Editing Cyanobacteria (section)

== Evolution ==

=== Earth history ===
{{life timeline}}
[[Stromatolites]] are layered biochemical [[accretion (geology)|accretion]]ary [[structure]]s formed in shallow water by the trapping, binding, and cementation of sedimentary grains by [[biofilm]]s ([[microbial mat]]s) of [[microorganism]]s, especially cyanobacteria.<ref>{{cite journal | vauthors = Riding R |year=2007 |title=The term stromatolite: towards an essential definition |journal=[[Lethaia]] |volume=32 |issue=4 |pages=321–30 |doi=10.1111/j.1502-3931.1999.tb00550.x}}</ref>

Cyanobacteria likely first evolved in a freshwater environment.<ref name=freshwater/> During the [[Precambrian]], stromatolite communities of microorganisms grew in most marine and non-marine environments in the [[photic zone]]. After the Cambrian explosion of marine animals, grazing on the stromatolite mats by herbivores greatly reduced the occurrence of the stromatolites in marine environments. Since then, they are found mostly in hypersaline conditions where grazing invertebrates cannot live (e.g. [[Shark Bay]], Western Australia). Stromatolites provide ancient records of life on Earth by fossil remains which date from 3.5 [[annus#SI prefix multipliers|Ga]] ago.<ref>{{cite journal |last1=Baumgartner |first1=Raphael J. |last2=Van Kranendonk |first2=Martin J. |last3=Wacey |first3=David |last4=Fiorentini |first4=Marco L. |last5=Saunders |first5=Martin |last6=Caruso |first6=Stefano |last7=Pages |first7=Anais |last8=Homann |first8=Martin |last9=Guagliardo |first9=Paul |title=Nano−porous pyrite and organic matter in 3.5-billion-year-old stromatolites record primordial life |journal=Geology |date=November 2019 |volume=47 |issue=11 |pages=1039–1043 |doi=10.1130/G46365.1 |bibcode=2019Geo....47.1039B |url=https://archimer.ifremer.fr/doc/00637/74900/ }}</ref> The oldest undisputed evidence of cyanobacteria is dated to be 2.1 Ga ago, but there is some evidence for them as far back as 2.7 Ga ago.<ref name="Schirrmeister-2013">{{cite journal | vauthors = Schirrmeister BE, de Vos JM, Antonelli A, Bagheri HC | title = Evolution of multicellularity coincided with increased diversification of cyanobacteria and the Great Oxidation Event | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 110 | issue = 5 | pages = 1791–1796 | date = January 2013 | pmid = 23319632 | pmc = 3562814 | doi = 10.1073/pnas.1209927110 | doi-access = free | bibcode = 2013PNAS..110.1791S }}</ref> Cyanobacteria might have also emerged 3.5 Ga ago.<ref>{{cite journal | vauthors = Schopf JW, Packer BM | title = Early Archean (3.3-billion to 3.5-billion-year-old) microfossils from Warrawoona Group, Australia | journal = Science | volume = 237 | issue = 4810 | pages = 70–73 | date = July 1987 | pmid = 11539686 | doi = 10.1126/science.11539686 | bibcode = 1987Sci...237...70S }}</ref> Oxygen concentrations in the atmosphere remained around or below 0.001% of today's level until 2.4 Ga ago (the [[Great Oxygenation Event]]).<ref>{{cite journal | vauthors = Farquhar J, Bao H, Thiemens M | title = Atmospheric influence of Earth's earliest sulfur cycle | journal = Science | volume = 289 | issue = 5480 | pages = 756–759 | date = August 2000 | pmid = 10926533 | doi = 10.1126/science.289.5480.756 | bibcode = 2000Sci...289..756F }}</ref> The rise in oxygen may have caused a fall in the concentration of [[atmospheric methane]], and triggered the [[Huronian glaciation]] from around 2.4 to 2.1 Ga ago. In this way, cyanobacteria may have killed off most of the other bacteria of the time.<ref name=Lane>{{cite news |author-link=Nick Lane | vauthors = Lane N |date=6 February 2010 |url=https://www.newscientist.com/article/mg20527461-100-first-breath-earths-billion-year-struggle-for-oxygen/ |title=First breath: Earth's billion-year struggle for oxygen |work=[[New Scientist]] |pages=36–39 }} See accompanying graph as well.</ref>

