View source for Biology:Amorphea

{{Short description|Members of the Unikonta, a taxonomic group proposed by Thomas Cavalier-Smith}}
{{Automatic taxobox
| image = <imagemap>
File:Unikonta collage.jpg|240px

rect 0 0 950 1200 Ichtyosporea
rect 0 1200 1320 2160 Amebozoa
rect 0 2160 1305 3500 [[Biology:Nucleariida|Nucleariida]]
rect 950 0 2550 1200 [[Biology:Fungus|Fungus]]
rect 1320 1200 2550 2160 Choanoflegellate
rect 1305 2160 2550 3500 [[Biology:Animal|Animal]]

</imagemap>
| taxon = Amorphea
| fossil_range = Early [[Earth:Ectasian|Ectasian]] - [[Earth:Holocene|Present]], {{long fossil range|1400|0}}
| authority = Adl ''et al.'', 2012<ref name="Adl2012"/>
| subdivision_ranks = Subgroups
| subdivision = 
*[[Biology:Obazoa|Obazoa]]
**[[Biology:Breviatea|Breviatea]]
**[[Biology:Apusomonadida|Apusomonadida]]
**Opisthokonts
***[[Biology:Holomycota|Holomycota]]
***[[Biology:Holozoa|Holozoa]]
*[[Biology:Amoebozoa|Amoebozoa]]
 | synonyms =
* '''Unikonta''' <small>''[[Biology:Nomen nudum|nom. nud.]]''</small><ref name="pmid11931142"/>
* '''Opimoda''' <small>Derelle et al., 2015</small><ref>{{Cite journal|title = Bacterial proteins pinpoint a single eukaryotic root|journal = Proceedings of the National Academy of Sciences|date = 17 February 2015 |pmc = 4343179|pmid = 25646484|pages = E693–E699|volume = 112|issue = 7|doi = 10.1073/pnas.1420657112|language = en|first1 = Romain|last1 = Derelle|first2 = Guifré|last2 = Torruella|first3 = Vladimír|last3 = Klimeš|first4 = Henner|last4 = Brinkmann|first5 = Eunsoo|last5 = Kim|first6 = Čestmír|last6 = Vlček|first7 = B. Franz|last7 = Lang|first8 = Marek|last8 = Eliáš|bibcode = 2015PNAS..112E.693D|doi-access = free}}</ref> }}

'''Amorphea'''<ref name="Adl2012"/> is a taxonomic supergroup that includes the basal [[Biology:Amoebozoa|Amoebozoa]] and [[Biology:Obazoa|Obazoa]]. That latter contains the [[Biology:Opisthokont|Opisthokont]]a, which includes the [[Biology:Fungus|Fungi]], [[Biology:Animal|Animal]]s and the Choanomonada, or [[Biology:Choanoflagellate|Choanoflagellate]]s. The taxonomic affinities of the members of this clade were originally described and proposed by [[Biography:Thomas Cavalier-Smith|Thomas Cavalier-Smith]] in 2002.<ref name="pmid11931142">{{cite journal |author=Cavalier-Smith T |title=The phagotrophic origin of eukaryotes and phylogenetic classification of Protozoa |journal=Int. J. Syst. Evol. Microbiol. |volume=52 |issue=Pt 2 |pages=297–354 |date=March 2002 |pmid=11931142 |doi= 10.1099/00207713-52-2-297|url=http://ijs.sgmjournals.org/cgi/pmidlookup?view=long&pmid=11931142}}</ref><ref>{{cite journal |  first = Thomas | last = Cavalier-Smith | title = Protist phylogeny and the high-level classification of Protozoa | journal = European Journal of Protistology | year = 2003 | volume = 39 | issue = 4 | pages = 338–348 | doi = 10.1078/0932-4739-00002}}</ref>

