SAR supergroup

{{Short description|Eukaryotic supergroup that comprises stramenopiles, alveolates and rhizarians}} {{Hatnote group|{{Redirect-distinguish|TSAR|Tsar|TSAR Publications}} {{Otheruses|Tsar (disambiguation)}}}} {{Automatic taxobox | name = Sar | fossil_range = {{long fossil range|736|0|earliest=1577|ref=<ref name="Parfrey2011"/>}} | image = Harosa.png | image_caption = | display_parents = 2 | taxon = Sar | authority = Burki et al., 2008 emend. Adl et al., 2012<ref>{{Cite journal |last1=Adl |first1=Sina M. |last2=Bass |first2=David |last3=Lane |first3=Christopher E. |last4=Lukeš |first4=Julius |last5=Schoch |first5=Conrad L. |last6=Smirnov |first6=Alexey |last7=Agatha |first7=Sabine |last8=Berney |first8=Cedric |last9=Brown |first9=Matthew W. |last10=Burki |first10=Fabien |last11=Cárdenas |first11=Paco |last12=Čepička |first12=Ivan |last13=Chistyakova |first13=Lyudmila |last14=del Campo |first14=Javier |last15=Dunthorn |first15=Micah |date=2019 |title=Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes |journal=Journal of Eukaryotic Microbiology |language=en |volume=66 |issue=1 |pages=4–119 |doi=10.1111/jeu.12691 |issn=1550-7408 |pmc=6492006 |pmid=30257078 |doi-access=free}}</ref> | subdivision_ranks = Subgroups | subdivision = * Halvaria ** Stramenopiles (heterokonts) ** Alveolata * Rhizaria | synonyms = * Harosa Cavalier-Smith, 2010 * SAR Burki et al., 2008 * RAS Baldauf, 2008 }}

'''SAR'''{{refn|As a formal taxon, Sar has only its first letter capitalized, while the earlier abbreviation, SAR, retains all uppercase letters. Both names denote the same group of organisms.<ref name="Adl-2012">{{Cite journal |last1=Adl |first1=Sina M. |last2=Simpson |first2=Alastair G. B. |last3=Lane |first3=Christopher E. |last4=Lukeš |first4=Julius |last5=Bass |first5=David |last6=Bowser |first6=Samuel S. |last7=Brown |first7=Matthew W. |last8=Burki |first8=Fabien |last9=Dunthorn |first9=Micah |last10=Hampl |first10=Vladimir |last11=Heiss |first11=Aaron |last12=Hoppenrath |first12=Mona |last13=Lara |first13=Enrique |last14=le Gall |first14=Line |last15=Lynn |first15=Denis H. |date=September 2012 |title=The Revised Classification of Eukaryotes |journal=Journal of Eukaryotic Microbiology |language=en |volume=59 |issue=5 |pages=429–514 |doi=10.1111/j.1550-7408.2012.00644.x |issn=1066-5234 |pmc=3483872 |pmid=23020233}}</ref>|group=nb}} is a highly diverse clade of eukaryotes, often considered a supergroup,<ref name="eToL"/> that includes stramenopiles (heterokonts), alveolates, and rhizarians.<ref name="pmid17726520"/><ref name="pmid19237557"/><ref name="pmid18799712"/> It is a node-based taxon (under the '''Sar''' name), including all descendants of the three groups' last common ancestor,<ref name="adl2012"/> and comprises most of the now-rejected Chromalveolata.<ref name="eToL"/> Their sister group might be telonemids, with which they would make up the TSAR clade,<ref name="Telonemia"/> but this grouping has been challenged.<ref name="CAM clade" /><ref name="Torruella 2024" /> '''Harosa''' is used synonymously with TSAR by Cavalier-Smith in 2022.<ref>{{Cite journal |last=Cavalier-Smith |first=Thomas |date=2022-05-01 |title=Ciliary transition zone evolution and the root of the eukaryote tree: implications for opisthokont origin and classification of kingdoms Protozoa, Plantae, and Fungi |journal=Protoplasma |language=en |volume=259 |issue=3 |pages=487–593 |doi=10.1007/s00709-021-01665-7 |issn=1615-6102 |pmc=9010356 |pmid=34940909 |bibcode=2022Prpls.259..487C }}</ref>