[[Oncolite]]s are [[sedimentary structures]] composed of oncoids, which are layered structures formed by cyanobacterial growth. Oncolites are similar to stromatolites, but instead of forming columns, they form approximately spherical structures that were not attached to the underlying substrate as they formed.<ref name=Corsetti2003>{{cite journal | vauthors = Corsetti FA, Awramik SM, Pierce D | title = A complex microbiota from snowball Earth times: microfossils from the Neoproterozoic Kingston Peak Formation, Death Valley, USA | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 100 | issue = 8 | pages = 4399–4404 | date = April 2003 | pmid = 12682298 | pmc = 153566 | doi = 10.1073/pnas.0730560100 | doi-access = free | bibcode = 2003PNAS..100.4399C }}</ref> The oncoids often form around a central nucleus, such as a shell fragment,<ref>{{cite journal |last1=Gutschick |first1=Raymond Charles |last2=Perry |first2=Thomas Gregory |title=Sappington (Kinderhookian) sponges and their environment [Montana] |journal=Journal of Paleontology |date=November 1959 |volume=33 |issue=6 |pages=977–985 |url=https://pubs.geoscienceworld.org/paleosoc/jpaleontol/article/33/6/977/79261/Sappington-Kinderhookian-sponges-and-their }}
</ref> and a [[calcium carbonate]] structure is deposited by encrusting [[microbes]]. Oncolites are indicators of warm waters in the [[photic zone]], but are also known in contemporary freshwater environments.<ref>{{cite book |doi=10.1007/978-3-642-52335-9 |title=Calcareous Algae and Stromatolites |date=1991 |isbn=978-3-642-52337-3 |editor-last1=Riding |editor-first1=Robert |page=32 |publisher=Springer |location=Berlin, Heidelberg }}</ref> These structures rarely exceed 10&nbsp;cm in diameter.

One former classification scheme of cyanobacterial fossils divided them into the [[porostromata]] and the [[spongiostromata]]. These are now recognized as [[form taxa]] and considered taxonomically obsolete; however, some authors have advocated for the terms remaining informally to describe form and structure of bacterial fossils.<ref>{{Cite book | vauthors = Monty CL |chapter=Spongiostromate vs. Porostromate Stromatolites and Oncolites | veditors = Monty CL |title=Phanerozoic Stromatolites  |date=1981 |location=Berlin, Heidelberg |publisher=Springer |pages=1–4 |doi=10.1007/978-3-642-67913-1_1 |isbn=978-3-642-67913-1 }}</ref>

<gallery mode="packed" style="float:left" heights="145px">
File:Stromatolites.jpg| [[Stromatolites]] left behind by cyanobacteria are the oldest known fossils of life on Earth. This fossil is one billion years old.
File:Oncolitic limestone (central Utah, USA) 3.jpg| Oncolitic limestone formed from successive layers of calcium carbonate precipitated by cyanobacteria
File:OncolitesAlamoBreccia.jpg| [[Oncolite]]s from the [[Late Devonian]] [[Alamo bolide impact]] in Nevada
File:Oscillatoriopsis longa fossil.jpg| {{center|Cyanobacterial remains of an annulated tubular [[microfossil]] ''Oscillatoriopsis longa''{{hsp}}<ref>{{cite journal |doi=10.1111/pala.12374 |title=First record of Cyanobacteria in Cambrian Orsten deposits of Sweden |year=2018 | vauthors = Castellani C, Maas A, Eriksson ME, Haug JT, Haug C, Waloszek D |journal=[[Palaeontology (journal)|Palaeontology]] |volume=61 |issue=6 |pages=855–880 |bibcode=2018Palgy..61..855C }}</ref><br /><small>Scale bar: 100 μm</small>}}
</gallery>

