Editing Ginkgo biloba (section)

===Phylogeny===
[[File:Baiera.jpg|thumb|A digital recreation of ''Baiera'' made from diverse images of fossils and academic descriptions]]

''Ginkgo biloba'' is a [[living fossil]], with fossils recognisably related to modern ginkgo from the early [[Permian]] ([[Cisuralian]]), with likely oldest record being that of ''[[Trichopitys]]'' from the earliest Permian ([[Asselian]]) of France, over 290 million years old.<ref name="Zhou-2009">{{cite journal |last=Zhou |first=Zhi-Yan |date=March 2009 |title=An overview of fossil Ginkgoales |url=https://linkinghub.elsevier.com/retrieve/pii/S1871174X0900002X |journal=Palaeoworld |language=en |volume=18 |issue=1 |pages=1–22 |doi=10.1016/j.palwor.2009.01.001 |quote=}}</ref> The closest living relatives of the [[clade]] are the [[cycads]],<ref name=royer/>{{rp|84}} which share with the extant ''G. biloba'' the characteristic of [[motility|motile]] sperm.

Such plants with leaves that have more than four [[leaf#Veins|veins]] per segment have customarily been assigned to the taxon ''Ginkgo'', while the taxon ''[[Baiera]]'' is used to classify those with fewer than four veins per segment. ''[[Sphenobaiera]]'' has been used for plants with a broadly wedge-shaped leaf that lacks a distinct leaf stem.<ref>{{Cite journal |last1=Unverfärth |first1=Jan |last2=McLoughlin |first2=Stephen |last3=Möllmann |first3=Magali |last4=Bomfleur |first4=Benjamin |date=2022-10-02 |title=Sphenobaiera insecta from the Upper Triassic of South Australia, with a clarification of the genus Sphenobaiera (fossil Ginkgophyta) and its delimitation from similar foliage genera |url=https://www.tandfonline.com/doi/full/10.1080/23818107.2022.2076259 |journal=Botany Letters |language=en |volume=169 |issue=4 |pages=442–453 |doi=10.1080/23818107.2022.2076259 |bibcode=2022BotL..169..442U |issn=2381-8107}}</ref><ref>{{Cite journal |last1=Wang |first1=Yongdong |last2=Guignard |first2=Gaëtan |last3=Thévenard |first3=Frédéric |last4=Dilcher |first4=David |last5=Barale |first5=Georges |last6=Mosbrugger |first6=Volker |last7=Yang |first7=Xiaoju |last8=Mei |first8=Shengwu |date=2005 |title=Cuticular anatomy of Sphenobaiera huangii (Ginkgoales) from the Lower Jurassic of Hubei, China |url=https://bsapubs.onlinelibrary.wiley.com/doi/10.3732/ajb.92.4.709 |journal=American Journal of Botany |language=en |volume=92 |issue=4 |pages=709–721 |doi=10.3732/ajb.92.4.709 |pmid=21652450 |issn=0002-9122}}</ref>

====Rise and decline====
[[File:Ginkgo biloba MacAbee BC.jpg|thumb|''Ginkgo biloba'' leaf from the [[Eocene]] epoch from the [[McAbee Fossil Beds]], [[British Columbia]]]]

Fossils attributable to the genus ''Ginkgo'' first appeared in the [[Middle Jurassic]]. The genus ''Ginkgo'' diversified and spread throughout [[Laurasia]] during the [[Jurassic]] and [[Early Cretaceous]].<ref name="Zhou-2009"/>

The Ginkgophyta declined in diversity as the Cretaceous progressed, and by the [[Paleocene]], ''[[Ginkgo adiantoides]]'' was the only ''Ginkgo'' species left in the [[Northern Hemisphere]], while a markedly different (and poorly documented) form persisted in the [[Southern Hemisphere]]. Along with that of ferns, cycads, and cycadeoids, the species diversity in the genus ''Ginkgo'' drops through the Cretaceous, at the same time the flowering plants were on the rise; this supports the hypothesis that, over time, flowering plants with better adaptations to disturbance displaced ''Ginkgo'' and its associates.<ref name=royer/>{{rp|93}}

At the end of the [[Pliocene]], ''Ginkgo'' fossils disappeared from the fossil record everywhere except in a small area of [[South Central China|central China]], where the modern species survived.