== Etymology ==

The name SAR is an acronym derived from the first letters of its three constituent clades; it has been alternatively spelled RAS.<ref name="J1"/> The term Harosa (at the subkingdom level) has also been used, with Stramenopiles replaced by its synonym Heterokonta in this variant of the acronym.<ref name="pmid20031978"/>

== History of discovery ==

Before the discovery of the SAR supergroup, stramenopiles and alveolates were classified in the supergroup Chromalveolata alongside haptophytes and cryptomonads, being believed to have acquired plastids through secondary endosymbiosis of red algae through a common ancestor.<ref name="eToL"/> Meanwhile, Rhizaria was traditionally considered to be a separate supergroup. More recent phylogenetic studies confirmed that stramenopiles and alveolates diverged with rhizarians as part of the SAR lineage.<ref name="Ancestor"/> This clade has been found by later phylogenomic studies to be robustly characterized compared to other supergroups.<ref name="Telonemia"/>

This group excludes haptophytes and cryptomonads, hypothesized to have acquired plastids in separate endosymbiosis events,<ref name="Strassert 2021"/> leading Okamoto ''et al.'' (2009) to propose the clade Hacrobia to accommodate them.<ref name="burki2014"/>

== Diversity ==

The SAR supergroup encompasses a variety of morphologies and ecological niches, from microscopic zoo- and phytoplankton to massive kelp forests. The group includes both photosynthetic and non-photosynthetic forms. Photosynthesis arose independently across various stramenopile and alveolate lineages through secondary or higher-order endosymbiosis events, acquiring plastids of red algal origin,<ref name="McFadden 2001"/><ref name="Strassert 2021"/> while chlorarachniophyte rhizarians captured plastids from green algae, retaining vestigial nucleomorphs.<ref name="pmid19174147"/>

It has been estimated that SAR encompasses up to half of all eukaryotic diversity.<ref name="eToL"/>

Owing to the clade's discovery through phylogenomics, there are no known synapomorphies uniting its various members.<ref name="pmid17726520"/> This was already the case for its subclade Rhizaria, established earlier through similar means. On the other hand, Stramenopiles is well-defined morphologically, characterized by an anterior flagellum with tripartite bristles (mastigonemes), while Alveolata is united by the presence of cortical alveoli.<ref name="Microbial Diversity"/>

Nonetheless, studies of telonemids have revealed characteristics such as tripartite hair and peripheral vacuoles, potentially homologous to similar structures in stramenopiles and alveolates. This brings into light the possibility of these structures being ancestrally shared by the clade, with cortical alveoli originating from peripheral vacuoles under this hypothesis.<ref name="Telonemia"/>

=== Internal phylogeny ===

A 2021 analysis places Alveolata and Stramenopiles in Halvaria, as sister to Rhizaria.<ref name="Strassert 2021"/>

{{clade| style=font-size:100%;line-height:80% |1={{clade |label1='''SAR''' / |sublabel1='''Harosa''' |1={{clade |1=Rhizaria 50px |label2=Halvaria |2={{clade |1=Alveolata 90px |2=Stramenopiles 50px }} }} }} }}