{{clear left}}

=== Origin of photosynthesis ===
{{further|Evolution of photosynthesis}}

[[Oxygenic photosynthesis]] only evolved once (in prokaryotic cyanobacteria), and all photosynthetic [[eukaryote]]s (including all [[plant]]s and [[algae]]) have acquired this ability from [[symbiogenesis|endosymbiosis]] with cyanobacteria or their [[endosymbiont]] hosts. In other words, all the oxygen that makes the atmosphere breathable for [[aerobic organism]]s originally comes from cyanobacteria or their [[plastid]] descendants.<ref>{{Cite web |url=https://phys.org/news/2017-03-oxygen-cyanobacteria.html |title=How do plants make oxygen? Ask cyanobacteria |date=30 March 2017 |website=[[Phys.org]] |publisher=Science X |access-date=2017-10-26}}</ref>

Cyanobacteria remained the principal [[primary producers]] throughout the latter half of the [[Archean]] [[eon (geology)|eon]] and most of the [[Proterozoic eon]], in part because the redox structure of the oceans favored photoautotrophs capable of [[nitrogen fixation]]. However, their population is argued to have varied considerably across this eon.<ref name=pwc/><ref>{{Cite journal | vauthors = Crockford PW, Kunzmann M, Bekker A, Hayles J, Bao H, Halverson GP, Peng Y, Bui TH, Cox GM, Gibson TM, Wörndle S | display-authors = 6 |date=2019-05-20 |title=Claypool continued: Extending the isotopic record of sedimentary sulfate |journal=Chemical Geology |volume=513 |pages=200–225 |doi=10.1016/j.chemgeo.2019.02.030 | bibcode = 2019ChGeo.513..200C }}</ref><ref>{{cite journal | vauthors = Hodgskiss MS, Crockford PW, Peng Y, Wing BA, Horner TJ | title = A productivity collapse to end Earth's Great Oxidation | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 116 | issue = 35 | pages = 17207–17212 | date = August 2019 | pmid = 31405980 | pmc = 6717284 | doi = 10.1073/pnas.1900325116 | bibcode = 2019PNAS..11617207H | doi-access = free }}</ref> [[Archaeplastid]]s such as [[green algae|green]] and [[red algae]] eventually surpassed cyanobacteria as major primary producers on [[continental shelf|continental shelves]] near the end of the [[Neoproterozoic]], but only with the [[Mesozoic]] (251–65 Ma) radiations of secondary photoautotrophs such as [[dinoflagellate]]s, [[Coccolithophore|coccolithophorids]] and [[diatom]]s did [[primary production]] in marine shelf waters take modern form. Cyanobacteria remain critical to [[marine ecosystem]]s as primary producers in oceanic gyres, as agents of biological nitrogen fixation, and, in modified form, as the plastids of [[marine algae]].<ref name=Herrero>{{cite book | vauthors = Herrero A | veditors = Flores E |title=The Cyanobacteria: Molecular Biology, Genomics and Evolution |edition=1st |publisher=Caister Academic Press |year=2008 |isbn=978-1-904455-15-8}}</ref>

=== Origin of chloroplasts ===
{{See also|Chloroplast#Chloroplast lineages and evolution}}