The International Society of Protistologists, the recognised body for taxonomy of protozoa, recommended in 2012 that the term Unikont be changed to Amorphea because the name "Unikont" is based on a hypothesized synapomorphy that the ISOP authors and other scientists later rejected.<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 RS, Schoch CL, Smirnov A, Spiegel FW | date = September 2012 | title = The revised classification of eukaryotes | journal = J Eukaryot Microbiol | volume = 59 | issue = 5| pages = 429–93 | doi = 10.1111/j.1550-7408.2012.00644.x | pmid=23020233 | pmc=3483872}}</ref><ref name=Roger2009>{{cite journal |vauthors=Roger AJ, Simpson AG | year = 2009| title = Evolution: revisiting the root of the eukaryote tree | journal = Current Biology | volume = 19| issue = 4 | pages = R165–R167 | doi = 10.1016/j.cub.2008.12.032 | pmid=19243692 | s2cid = 13172971| doi-access = free }}</ref>

It includes [[Biology:Amoebozoa|amoebozoa]], [[Biology:Opisthokont|opisthokont]]s,<ref name="pmid19004754">{{cite journal |vauthors=A Minge M, Silberman JD, Orr RJ, etal |title=Evolutionary position of breviate amoebae and the primary eukaryote divergence |journal=Proc. Biol. Sci. |volume= 276|issue= 1657|pages= 597–604|date=November 2008 |pmid=19004754 |doi=10.1098/rspb.2008.1358 |pmc=2660946}}</ref><ref name="pmid16829542">{{cite journal |vauthors=Burki F, Pawlowski J |title=Monophyly of Rhizaria and multigene phylogeny of unicellular bikonts |journal=Mol. Biol. Evol. |volume=23 |issue=10 |pages=1922–30 |date=October 2006 |pmid=16829542 |doi=10.1093/molbev/msl055 |doi-access= }}</ref> and [[Biology:Apusozoa|Apusomonada.]]<ref>{{Cite journal |last1=Burki |first1=Fabien |last2=Roger |first2=Andrew J. |last3=Brown |first3=Matthew W. |last4=Simpson |first4=Alastair G. B. |date=2020-01-01 |title=The New Tree of Eukaryotes |journal=Trends in Ecology & Evolution |volume=35 |issue=1 |pages=43–55 |doi=10.1016/j.tree.2019.08.008 |pmid=31606140 |issn=0169-5347|doi-access=free }}</ref>

==Taxonomic revisions within this group==

[[Biography:Thomas Cavalier-Smith|Thomas Cavalier-Smith]] proposed two new phyla: Sulcozoa, which consists of the subphyla [[Biology:Apusozoa|Apusozoa]] ([[Biology:Apusomonadida|Apusomonadida]] and [[Biology:Breviatea|Breviatea]]), and [[Biology:Varisulca|Varisulca]], which includes the subphyla [[Biology:Collodictyonidae|Diphyllatea]], Discocelida, Mantamonadidae, Planomonadida and Rigifilida.<ref name=Cavalier-Smith2013>{{cite journal | author=Cavalier-Smith T | date=May 2013 | title=Early evolution of eukaryote feeding modes, cell structural diversity, and classification of the protozoan phyla Loukozoa, Sulcozoa, and Choanozoa | journal=Eur J Protistol | volume=49 | issue=2| pages=115–78 | doi=10.1016/j.ejop.2012.06.001 | pmid=23085100}}</ref>

Further work by Cavalier-Smith showed that Sulcozoa is paraphyletic.<ref name=Cavalier-Smith2014>{{cite journal |vauthors=Cavalier-Smith T, Chao EE, Snell EA, Berney C, Fiore-Donno AM, Lewis R | date=December 2014 | title=Multigene eukaryote phylogeny reveals the likely protozoan ancestors of opisthokonts (animals, fungi, choanozoans) and Amoebozoa | journal=Mol Phylogenet Evol | volume=81 | pages=71–85 | doi=10.1016/j.ympev.2014.08.012 | pmid=25152275| doi-access=free }}</ref> Apusozoa also appears to be paraphyletic. [[Biology:Varisulca|Varisulca]] has been redefined to include planomonads, Mantamonas and [[Biology:Collodictyon|Collodictyon]]. A new taxon has been created - Glissodiscea - for the planomonads and Mantamonas. Again, the validity of this revised taxonomy awaits confirmation.

