizaria has been supported by molecular phylogenetic studies as a monophyletic group.<ref name=Burki2008>{{cite journal\|last1=Burki \|first1=Fabien \|last2=Shalchian-Tabrizi \|first2=Kamran \|last3=Pawlowski \|first3=Jan \|title=Phylogenomics reveals a new 'megagroup' including most photosynthetic eukaryotes \|journal=Biology Letters \|date=August 23, 2008 \|doi=10.1098/rsbl.2008.0224 \|pmid=18522922 \|volume=4 \|issue=4 \|pmc=2610160 \|pages=366–9}}</ref> Biosynthesis of ] precursors in various rhizaria<ref>{{Cite journal\|last1=Hallmann\|first1=Christian\|last2=Stuhr\|first2=Marleen\|last3=Kucera\|first3=Michal\|last4=Zonneveld\|first4=Karin\|last5=Bobrovskiy\|first5=Ilya\|last6=Bowser\|first6=Samuel S.\|last7=Pawlowski\|first7=Jan\|last8=Deckker\|first8=Patrick De\|last9=Nowack\|first9=Eva C. M.\|date=2019-03-04\|title=Putative sponge biomarkers in unicellular Rhizaria question an early rise of animals\|journal=Nature Ecology & Evolution\|volume=3\|issue=4\|language=en\|pages=577–581\|doi=10.1038/s41559-019-0806-5\|pmid=30833757\|s2cid=71148672\|issn=2397-334X}}</ref> suggests a relevant ecological role already during the ].		\| bibcode = 2007PLoSO...2..790B\| doi-access = free}}</ref> Rhizaria has been supported by molecular phylogenetic studies as a monophyletic group.<ref name=Burki2008>{{cite journal\|last1=Burki \|first1=Fabien \|last2=Shalchian-Tabrizi \|first2=Kamran \|last3=Pawlowski \|first3=Jan \|title=Phylogenomics reveals a new 'megagroup' including most photosynthetic eukaryotes \|journal=Biology Letters \|date=August 23, 2008 \|doi=10.1098/rsbl.2008.0224 \|pmid=18522922 \|volume=4 \|issue=4 \|pmc=2610160 \|pages=366–9}}</ref> Biosynthesis of ] precursors in various rhizaria<ref>{{Cite journal\|last1=Hallmann\|first1=Christian\|last2=Stuhr\|first2=Marleen\|last3=Kucera\|first3=Michal\|last4=Zonneveld\|first4=Karin\|last5=Bobrovskiy\|first5=Ilya\|last6=Bowser\|first6=Samuel S.\|last7=Pawlowski\|first7=Jan\|last8=Deckker\|first8=Patrick De\|last9=Nowack\|first9=Eva C. M.\|date=2019-03-04\|title=Putative sponge biomarkers in unicellular Rhizaria question an early rise of animals\|journal=Nature Ecology & Evolution\|volume=3\|issue=4\|language=en\|pages=577–581\|doi=10.1038/s41559-019-0806-5\|pmid=30833757\|s2cid=71148672\|issn=2397-334X}}</ref> suggests a relevant ecological role already during the ].

Revision as of 00:37, 22 December 2021

Infrakingdom of protists

Rhizaria Temporal range: Neoproterozoic - Recent Pha. Proterozoic Archean Had.

Ammonia tepida (Foraminifera)
Scientific classification
Domain:	Eukaryota
Clade:	Diaphoretickes
Clade:	TSAR
Clade:	SAR
Clade:	Rhizaria Cavalier-Smith, 2002
Phyla
Cercozoa Retaria Foraminifera Radiolaria

The Rhizaria are an ill-defined but species-rich supergroup of mostly unicellular eukaryotes. Except for the Chlorarachniophytes and three species in the genus Paulinella in the phylum Cercozoa, they are all non-photosynthethic, but many foraminifera and radiolaria have a symbiotic relationship with unicellular algae. A multicellular form, Guttulinopsis vulgaris, a cellular slime mold, has also been described. This group was used by Cavalier-Smith in 2002, although the term "Rhizaria" had been long used for clades within the currently recognized taxon. Being described mainly from rDNA sequences, they vary considerably in form, having no clear morphological distinctive characters (synapomorphies), but for the most part they are amoeboids with filose, reticulose, or microtubule-supported pseudopods. In the absence of an apomorphy, the group is ill-defined, and its composition has been very fluid. Some Rhizaria posess mineral exoskeleton (thecae or loricas), which is in different clades within Rhizaria made out of opal (SiO₂), celestite (SrSO₄), or calcite (CaCO₃). It 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.

Groups

Further information: wikispecies:Rhizaria

The three main groups of Rhizaria are:

Cercozoa – various amoebae and flagellates, usually with filose pseudopods and common in soil
Foraminifera – amoeboids with reticulose pseudopods, common as marine benthos
Radiolaria – amoeboids with axopods, common as marine plankton

A few other groups may be included in the Cercozoa, but 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, who also included the centrohelids and Apusozoa.

A noteworthy order that belongs to Ascetosporea is the Mikrocytida. These are parasites of oysters. This includes the causative agent of Denman Island Disease, Mikrocytos mackini a small (2−3 μm diameter) amitochondriate protistan.

Revision as of 00:37, 22 December 2021

Groups

Evolutionary relationships

Phylogeny

References

External links