Primary chloroplasts are cell organelles found in some [[eukaryote|eukaryotic]] lineages, where they are specialized in performing photosynthesis. They are considered to have evolved from [[endosymbiotic]] cyanobacteria.<ref name="ReferenceA">{{cite journal | vauthors = Keeling PJ | title = The number, speed, and impact of plastid endosymbioses in eukaryotic evolution | journal = Annual Review of Plant Biology | volume = 64 | pages = 583–607 | year = 2013 | issue = 1 | pmid = 23451781 | doi = 10.1146/annurev-arplant-050312-120144 | bibcode = 2013AnRPB..64..583K }}</ref><ref>{{cite journal | vauthors = Moore KR, Magnabosco C, Momper L, Gold DA, Bosak T, Fournier GP | title = An Expanded Ribosomal Phylogeny of Cyanobacteria Supports a Deep Placement of Plastids | journal = Frontiers in Microbiology | volume = 10 | pages = 1612 | date = 2019 | pmid = 31354692 | pmc = 6640209 | doi = 10.3389/fmicb.2019.01612 | doi-access = free }}</ref> After some years of debate,<ref>{{cite journal | vauthors = Howe CJ, Barbrook AC, Nisbet RE, Lockhart PJ, Larkum AW | title = The origin of plastids | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 363 | issue = 1504 | pages = 2675–2685 | date = August 2008 | pmid = 18468982 | pmc = 2606771 | doi = 10.1098/rstb.2008.0050 }}</ref> it is now generally accepted that the three major groups of primary endosymbiotic eukaryotes (i.e. [[Viridiplantae|green plants]], [[Rhodophytes|red algae]] and [[glaucophyte]]s) form one large [[Monophyly|monophyletic group]] called [[Archaeplastida]], which evolved after one unique endosymbiotic event.<ref name="Rodríguez-Ezpeleta N 2005">{{cite journal | vauthors = Rodríguez-Ezpeleta N, Brinkmann H, Burey SC, Roure B, Burger G, Löffelhardt W, Bohnert HJ, Philippe H, Lang BF | display-authors = 6 | title = Monophyly of primary photosynthetic eukaryotes: green plants, red algae, and glaucophytes | journal = Current Biology | volume = 15 | issue = 14 | pages = 1325–1330 | date = July 2005 | pmid = 16051178 | doi = 10.1016/j.cub.2005.06.040 | doi-access = free | bibcode = 2005CBio...15.1325R }}</ref><ref>{{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, 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 = 429–493 | date = September 2012 | pmid = 23020233 | pmc = 3483872 | doi = 10.1111/j.1550-7408.2012.00644.x }}</ref><ref>{{cite journal | vauthors = Price DC, Chan CX, Yoon HS, Yang EC, Qiu H, Weber AP, Schwacke R, Gross J, Blouin NA, Lane C, Reyes-Prieto A, Durnford DG, Neilson JA, Lang BF, Burger G, Steiner JM, Löffelhardt W, Meuser JE, Posewitz MC, Ball S, Arias MC, Henrissat B, Coutinho PM, Rensing SA, Symeonidi A, Doddapaneni H, Green BR, Rajah VD, Boore J, Bhattacharya D | display-authors = 6 | title = Cyanophora paradoxa genome elucidates origin of photosynthesis in algae and plants | journal = Science | volume = 335 | issue = 6070 | pages = 843–847 | date = February 2012 | pmid = 22344442 | doi = 10.1126/science.1213561 | bibcode = 2012Sci...335..843P }}</ref><ref name="Ponce-Toledo RI 2016">{{cite journal | vauthors = Ponce-Toledo RI, Deschamps P, López-García P, Zivanovic Y, Benzerara K, Moreira D | title = An Early-Branching Freshwater Cyanobacterium at the Origin of Plastids | journal = Current Biology | volume = 27 | issue = 3 | pages = 386–391 | date = February 2017 | pmid = 28132810 | pmc = 5650054 | doi = 10.1016/j.cub.2016.11.056 | bibcode = 2017CBio...27..386P }}</ref>

