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Sequoioideae

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"Redwood" redirects here. For other uses, seeRedwood (disambiguation)."Redwood Tree" redirects here. For the song, seeRedwood Tree (song).

Sequoioideae
Temporal range:Aalenian–Present
Redwood Highway, CaliforniaSequoia sempervirens
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Gymnospermae
Division: Pinophyta
Class: Pinopsida
Order: Cupressales
Family: Cupressaceae
Subfamily: Sequoioideae
Genera

Sequoioideae,commonly referred to asredwoods,is asubfamilyofconiferoustrees within thefamilyCupressaceae,that range in thenorthern hemisphere.It includes thelargest and tallest treesin the world. The trees in thesubfamilyare amongst the most notable trees in the world and are commonornamentaltrees. Thesubfamilyreached its peak diversity in the earlycenozoic.

Description

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The three redwood subfamilygeneraareSequoiafrom coastalCaliforniaandOregon,Sequoiadendronfrom California'sSierra Nevada,andMetasequoiainChina.The redwood species contains the largest and tallest trees in the world. These trees can live for thousands of years. Threats include logging, fire suppression,[1]illegal marijuana cultivation, andburlpoaching.[2][3]

Only two of the genera,SequoiaandSequoiadendron,are known for massive trees. Trees ofMetasequoia,from the single living speciesMetasequoia glyptostroboides,are deciduous, grow much smaller (although are still large compared to most other trees) and can live in colder climates.[citation needed]

Taxonomy and evolution

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Multiple studies of both morphological and molecular characters have strongly supported the assertion that the Sequoioideae aremonophyletic.[4][5][6][7]Most modernphylogeniesplaceSequoiaas sister toSequoiadendronandMetasequoiaas the out-group.[5][7][8]However, Yanget al.went on to investigate the origin of a peculiar genetic component in Sequoioideae, thepolyploidyofSequoia—and generated a notable exception that calls into question the specifics of this relative consensus.[7]

Cladistic tree

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A 2006 paper based on non-molecular evidence suggested the following relationship among extant species:[9]

Sequoioideae

Taxodioideae

A 2021 study using molecular evidence found the same relationships among Sequoioideae species, but found Sequoioideae to be the sister group to theAthrotaxidoideae(a superfamily presently known only fromTasmania) rather than toTaxodioideae.Sequoioideae and Athrotaxidoideae are thought to have diverged from each other during theJurassic.[10]

Possible reticulate evolution in Sequoioideae

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Reticulate evolutionrefers to the origination of a taxon through the merging of ancestor lineages. Polyploidyhas come to be understood as quite common in plants—with estimates ranging from 47% to 100% of flowering plants and extantfernshaving derived from ancient polyploidy.[11]Within the gymnosperms however it is quite rare.Sequoia sempervirensishexaploid(2n= 6x= 66). To investigate the origins of this polyploidy Yang et al. used two single copynuclear genes,LFYand NLY, to generatephylogenetic trees.Other researchers have had success with these genes in similar studies on different taxa.[7]

Several hypotheses have been proposed to explain the origin ofSequoia'spolyploidy:allopolyploidybyhybridizationbetweenMetasequoiaand some probably extincttaxodiaceousplant;MetasequoiaandSequoiadendron,or ancestors of the two genera, as the parental species ofSequoia;andautohexaploidy,autoallohexaploidy, or segmental allohexaploidy.[citation needed]

Yang et al. found thatSequoiawas clustered withMetasequoiain the tree generated using the LFY gene but withSequoiadendronin the tree generated with the NLY gene. Further analysis strongly supported the hypothesis thatSequoiawas the result of ahybridization eventinvolvingMetasequoiaandSequoiadendron.Thus, Yang et al. hypothesize that the inconsistent relationships amongMetasequoia,Sequoia,andSequoiadendroncould be a sign ofreticulate evolutionbyhybrid speciation(in which two species hybridize and give rise to a third) among the three genera. However, the long evolutionary history of the three genera (the earliest fossil remains being from theJurassic) make resolving the specifics of when and howSequoiaoriginated once and for all a difficult matter—especially since it in part depends on an incomplete fossil record.[8]

