Editing Gunnera (section)

=== Evolution ===
''Gunnera'' is thought to be a rather ancient group, with a well-documented fossil history due to the presence of fossilized [[pollen]] spores, known by the [[palynotaxon]] ''[[Tricolpites reticulatus]]''. It is a [[Gondwana]]n lineage, having originated in [[South America]] during the [[Cretaceous]]. The earliest fossilized pollen is known from the [[Late Cretaceous]] ([[Turonian]]) of Peru, about 90 million years ago, and within the following 10 million years, ''Gunnera'' had achieved a worldwide distribution, with fossil pollen grains being found in areas where it is not found today, such as western [[North America]], mainland [[Australia]], and [[Antarctica]].<ref>{{Cite journal | vauthors = Jarzen DM |date=1980 |title=The Occurrence of ''Gunnera'' Pollen in the Fossil Record |url=https://www.jstor.org/stable/2387727 |journal=Biotropica |volume=12 |issue=2 |pages=117–123 |doi=10.2307/2387727 |jstor=2387727 |bibcode=1980Biotr..12..117J |issn=0006-3606|url-access=subscription }}</ref><ref name=":0">{{cite journal | vauthors = Bacon CD, Velásquez-Puentes FJ, Hinojosa LF, Schwartz T, Oxelman B, Pfeil B, Arroyo MT, Wanntorp L, Antonelli A | display-authors = 6 | title = Evolutionary persistence in ''Gunnera'' and the contribution of southern plant groups to the tropical Andes biodiversity hotspot | journal = PeerJ | volume = 6 | pages = e4388 | date = 2018-03-16 | pmid = 29576938 | pmc = 5858603 | doi = 10.7717/peerj.4388 | doi-access = free }}</ref> Based on fossil pollen recovered from drilling cores, ''Gunnera'' is also known to have inhabited the now-submerged islands of the [[Ninety East Ridge|Ninetyeast Ridge]] during the [[Paleocene]], likely having dispersed there from either [[Australasia]] or the then-emergent [[Kerguelen Plateau]] islands.<ref>{{Cite journal | vauthors = Carpenter RJ, Truswell EM, Harris WK |date=2010-03-02 |title=Lauraceae fossils from a volcanic Palaeocene oceanic island, Ninetyeast Ridge, Indian Ocean: ancient long-distance dispersal?: Indian Ocean Lauraceae fossils |journal=Journal of Biogeography |language=en |volume=37 |issue=7 |pages=1202–1213 |doi=10.1111/j.1365-2699.2010.02279.x |s2cid=83060879}}</ref>

Due to the widespread distribution of ''Gunnera'' during the Cretaceous, it was previously thought that the modern disjunct distribution of the genus was a relic of this period. However, phylogenetic analysis indicates that the majority of ''Gunnera'' species, even those found on entirely different continents, diverged from each other during the [[Cenozoic]], indicating that the modern distribution of ''Gunnera'' is a consequence of [[Long distance dispersal|long-distance dispersal]] from South America to other parts of the world, rather than relics of a former cosmopolitan distribution. The only species that diverged prior to the Cenozoic is ''[[Gunnera herteri]]'', described from Uruguay<ref>{{Cite journal | vauthors = Osten C |date=1932 |title=Una Gunnera en el Uruguay: Gunnera Herteri Osten n. sp. |journal= Herbarium Cornelius Osten Comunicaciones (Montevideo) |language=es |volume=1 |issue=2 |pages=33–39 }}</ref> and distributed in Uruguay and southeastern [[Brazil]], which is thought to be the most ancient species of the genus, its lineage having diverged during the Late Cretaceous, roughly concurrent with the oldest ''Gunnera'' fossil pollen from Peru. The persistence of the ''Gunnera'' [[crown group]] since the Cretaceous makes it unique among flowering plants, and may have been facilitated by strong [[Phylogenetic niche conservatism|niche conservatism]], [[Seed dispersal|dispersal]] ability, and being able to aggressively colonize disturbed land.<ref name=":0" />