Editing Ginkgo biloba (section)

====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}}