Extant species

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Paleontology

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Sequoioideae is an ancienttaxon,with the oldest described Sequoioideae species,Sequoia jeholensis,recovered fromJurassicdeposits.[12][13]The fossil woodMedulloprotaxodioxylon,reported from the late Triassic of China, resemblesSequoiadendron giganteumand may represent an ancestral form of the Sequoioideae; this supports the idea of a Late TriassicNorianorigin for this subfamily.[14]

The fossil record shows a massive expansion of range in theCretaceousand dominance of theArcto-Tertiary Geoflora,especially in northern latitudes. Genera of Sequoioideae were found in theArctic Circle,Europe, North America, and throughout Asia and Japan.[15]A general cooling trend beginning in the lateEoceneandOligocenereduced the northern ranges of the Sequoioideae, as did subsequent ice ages.[16]Evolutionary adaptations to ancient environments persist in all three species despite changing climate, distribution, and associated flora, especially the specific demands of their reproduction ecology that ultimately forced each of the species into refugial ranges where they could survive.[citation needed]

The extinct genusAustrosequoia,known from the Late Cretaceous-Oligocene of the Southern Hemisphere, including Australia and New Zealand, has been suggested as a member of the subfamily.[17]

Young but already tall redwood trees (Sequoia sempervirens) in Oakland, California

Conservation

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In 2024, it was estimated that there were about 500,000 redwoods in Britain, mostly brought as seeds and seedlings from the US in theVictorian era.[18]The entire subfamily isendangered.TheIUCN Red ListCategory & Criteria assessesSequoia sempervirensas Endangered (A2acd),Sequoiadendron giganteumas Endangered (B2ab) andMetasequoia glyptostroboidesas Endangered (B1ab). In 2024 it was reported that over a period of two years about one-fifth of all giant sequoias were destroyed in extreme wildfires in California.[19]

See also

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  • Temperatecloud forestof North American west coast (Sequoia forests)