== See also == * Amoebozoa * Archaeplastida * Excavata * Opisthokonta

== Notes == {{reflist|group=nb}}

== References == {{reflist|30em|refs= <ref name="Parfrey2011">{{cite Q|Q24614721|name-list-style=vanc}}</ref> <ref name="pmid19174147">{{cite journal | vauthors = Archibald JM | title = The puzzle of plastid evolution | journal = Current Biology | volume = 19 | issue = 2 | pages = R81-8 | date = January 2009 | pmid = 19174147 | doi = 10.1016/j.cub.2008.11.067 | s2cid = 51989 | doi-access = free | bibcode = 2009CBio...19..R81A }}</ref> <ref name="pmid17726520">{{cite journal | vauthors = Burki F, Shalchian-Tabrizi K, Minge M, Skjaeveland A, Nikolaev SI, Jakobsen KS, Pawlowski J | title = Phylogenomics reshuffles the eukaryotic supergroups | journal = PLOS ONE | volume = 2 | issue = 8 | article-number = e790 | date = August 2007 | pmid = 17726520 | pmc = 1949142 | doi = 10.1371/journal.pone.0000790 | veditors = Butler G | bibcode = 2007PLoSO...2..790B | doi-access = free }}</ref> <ref name="pmid19237557">{{cite journal | vauthors = Hampl V, Hug L, Leigh JW, Dacks JB, Lang BF, Simpson AG, Roger AJ | title = Phylogenomic analyses support the monophyly of Excavata and resolve relationships among eukaryotic "supergroups" | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 106 | issue = 10 | pages = 3859–64 | date = March 2009 | pmid = 19237557 | pmc = 2656170 | doi = 10.1073/pnas.0807880106 | bibcode = 2009PNAS..106.3859H | doi-access = free }}</ref> <ref name="pmid18799712">{{cite journal | vauthors = Frommolt R, Werner S, Paulsen H, Goss R, Wilhelm C, Zauner S, Maier UG, Grossman AR, Bhattacharya D, Lohr M | display-authors = 6 | title = Ancient recruitment by chromists of green algal genes encoding enzymes for carotenoid biosynthesis | journal = Molecular Biology and Evolution | volume = 25 | issue = 12 | pages = 2653–67 | date = December 2008 | pmid = 18799712 | doi = 10.1093/molbev/msn206 | doi-access = free }}</ref> <ref name="J1">{{cite journal| vauthors = Baldauf SL |year=2008 |title=An overview of the phylogeny and diversity of eukaryotes |journal=Journal of Systematics and Evolution |volume=46 |issue=3 |pages=263–273 |doi=10.3724/SP.J.1002.2008.08060 | url = https://pdfs.semanticscholar.org/c325/1ef9a0d7b00bc5e011df5dbf37629f42c4f5.pdf | archive-url = https://web.archive.org/web/20190820153714/https://pdfs.semanticscholar.org/c325/1ef9a0d7b00bc5e011df5dbf37629f42c4f5.pdf | archive-date = 2019-08-20 |doi-broken-date=12 July 2025 |s2cid=512766 }}</ref> <ref name="pmid20031978">{{cite journal | vauthors = Cavalier-Smith T | title = Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree | journal = Biology Letters | volume = 6 | issue = 3 | pages = 342–5 | date = June 2010 | pmid = 20031978 | pmc = 2880060 | doi = 10.1098/rsbl.2009.0948 | bibcode = 2010BiLet...6..342C }}</ref> <ref name="adl2012">{{cite journal | vauthors = Adl SM, Simpson AG, Lane CE, Lukeš J, Bass D, Bowser SS, Brown MW, Burki F, Dunthorn M, Hampl V, Heiss A, Hoppenrath M, Lara E, Le Gall L, Lynn DH, McManus H, Mitchell EA, Mozley-Stanridge SE, Parfrey LW, Pawlowski J, Rueckert S, Shadwick L, Shadwick L, Schoch CL, Smirnov A, Spiegel FW | display-authors = 6 | title = The revised classification of eukaryotes | journal = The Journal of Eukaryotic Microbiology | volume = 59 | issue = 5 | pages = 429–93 | date = September 2012 | pmid = 23020233 | pmc = 3483872 | doi = 10.1111/j.1550-7408.2012.00644.x | name-list-style = amp }}</ref> <ref name="Telonemia">{{cite