The [[Morphology (biology)|morphological]] similarity between chloroplasts and cyanobacteria was first reported by German botanist [[Andreas Franz Wilhelm Schimper]] in the 19th century<ref name="Schimper">{{cite journal | vauthors = Schimper AF |author-link=Andreas Franz Wilhelm Schimper |title=Über die Entwicklung der Chlorophyllkörner und Farbkörper |trans-title=About the development of the chlorophyll grains and stains |language=de |journal=Bot. Zeitung |year=1883 |volume=41 |pages=105–14, 121–31, 137–46, 153–62 |url=http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/19551 |url-status=dead |archive-url=https://web.archive.org/web/20131019121025/http://publikationen.stub.uni-frankfurt.de/frontdoor/index/index/docId/19551 |archive-date=19 October 2013|df=dmy-all}}</ref> Chloroplasts are only found in [[plant]]s and [[algae]],<ref name="Molecular biology of the cell—chloroplasts and photosynthesis">{{cite book |last1=Alberts |first1=Bruce |last2=Johnson |first2=Alexander |last3=Lewis |first3=Julian |last4=Raff |first4=Martin |last5=Roberts |first5=Keith |last6=Walter |first6=Peter |title=Molecular Biology of the Cell |edition=4th |date=2002 |publisher=Garland Science |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK26819/ |chapter=Chloroplasts and Photosynthesis }}</ref> thus paving the way for Russian biologist [[Konstantin Mereschkowski]] to suggest in 1905 the symbiogenic origin of the plastid.<ref>{{cite journal |vauthors=Mereschkowsky C |title=Über Natur und Ursprung der Chromatophoren im Pflanzenreiche |trans-title=About the nature and origin of chromatophores in the vegetable kingdom |language=de |journal=Biol Centralbl |year=1905 |volume=25 |pages=593–604 |url=https://archive.org/details/cbarchive_51353_bernaturundursprungderchromato1881}}</ref> [[Lynn Margulis]] brought this hypothesis back to attention more than 60 years later<ref>{{cite journal | vauthors = Sagan L | title = On the origin of mitosing cells | journal = Journal of Theoretical Biology | volume = 14 | issue = 3 | pages = 255–274 | date = March 1967 | pmid = 11541392 | doi = 10.1016/0022-5193(67)90079-3 | bibcode = 1967JThBi..14..225S }}</ref> but the idea did not become fully accepted until supplementary data started to accumulate. The cyanobacterial origin of plastids is now supported by various pieces of [[Phylogenetics|phylogenetic]],<ref>{{cite journal | vauthors = Schwartz RM, Dayhoff MO | title = Origins of prokaryotes, eukaryotes, mitochondria, and chloroplasts | journal = Science | volume = 199 | issue = 4327 | pages = 395–403 | date = January 1978 | pmid = 202030 | doi = 10.1126/science.202030 | bibcode = 1978Sci...199..395S }}</ref><ref name="Rodríguez-Ezpeleta N 2005"/><ref name="Ponce-Toledo RI 2016"/> [[Genomics|genomic]],<ref>{{cite journal | vauthors = Archibald JM | title = Genomic perspectives on the birth and spread of plastids | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 112 | issue = 33 | pages = 10147–10153 | date = August 2015 | pmid = 25902528 | pmc = 4547232 | doi = 10.1073/pnas.1421374112 | doi-access = free | bibcode = 2015PNAS..11210147A }}</ref> biochemical<ref>{{cite journal | vauthors = Blankenship RE | title = Early evolution of photosynthesis | journal = Plant Physiology | volume = 154 | issue = 2 | pages = 434–438 | date = October 2010 | pmid = 20921158 | pmc = 2949000 | doi = 10.1104/pp.110.161687 }}</ref><ref>{{cite journal | vauthors = Rockwell NC, Lagarias JC, Bhattacharya D | title = Primary endosymbiosis and the evolution of light and oxygen sensing in photosynthetic eukaryotes | journal = Frontiers in Ecology and Evolution | volume = 2 | issue = 66 | year = 2014 | pmid = 25729749 | pmc = 4343542 | doi = 10.3389/fevo.2014.00066 | doi-access = free | bibcode = 2014FrEEv...2...66R }}</ref> and structural evidence.<ref>Summarised in {{cite journal | vauthors = Cavalier-Smith T | title = Membrane heredity and early chloroplast evolution | journal = Trends in Plant Science | volume = 5 | issue = 4 | pages = 174–182 | date = April 2000 | pmid = 10740299 | doi = 10.1016/S1360-1385(00)01598-3 }}</ref> The description of another independent and more recent primary endosymbiosis event between a cyanobacterium and a separate eukaryote lineage (the [[rhizaria]]n ''[[Paulinella]] chromatophora'') also gives credibility to the endosymbiotic origin of the plastids.<ref>{{cite journal | vauthors = Nowack EC, Melkonian M, Glöckner G | title = Chromatophore genome sequence of Paulinella sheds light on acquisition of photosynthesis by eukaryotes | journal = Current Biology | volume = 18 | issue = 6 | pages = 410–418 | date = March 2008 | pmid = 18356055 | doi = 10.1016/j.cub.2008.02.051 | doi-access = free | bibcode = 2008CBio...18..410N }}</ref>