Amoebozoa seems to be monophyletic with two major branches: [[Biology:Conosa|Conosa]] and [[Biology:Lobosa|Lobosa]]. Conosa is divided into the aerobic infraphylum Semiconosia ([[Biology:Mycetozoa|Mycetozoa]] and Variosea) and secondarily anaerobic [[Biology:Archamoebae|Archamoebae]]. Lobosa consists entirely of non-flagellated lobose amoebae and has been divided into two classes: [[Biology:Discosea|Discosea]], which have flattened cells, and [[Biology:Tubulinea|Tubulinea]], which has predominantly tube-shaped pseudopodia.<ref name=Cavalier-Smith2015>{{cite journal |vauthors=Cavalier-Smith T, Fiore-Donno AM, Chao E, Kudryavtsev A, Berney C, Snell EA, Lewis R | date=February 2015 | title=Multigene phylogeny resolves deep branching of Amoebozoa | journal=Mol Phylogenet Evol | volume=83 | pages=293–304 | doi=10.1016/j.ympev.2014.08.011 | pmid=25150787| doi-access=free }}</ref>

==Clade==
The group includes [[Biology:Eukaryote|eukaryotic]] cells that, for the most part, have a single emergent [[Biology:Flagellum|flagellum]], or are amoebae with no flagella. The unikonts include opisthokonts ([[Biology:Animal|animal]]s, [[Biology:Fungus|fungi]], and related forms) and [[Biology:Amoebozoa|Amoebozoa]]. By contrast, other well-known eukaryotic groups, which more often have two emergent flagella (although there are many exceptions), are often referred to as bikonts.  Bikonts include [[Biology:Archaeplastida|Archaeplastida]] (plants and relatives) and [[Biology:SAR supergroup|SAR supergroup]], the Cryptista, Haptista, [[Biology:Telonemia|Telonemia]] and [[Biology:Picozoa|picozoa]].

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==Characteristics==
The unikonts have a triple-gene fusion that is lacking in the bikonts. The three genes that are [[Biology:Fusion gene|fused together]] in the unikonts, but not bacteria or bikonts, encode enzymes for synthesis of the [[Chemistry:Pyrimidine|pyrimidine]] [[Biology:Nucleotide|nucleotide]]s: carbamoyl phosphate synthase, [[Biology:Dihydroorotase|dihydroorotase]], [[Biology:Aspartate carbamoyltransferase|aspartate carbamoyltransferase]]. This must have involved a double fusion, a rare pair of events, supporting the shared ancestry of Opisthokonta and Amoebozoa.

Cavalier-Smith<ref name="pmid11931142"/> originally proposed that unikonts ancestrally had a single flagellum and single [[Biology:Basal body|basal body]]. This is unlikely, however, as flagellated opisthokonts, as well as some flagellated Amoebozoa, including ''[[Biology:Breviata|Breviata]]'', actually have two basal bodies, as in typical 'bikonts' (even though only one is flagellated in most unikonts). This paired arrangement can also be seen in the organization of centrioles in typical animal cells. In spite of the name of the group, the common ancestor of all 'unikonts' was probably a cell with two basal bodies.

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==References==
{{Reflist|30em}}

==External links==
* {{Cite web | url=http://tolweb.org/Eukaryotes/3 | title=Eukaryotes}} Tree of Life.org

{{Eukaryota classification}}
{{Taxonbar|from=Q474156|from2=Q964455}}

[[Category:Amorphea| ]]

{{Sourceattribution|Amorphea}}