====Limited number of species====
[[File:Fossil Plant Ginkgo.jpg|thumb|Fossil ''Ginkgo'' leaves from a [[Jurassic]] period [[geological formation|formation]] in [[Scarborough, North Yorkshire|Scarborough]], UK]]

It is doubtful whether the Northern Hemisphere fossil species of ''Ginkgo'' can be reliably distinguished. Given the slow pace of evolution and morphological similarity between members of the genus, there may have been only one or two species existing in the Northern Hemisphere through the entirety of the [[Cenozoic]]: present-day ''G.&nbsp;biloba'' (including ''G.&nbsp;adiantoides'') and ''[[Ginkgo gardneri|G.&nbsp;gardneri]]'' from the [[Paleocene]] of [[Scotland]].<ref name=royer/>{{rp|85}}

At least morphologically, ''G. gardneri'' and the Southern Hemisphere species are the only known post-Jurassic taxa that can be unequivocally recognised. The remainder may have been [[ecotype]]s or [[subspecies]]. The implications would be that ''G. biloba'' had occurred over an extremely wide range, had remarkable genetic flexibility and, though [[evolution|evolving]] genetically, never showed much [[speciation]].<ref>{{Cite journal |last1=Zhao |first1=Yun-Peng |last2=Fan |first2=Guangyi |last3=Yin |first3=Ping-Ping |last4=Sun |first4=Shuai |last5=Li |first5=Ning |last6=Hong |first6=Xiaoning |last7=Hu |first7=Gang |last8=Zhang |first8=He |last9=Zhang |first9=Fu-Min |last10=Han |first10=Jing-Dan |last11=Hao |first11=Ya-Jun |last12=Xu |first12=Qiwu |last13=Yang |first13=Xianwei |last14=Xia |first14=Wenjie |last15=Chen |first15=Wenbin |date=2019-09-13 |title=Resequencing 545 ginkgo genomes across the world reveals the evolutionary history of the living fossil |journal=Nature Communications |volume=10 |issue=1 |pages=4201 |doi=10.1038/s41467-019-12133-5 |issn=2041-1723 |pmc=6744486 |pmid=31519986|bibcode=2019NatCo..10.4201Z }}</ref><ref>{{Cite journal |last1=Gong |first1=Wei |last2=Chen |first2=Chuan |last3=Dobes |first3=Christoph |last4=Fu |first4=Cheng-Xin |last5=Koch |first5=Marcus A. |date=2008 |title=Phylogeography of a living fossil: pleistocene glaciations forced Ginkgo biloba L. (Ginkgoaceae) into two refuge areas in China with limited subsequent postglacial expansion |url=https://www.sciencedirect.com/science/article/abs/pii/S1055790308002194 |journal=Molecular Phylogenetics and Evolution |volume=48 |issue=3 |pages=1094–1105 |doi=10.1016/j.ympev.2008.05.003 |issn=1095-9513 |pmid=18554931|bibcode=2008MolPE..48.1094G }}</ref>

While it may seem improbable that a single species may exist as a contiguous entity for many millions of years, many of the ginkgo's life-history parameters fit: Extreme longevity; slow reproduction rate; (in Cenozoic and later times) a wide, apparently contiguous, but steadily contracting distribution; and (as far as can be demonstrated from the fossil record) extreme ecological conservatism (restriction to disturbed streamside environments).<ref name=royer/>{{rp|91}}

====Adaptation to a single environment====
Given the slow rate of evolution of the genus, ''Ginkgo'' possibly represents a pre-[[angiosperm]] strategy for survival in disturbed streamside environments. ''Ginkgo'' evolved in an era before flowering plants, when [[fern]]s, [[cycad]]s, and [[Bennettitales|cycadeoids]] dominated disturbed streamside environments, forming low, open, shrubby canopies. ''Ginkgo''{{'s}} large seeds and habit of "bolting" – growing to a height of 10&nbsp;meters before elongating its side branches – may be adaptations to such an environment.

Modern-day ''G. biloba'' grows best in environments that are well-watered and drained,<ref name=royer/>{{rp|87}} and the extremely similar fossil ''Ginkgo'' favored similar environments: The sediment record at the majority of fossil ''Ginkgo'' localities indicates it grew primarily in [[disturbance (ecology)|disturbed environments]], such as along streams.<ref name=royer/> ''Ginkgo'', therefore, presents an "ecological paradox" because while it possesses some favorable traits for living in disturbed environments (clonal reproduction) many of its other life-history traits are the opposite of those exhibited by modern plants that thrive in disturbed settings (slow growth, large seed size, late reproductive maturity).<ref name=royer/>{{rp|92}}