{{multiple image |total_width=450|caption_align = center
|image1=Glaucocystis sp.jpg |caption1=The chloroplasts of [[glaucophyte]]s have a [[peptidoglycan]] layer, evidence suggesting their endosymbiotic origin from cyanobacteria.<ref name="keeling">{{cite journal | vauthors = Keeling PJ | title = Diversity and evolutionary history of plastids and their hosts | journal = American Journal of Botany | volume = 91 | issue = 10 | pages = 1481–1493 | date = October 2004 | pmid = 21652304 | doi = 10.3732/ajb.91.10.1481 | doi-access = free | bibcode = 2004AmJB...91.1481K }}</ref>
|image2=Plagiomnium affine laminazellen.jpeg |caption2=Plant cells with visible chloroplasts (from a moss, ''[[Plagiomnium affine]]'')
}}
In addition to this primary endosymbiosis, many eukaryotic lineages have been subject to [[Secondary endosymbiosis|secondary]] or even [[tertiary endosymbiotic events]], that is the "[[Matryoshka doll|Matryoshka]]-like" engulfment by a eukaryote of another plastid-bearing eukaryote.<ref>{{cite journal | vauthors = Archibald JM | title = The puzzle of plastid evolution | journal = Current Biology | volume = 19 | issue = 2 | pages = R81–R88 | date = January 2009 | pmid = 19174147 | doi = 10.1016/j.cub.2008.11.067 | doi-access = free | bibcode = 2009CBio...19..R81A }}</ref><ref name="ReferenceA"/>

[[Chloroplast]]s have many similarities with cyanobacteria, including a circular [[chromosome]], prokaryotic-type [[ribosome]]s, and similar proteins in the photosynthetic reaction center.<ref>{{cite journal | vauthors = Douglas SE | title = Plastid evolution: origins, diversity, trends | journal = Current Opinion in Genetics & Development | volume = 8 | issue = 6 | pages = 655–661 | date = December 1998 | pmid = 9914199 | doi = 10.1016/S0959-437X(98)80033-6 }}</ref><ref>{{cite journal | vauthors = Reyes-Prieto A, Weber AP, Bhattacharya D | title = The origin and establishment of the plastid in algae and plants | journal = Annual Review of Genetics | volume = 41 | pages = 147–168 | year = 2007 | issue = 1 | pmid = 17600460 | doi = 10.1146/annurev.genet.41.110306.130134 }}</ref> The [[endosymbiotic theory]] suggests that photosynthetic bacteria were acquired (by [[endocytosis]]) by early [[Eukaryote|eukaryotic]] cells to form the first [[plant]] cells. Therefore, chloroplasts may be photosynthetic bacteria that adapted to life inside plant cells. Like [[mitochondrion|mitochondria]], chloroplasts still possess their own DNA, separate from the [[nuclear DNA]] of their plant host cells and the genes in this chloroplast DNA resemble those in cyanobacteria.<ref>{{cite journal | vauthors = Raven JA, Allen JF | title = Genomics and chloroplast evolution: what did cyanobacteria do for plants? | journal = Genome Biology | volume = 4 | issue = 3 | pages = 209 | year = 2003 | pmid = 12620099 | pmc = 153454 | doi = 10.1186/gb-2003-4-3-209 | doi-access = free }}</ref> DNA in chloroplasts codes for [[redox]] proteins such as photosynthetic reaction centers. The [[CoRR hypothesis]] proposes this co-location is required for redox regulation.