References

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  1. ^"Prescribed Fire at Redwood National and State Parks - Redwood National and State Parks (U.S. National Park Service)".
  2. ^"Why redwood burl poaching is so destructive".Christian Science Monitor.5 March 2014.
  3. ^Kurland, Justin; Pires, Stephen F; Marteache, Nerea (2018). "The spatial pattern of redwood burl poaching and implications for prevention".Forest Policy and Economics.94:46–54.doi:10.1016/j.forpol.2018.06.009.S2CID158505170.
  4. ^Brunsfeld, Steven J; Soltis, Pamela S; Soltis, Douglas E; Gadek, Paul A; Quinn, Christopher J; Strenge, Darren D; Ranker, Tom A (1994). "Phylogenetic Relationships Among the Genera of Taxodiaceae and Cupressaceae: Evidence from rbcL Sequences".Systematic Botany.19(2): 253.doi:10.2307/2419600.JSTOR2419600.
  5. ^abGadek, P.A.; Alpers, D.L.; Heslewod, M.M.; Quinn, C.J. (2000)."Relationships Within Cupressaceae Sensu Lato: A Combined Morphological and Molecular Approach".American Journal of Botany.87(7): 1044–57.doi:10.2307/2657004.JSTOR2657004.PMID10898782.
  6. ^Takaso, T.; Tomlinson, P.B. (1992). "Seed cone and ovule ontogeny in Metasequoia, Sequoia and Sequoiadendron (Taxodiaceae-Coniferales)".Botanical Journal of the Linnean Society.109:15–37.doi:10.1111/j.1095-8339.1992.tb00256.x.
  7. ^abcdYang, Z.Y.; Ran, J.H.; Wang, X.Q. (2012). "Three Genome-based Phylogeny of Cupressaceae s.l: Further Evidence for the Evolution of Gymnosperms and Southern Hemisphere Biogeography".Molecular Phylogenetics and Evolution.64(3): 452–470.doi:10.1016/j.ympev.2012.05.004.PMID22609823.
  8. ^abMao, K.; Milne, R.I.; Zhang, L.; Peng, Y.; Liu, J.; Thomas, P.; Mill, R.R.; Renner, S.S. (2012)."Distribution of Living Cupressaceae Reflects the Breakup of Pangea".Proceedings of the National Academy of Sciences.109(20): 7793–7798.Bibcode:2012PNAS..109.7793M.doi:10.1073/pnas.1114319109.PMC3356613.PMID22550176.
  9. ^Schulz; Stützel (August 2007)."Evolution of taxodiaceous Cupressaceae (Coniferopsida)".Organisms Diversity & Evolution.7(2): 124–135.doi:10.1016/j.ode.2006.03.001.
  10. ^Stull, Gregory W.; Qu, Xiao-Jian; Parins-Fukuchi, Caroline; Yang, Ying-Ying; Yang, Jun-Bo; Yang, Zhi-Yun; Hu, Yi; Ma, Hong; Soltis, Pamela S.; Soltis, Douglas E.; Li, De-Zhu (August 2021)."Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms".Nature Plants.7(8): 1015–1025.doi:10.1038/s41477-021-00964-4.ISSN2055-0278.PMID34282286.S2CID236141481.
  11. ^Soltis, D.E.;Buggs, R.J.A.; Doyle, J.J.;Soltis, P.S.(2010)."What we still don't know about polyploidy".Taxon.59(5): 1387–1403.doi:10.1002/tax.595006.JSTOR20774036.
  12. ^Ma, Qing-Wen; K. Ferguson, David; Liu, Hai-Ming; Xu, Jing-Xian (2020)."Compressions of Sequoia (Cupressaceae sensu lato) from the Middle Jurassic of Daohugou, Ningcheng, Inner Mongolia, China".Palaeobiodiversity and Palaeoenvironments.1(9): 1.doi:10.1007/s12549-020-00454-z.S2CID227180592.Retrieved9 March2021.
  13. ^Ahuja M. R. and D. B. Neale. 2002.Origins of polyploidy in coast redwood (Sequoia sempervirens) and relationship of coast redwood (Sequoia sempervirens) to other genera of Taxodiaceae.Archived2 January 2014 at theWayback MachineSilvae Genetica 51: 93–99.
  14. ^Wan, Mingli; Yang, Wan; Tang, Peng; Liu, Lujun; Wang, Jun (2017). "Medulloprotaxodioxylon triassicum gen. Et sp. Nov., a taxodiaceous conifer wood from the Norian (Triassic) of northern Bogda Mountains, northwestern China".Review of Palaeobotany and Palynology.241:70–84.doi:10.1016/j.revpalbo.2017.02.009.
  15. ^Chaney, Ralph W. (1950)."Revision of Fossil Sequoia and Taxodium in Western North America Based on the Recent Discovery of Metasequoia".Transactions of the American Philosophical Society.40(3). Philadelphia: 172–236.doi:10.2307/1005641.ISBN978-1422377055.JSTOR1005641.Retrieved1 January2014.
  16. ^Jagels, Richard; Equiza, María A. (2007). "Why did Metasequoia disappear from North America but not from China?".Bulletin of the Peabody Museum of Natural History.48(2): 281–290.doi:10.3374/0079-032x(2007)48[281:wdmdfn]2.0.co;2.S2CID129649877.
  17. ^Mays, Chris; Cantrill, David J.; Stilwell, Jeffrey D.; Bevitt, Joseph J. (28 May 2018)."Neutron tomography of Austrosequoia novae-zeelandia e comb. nov. (Late Cretaceous, Chatham Islands, New Zealand): implications for Sequoioideae phylogeny and biogeography".Journal of Systematic Palaeontology.16(7): 551–570.doi:10.1080/14772019.2017.1314898.ISSN1477-2019.
  18. ^Tapper, James (16 March 2024)."Hidden giants: how the UK's 500,000 redwoods put California in the shade".The Guardian.
  19. ^Sommer, Lauren; Kellman, Ryan (26 February 2024)."Wildfires are killing California's ancient giants. Can seedlings save sequoia trees?".NPR.Retrieved16 March2024.
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