Halvaria

{{Short description|Clade of protists}} {{Automatic taxobox | image = {{Multiple image | perrow = 2/2/2 | total_width = 275 | image1 = Water mold Mizukabi colony.jpg | caption1 = | image2 = Bladder Wrack (Fucus vesiculosus) - geograph.org.uk - 224125.jpg | caption2 = | image3 = Parasite140015-fig2 Protoopalina pingi (Opalinidae) Microscopy.tif | caption3 = | image4 = Diatoms through the microscope.jpg | caption4 = | image5 = Stentory.jpg | caption5 = | image6 = Dinoflagellates.jpg | caption6 = | border = infobox }} | image_caption = Important halvarian groups. Clockwise from top-left: a water mold (Oomycetes), a brown alga (Phaeophyta), some diatoms (Bacillariophyta), some dinoflagellates (Miozoa), some ciliates (Ciliophora) and an opalinid (Bigyra). | taxon = Halvaria | authority = Cavalier-Smith, 2010 | subdivision_ranks = Subgroups | subdivision_ref = <ref name="8phyla"/> | subdivision = * Stramenopiles (Heterokonta) * Alveolata }}

'''Halvaria''' is a taxonomic grouping of protists that includes Alveolata and Stramenopiles (Heterokonta).<ref name="pmid20031978"/>

Analyses in 2007 and 2008 revealed that the Stramenopiles and the Alveolata are related, and form a reduced clade of what were seen to be a paraphyletic group, the chromalveolates. The two clades together with the Rhizaria (originally one of the six major eukaryote groups) form a clade dubbed the SAR supergroup.<ref name="PhylogenomicsReshuffles"/><ref name=Burki2008a/><ref name=KimGraham2008/>

A phylogenomic analysis from 2016 cast doubt on Halvaria, suggesting that Alveolata is the sister group to Rhizaria (making the ''R + A clade'') through new rhizarian sequence data, and that support for Halvaria might be an artifact of low taxon sampling as well as long branch attraction.<ref name="ReducingLongBranchAlveolataRhizaria"/>

However, later analyses from 2021 support Halvaria as a solid clade.<ref name="AMolecularTimescale"/>

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

== References == {{Reflist|refs=

<ref name="pmid20031978">{{cite journal | author = Cavalier-Smith, Thomas | title = Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree | journal = Biology Letters | volume = 6 | issue = 3 | pages = 342–345 | date = June 2010 | pmid = 20031978 | pmc = 2880060 | doi = 10.1098/rsbl.2009.0948 }}</ref>

<ref name="PhylogenomicsReshuffles">{{cite journal | author1 = Burki, F. | author2 = Shalchian-Tabrizi | author3 = K. Minge, M. | author4 = Skjaeveland, A. | author5 = Nikolaev, S.I. | author6 = Jakobsen, K.S. | author7 = Pawlowski, J. | display-authors=3 | 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 | doi-access = free }} {{open access}}</ref>

<ref name=Burki2008a>{{cite journal | author1 = Burki, F. | author2 = Shalchian-Tabrizi | author3 = Pawlowski, J. | title = Phylogenomics reveals a new 'megagroup' including most photosynthetic eukaryotes | journal = Biology Letters | volume = 4 | issue = 4 | pages = 366–369 | date = August 2008 | pmid = 18522922 | pmc = 2610160 | doi = 10.1098/rsbl.2008.0224 }}</ref>

<ref name=KimGraham2008>{{cite journal | author1 = Kim, E. | author2 = Graham, L.E. | title = EEF2 analysis challenges the monophyly of Archaeplastida and Chromalveolata | journal = PLOS ONE | volume = 3 | issue = 7 | article-number = e2621 | date = July 2008 | pmid = 18612431 | pmc = 2440802 | doi = 10.1371/journal.pone.0002621 | doi-access = free }} {{open access}}</ref>

<ref name="ReducingLongBranchAlveolataRhizaria">{{cite journal | author1 = He, D. | author2 = Sierra, R. | author3 = Pawlowski, J. | author4 = Baldauf, S.L. | title = Reducing long-branch effects in multi-protein data uncovers a close relationship between Alveolata and Rhizaria | journal = Molecular Phylogenetics and Evolution | volume = 101 | pages = 1–7 | date = August 2016 | pmid = 27132173 | doi = 10.1016/j.ympev.2016.04.033 | doi-access = free }}</ref>

<ref name="AMolecularTimescale">{{cite journal | author1 = Strassert, J.F. | author2 = Irisarri, I. | author3 = Williams, T.A. | 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 }}</ref>

<ref name="8phyla">{{cite journal |last1=Cavalier-Smith |first1=Thomas |title=Kingdom Chromista and its eight phyla: a new synthesis emphasising periplastid protein targeting, cytoskeletal and periplastid evolution, and ancient divergences |date=2017 |journal=Protoplasma |pages=297–35 7|volume=255 |issue=1 |doi=10.1007/s00709-017-1147-3 |pmid=28875267 |pmc=5756292 |doi-access=free}}</ref>

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Category:Protist taxa