=== Origin of marine planktonic cyanobacteria ===
[[File:Timing and trends in cell diameter, loss of filamentous forms and habitat preference within cyanobacteria.webp|thumb|upright=1.5|left|{{center|Timing and trends in cell diameter, loss of filamentous forms and habitat preference within cyanobacteria}} Based on data: nodes (1–10) and stars representing common ancestors from Sánchez-Baracaldo et al., 2015,<ref name="Sánchez-Baracaldo2016">{{cite journal | vauthors = Sánchez-Baracaldo P | title = Origin of marine planktonic cyanobacteria | journal = Scientific Reports | volume = 5 | pages = 17418 | date = December 2015 | issue = 1 | pmid = 26621203 | pmc = 4665016 | doi = 10.1038/srep17418 | bibcode = 2015NatSR...517418S }} {{Creative Commons text attribution notice|cc=by4|from this source=yes}}</ref> timing of the [[Great Oxidation Event]] (GOE),<ref name="Bekker2004">{{cite journal | vauthors = Bekker A, Holland HD, Wang PL, Rumble D, Stein HJ, Hannah JL, Coetzee LL, Beukes NJ | display-authors = 6 | title = Dating the rise of atmospheric oxygen | journal = Nature | volume = 427 | issue = 6970 | pages = 117–120 | date = January 2004 | pmid = 14712267 | doi = 10.1038/nature02260 | bibcode = 2004Natur.427..117B }}</ref> the [[Lomagundi-Jatuli Excursion]],<ref>{{cite journal | vauthors = Kump LR, Junium C, Arthur MA, Brasier A, Fallick A, Melezhik V, Lepland A, Crne AE, Luo G | display-authors = 6 | title = Isotopic evidence for massive oxidation of organic matter following the great oxidation event | journal = Science | volume = 334 | issue = 6063 | pages = 1694–1696 | date = December 2011 | pmid = 22144465 | doi = 10.1126/science.1213999 | doi-access = free | bibcode = 2011Sci...334.1694K }}</ref> and [[Gunflint formation]].<ref>{{cite journal |doi=10.1139/e02-028 |title=The age of the Gunflint Formation, Ontario, Canada: Single zircon U–Pb age determinations from reworked volcanic ash |year=2002 | vauthors = Fralick P, Davis DW, Kissin SA |journal=Canadian Journal of Earth Sciences |volume=39 |issue=7 |pages=1085–1091 |bibcode=2002CaJES..39.1085F}}</ref> Green lines represent freshwater lineages and blue lines represent marine lineages are based on Bayesian inference of character evolution (stochastic character mapping analyses).<ref name="Sánchez-Baracaldo2016" /> {{center|<small>Taxa are not drawn to scale – those with smaller cell diameters are at the bottom and larger at the top</small>}}]]