journal | vauthors = Strassert JF, Jamy M, Mylnikov AP, Tikhonenkov DV, Burki F | title = New Phylogenomic Analysis of the Enigmatic Phylum Telonemia Further Resolves the Eukaryote Tree of Life | journal = Molecular Biology and Evolution | volume = 36 | issue = 4 | pages = 757–765 | date = April 2019 | pmid = 30668767 | pmc = 6844682 | doi = 10.1093/molbev/msz012 | veditors = Shapiro B }}</ref> <ref name="Ancestor">{{cite book |title=Ancestor's Tale |isbn=978-0-544-85993-7 |pages=573–577| vauthors = Dawkins R, Wong Y |year=2016 |publisher=Houghton Mifflin Harcourt }}</ref> <ref name="burki2014">{{cite journal | vauthors = Burki F | title = The eukaryotic tree of life from a global phylogenomic perspective | journal = Cold Spring Harbor Perspectives in Biology | volume = 6 | issue = 5 | article-number = a016147 | date = May 2014 | pmid = 24789819 | pmc = 3996474 | doi = 10.1101/cshperspect.a016147 }}</ref> <ref name="Strassert 2021">{{cite journal | author1= Strassert JF | author2 = Irisarri I | author3 = Williams TA | author4 = Burki F | title = A molecular timescale for eukaryote evolution with implications for the origin of red algal-derived plastids | journal = Nature Communications | volume = 12 | issue = 1 | page = 1879 | date = March 2021 | pmid = 33767194 | pmc = 7994803 | doi = 10.1038/s41467-021-22044-z | bibcode = 2021NatCo..12.1879S }}</ref> <ref name="McFadden 2001">{{cite journal |last=McFadden |first=G. I. |title=Primary and secondary endosymbiosis and the origin of plastids |journal=Journal of Phycology |year=2001 |volume=37 |issue=6 |pages=951–959 |doi=10.1046/j.1529-8817.2001.01126.x |bibcode=2001JPcgy..37..951M |s2cid=51945442 }}</ref> <ref name="eToL">{{cite journal|title=The New Tree of Eukaryotes|last1=Burki|first1=Fabien|last2=Roger|first2=Andrew J.|last3=Brown|first3=Matthew W.|last4=Simpson|first4=Alastair G.B.|date=January 2020|journal= Trends in Ecology & Evolution|volume=35|issue=1|pages=43–55|doi=10.1016/j.tree.2019.08.008|doi-access=free|pmid=31606140 |bibcode=2020TEcoE..35...43B }}</ref> <ref name="Microbial Diversity">{{cite journal|title=Microbial Diversity in the Eukaryotic SAR Clade: Illuminating the Darkness Between Morphology and Molecular DataDarkness Between Morphology and Molecular Data|last1=Grattepanche|first1=Jean David |display-authors=etal |journal=BioEssays|date=March 2018 |volume=40 |issue=4 |article-number=e1700198 |doi=10.1002/bies.201700198 |doi-access=free |pmid=29512175 }}</ref> <ref name="CAM clade">{{cite journal|last1=Yazaki|first1=Euki |last2=Yabuki|first2=Akinori |last3=Imaizumi|first3=Ayaka |last4=Kume|first4=Keitaro |last5=Hashimoto|first5=Tetsuo |last6=Inagaki|first6=Yuji|date=2022|title=The closest lineage of Archaeplastida is revealed by phylogenomics analyses that include Microheliella maris|journal=Open Biol.|volume=12|issue=4 |article-number=210376|doi=10.1098/rsob.210376|doi-access=free|pmid=35414259 |pmc=9006020}}</ref> <ref name="Torruella 2024">{{cite journal |last1=Torruella |first1=Guifré |last2=Galindo |first2=Luis Javier |last3=Moreira |first3=David |last4=López-García |first4=Purificación |title=Phylogenomics of neglected flagellated protists supports a revised eukaryotic tree of life |journal=Current Biology |date=2025 |volume=35 |issue=1 |pages=198–207.e4 |biorxiv=10.1101/2024.05.15.594285 |doi=10.1016/j.cub.2024.10.075 |pmid=39642877 |bibcode=2025CBio...35..198T |hdl=10481/102343 |hdl-access=free }}</ref> }}

Category:Protist taxa Category:SAR supergroup