{{plankton sidebar|taxonomy}}

Cyanobacteria have fundamentally transformed the geochemistry of the planet.<ref name=Holland2006>{{cite journal | vauthors = Holland HD | title = The oxygenation of the atmosphere and oceans | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 361 | issue = 1470 | pages = 903–915 | date = June 2006 | pmid = 16754606 | pmc = 1578726 | doi = 10.1098/rstb.2006.1838 }}</ref><ref name="Bekker2004"/> Multiple lines of geochemical evidence support the occurrence of intervals of profound global environmental change at the beginning and end of the [[Proterozoic]] (2,500–542 Mya).<ref name=Planavsky2014>{{cite journal | vauthors = Planavsky NJ, Reinhard CT, Wang X, Thomson D, McGoldrick P, Rainbird RH, Johnson T, Fischer WW, Lyons TW | display-authors = 6 | title = Earth history. Low mid-Proterozoic atmospheric oxygen levels and the delayed rise of animals | journal = Science | volume = 346 | issue = 6209 | pages = 635–638 | date = October 2014 | pmid = 25359975 | doi = 10.1126/science.1258410 | bibcode = 2014Sci...346..635P | url = https://resolver.caltech.edu/CaltechAUTHORS:20141009-185334240 }}</ref>
<ref name=Lyons2014>{{cite journal | vauthors = Lyons TW, Reinhard CT, Planavsky NJ | title = The rise of oxygen in Earth's early ocean and atmosphere | journal = Nature | volume = 506 | issue = 7488 | pages = 307–315 | date = February 2014 | pmid = 24553238 | doi = 10.1038/nature13068 | bibcode = 2014Natur.506..307L }}</ref><ref name=Sahoo2012>{{cite journal | vauthors = Sahoo SK, Planavsky NJ, Kendall B, Wang X, Shi X, Scott C, Anbar AD, Lyons TW, Jiang G | display-authors = 6 | title = Ocean oxygenation in the wake of the Marinoan glaciation | journal = Nature | volume = 489 | issue = 7417 | pages = 546–549 | date = September 2012 | pmid = 23018964 | doi = 10.1038/nature11445 | bibcode = 2012Natur.489..546S }}</ref> While it is widely accepted that the presence of molecular oxygen in the early fossil record was the result of cyanobacteria activity, little is known about how cyanobacteria evolution (e.g., habitat preference) may have contributed to changes in [[biogeochemical cycle]]s through Earth history. Geochemical evidence has indicated that there was a first step-increase in the oxygenation of the Earth's surface, which is known as the [[Great Oxidation Event]] (GOE), in the early [[Paleoproterozoic]] (2,500–1,600 Mya).<ref name=Holland2006 /><ref name=Bekker2004 /> A second but much steeper increase in oxygen levels, known as the Neoproterozoic Oxygenation Event (NOE),<ref name=Lyons2014 /><ref name="Och_2012" /><ref name=Canfield2007>{{cite journal | vauthors = Canfield DE, Poulton SW, Narbonne GM | title = Late-Neoproterozoic deep-ocean oxygenation and the rise of animal life | journal = Science | volume = 315 | issue = 5808 | pages = 92–95 | date = January 2007 | pmid = 17158290 | doi = 10.1126/science.1135013 | bibcode = 2007Sci...315...92C | doi-access = free }}</ref> occurred at around 800 to 500 Mya.<ref name=Sahoo2012 /><ref name=Fike2006>{{cite journal | vauthors = Fike DA, Grotzinger JP, Pratt LM, Summons RE | title = Oxidation of the Ediacaran ocean | journal = Nature | volume = 444 | issue = 7120 | pages = 744–747 | date = December 2006 | pmid = 17151665 | doi = 10.1038/nature05345 | bibcode = 2006Natur.444..744F | url = https://resolver.caltech.edu/CaltechAUTHORS:20130212-145114208 }}</ref> Recent [[chromium]] isotope data point to low levels of atmospheric oxygen in the Earth's surface during the mid-Proterozoic,<ref name=Planavsky2014 /> which is consistent with the late evolution of marine planktonic cyanobacteria during the [[Cryogenian]];<ref name="Sánchez-Baracaldo2014">{{cite journal | vauthors = Sánchez-Baracaldo P, Ridgwell A, Raven JA | title = A neoproterozoic transition in the marine nitrogen cycle | journal = Current Biology | volume = 24 | issue = 6 | pages = 652–657 | date = March 2014 | pmid = 24583016 | doi = 10.1016/j.cub.2014.01.041 | doi-access = free | bibcode = 2014CBio...24..652S }}</ref> both types of evidence help explain the late emergence and diversification of animals.<ref name=Erwin2011>{{cite journal | vauthors = Erwin DH, Laflamme M, Tweedt SM, Sperling EA, Pisani D, Peterson KJ | title = The Cambrian conundrum: early divergence and later ecological success in the early history of animals | journal = Science | volume = 334 | issue = 6059 | pages = 1091–1097 | date = November 2011 | pmid = 22116879 | doi = 10.1126/science.1206375 | bibcode = 2011Sci...334.1091E }}</ref><ref name="Sánchez-Baracaldo2016" />

Understanding the evolution of planktonic cyanobacteria is important because their origin fundamentally transformed the [[nitrogen cycle|nitrogen]] and [[carbon cycle]]s towards the end of the [[Pre-Cambrian]].<ref name=Fike2006 /> It remains unclear, however, what evolutionary events led to the emergence of open-ocean planktonic forms within cyanobacteria and how these events relate to geochemical evidence during the Pre-Cambrian.<ref name=Lyons2014 /> So far, it seems that ocean geochemistry (e.g., [[euxinic]] conditions during the early- to mid-Proterozoic)<ref name=Lyons2014 /><ref name=Canfield2007 /><ref>{{cite journal |doi=10.2113/gselements.7.2.107 |title=Ferruginous Conditions: A Dominant Feature of the Ocean through Earth's History |year=2011 | vauthors = Poulton SW, Canfield DE |journal=Elements |volume=7 |issue=2 |pages=107–112|bibcode=2011Eleme...7..107P }}</ref> and nutrient availability{{hsp}}<ref>{{cite journal | vauthors = Anbar AD, Knoll AH | title = Proterozoic ocean chemistry and evolution: a bioinorganic bridge? | journal = Science | volume = 297 | issue = 5584 | pages = 1137–1142 | date = August 2002 | pmid = 12183619 | doi = 10.1126/science.1069651 | bibcode = 2002Sci...297.1137A }}</ref> likely contributed to the apparent delay in diversification and widespread colonization of open ocean environments by planktonic cyanobacteria during the [[Neoproterozoic]].<ref name=Fike2006 /><ref name="Sánchez-Baracaldo2016" />
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