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Chlorophyta

From Wikipedia, the free encyclopedia
This article is about a group of green algae. For the genus with the common name 'spider plant', see Chlorophytum.

Chlorophyta
Temporal range: 1000–0 Ma[1]
"Siphoneae" from Ernst Haeckel's Kunstformen der Natur, 1904
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Diaphoretickes
(unranked): Archaeplastida
(unranked): Viridiplantae
Division: Chlorophyta
Reichenbach, 1828, emend. Pascher, 1914, emend. Lewis & McCourt, 2004[2][3][4]
Classes[5]
Diversity
7,934 species
(6,851 extant, 1,083 fossil)[5]
Synonyms
  • Chlorophycophyta Papenfuss 1946[6]
  • Chlorophycota
  • Chlorophytina
  • Chlorophyllophyceae
  • Isokontae
  • Stephanokontae
Green algae on coastal rocks at Shihtiping in Taiwan

Chlorophyta is a taxon of green algae informally called chlorophytes.[7]

Systematics

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Taxonomic history

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The first mention of Chlorophyta belongs to German botanist Heinrich Gottlieb Ludwig Reichenbach in his 1828 work Conspectus regni vegetabilis. Under this name, he grouped all algae, mosses ('musci') and ferns ('filices'), as well as some seed plants (Zamia and Cycas).[8] This usage did not gain popularity. In 1914, Bohemian botanist Adolf Pascher modified the name to encompass exclusively green algae, that is, algae which contain chlorophylls a and b and store starch in their chloroplasts.[9] Pascher established a scheme where Chlorophyta was composed of two groups: Chlorophyceae, which included algae now known as Chlorophyta, and Conjugatae, which are now known as Zygnematales and belong to the Streptophyta clade from which land plants evolved.[3][10]

During the 20th century, many different classification schemes for the Chlorophyta arose. The Smith system, published in 1938 by American botanist Gilbert Morgan Smith, distinguished two classes: Chlorophyceae, which contained all green algae (unicellular and multicellular) that did not grow through an apical cell; and Charophyceae, which contained only multicellular green algae that grew via an apical cell and had special sterile envelopes to protect the sex organs.[11]

With the advent of electron microscopy studies, botanists published various classification proposals based on finer cellular structures and phenomena, such as mitosis, cytokinesis, cytoskeleton, flagella and cell wall polysaccharides.[12][13] British botanist Frank Eric Round [nl] proposed in 1971 a scheme which distinguishes Chlorophyta from other green algal divisions Charophyta, Prasinophyta and Euglenophyta. He included four classes of chlorophytes: Zygnemaphyceae, Oedogoniophyceae, Chlorophyceae and Bryopsidophyceae.[14] Other proposals retained the Chlorophyta as containing all green algae, and varied from one another in the number of classes. For example, the 1984 proposal by Mattox & Stewart included five classes,[12] while the 1985 proposal by Bold & Wynne included only two,[15] and the 1995 proposal by Christiaan van den Hoek and coauthors included up to eleven classes.[9]

Modern classification

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The modern usage of the name 'Chlorophyta' was established in 2004, when phycologists Lewis & McCourt firmly separated the chlorophytes from the streptophytes on the basis of molecular phylogenetics. All green algae that were more closely related to land plants than to chlorophytes were grouped as a paraphyletic division Charophyta.[10]

Within the green algae, the most basal lineages were grouped under the informal name of "prasinophytes", and they were all believed to belong to the Chlorophyta clade.[10] However, in 2020 a study recovered a new clade and division known as Prasinodermophyta, which contains two prasinophyte lineages previously considered chlorophytes.[16] Below is a cladogram representing the current state of green algal classification:[17][16][18][19]

Viridiplantae

Ecology

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Most species of Chlorophyta are aquatic, prevalent in both marine and freshwater environments. About 90% of all known species live in freshwater.[20] However, some species have adapted to a wide range of terrestrial environments. For example, Chlamydomonas nivalis lives on summer alpine snowfields, and Trentepohlia species, live attached to rocks or woody parts of trees.[21][22] Several species have adapted to specialised and extreme environments, such as deserts, arctic environments, hypersaline habitats, marine deep waters, deep-sea hydrothermal vents and habitats that experiences extreme changes in temperature, light and salinity.[23][24][25][26] Some groups, such as the Trentepohliales are exclusively found on land.[27] Several species of Chlorophyta live in symbiosis with a diverse range of eukaryotes, including fungi (to form lichens), ciliates, forams, cnidarians and molluscs.[22] Some species of Chlorophyta are heterotrophic, either free-living or parasitic.[28][29] Others are mixotrophic bacterivores through phagocytosis.[30] Two common species of the heterotrophic green alga Prototheca are pathogenic and can cause the disease protothecosis in humans and animals.[31]

With the exception of the three classes Ulvophyceae, Trebouxiophyceae and Chlorophyceae in the UTC clade, which show various degrees of multicellularity, all the Chlorophyta lineages are unicellular.[32] Some members of the group form symbiotic relationships with protozoa, sponges, and cnidarians. Others form symbiotic relationships with fungi to form lichens, but the majority of species are free-living. Some conduct sexual reproduction, which is oogamous or isogamous. All members of the clade have motile flagellated swimming cells.[33] Monostroma kuroshiense, an edible green alga cultivated worldwide and most expensive among green algae, belongs to this group.

Fossil record

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In February 2020, the fossilized remains of green algae, named Proterocladus antiquus were discovered in the northern province of Liaoning, China. At around a billion years old (1,000 Ma), it is believed to be one of the oldest examples of a multicellular chlorophyte.[1]

References

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Citations

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  1. ^ a b Tang et al. 2020.
  2. ^ Reichenbach 1828, p. 23.
  3. ^ a b Pascher 1914.
  4. ^ Adl et al. 2019, p. 36.
  5. ^ a b Guiry 2024.
  6. ^ Papenfuss 1955.
  7. ^ Rockwell et al. 2017.
  8. ^ Reichenbach 1828, p. 23–40.
  9. ^ a b van den Hoek, Mann & Jahns 1995.
  10. ^ a b c Lewis & McCourt 2004.
  11. ^ Smith 1938, p. 12.
  12. ^ a b Mattox & Stewart 1984.
  13. ^ Lobban & Wynne 1981, p. 88.
  14. ^ Round 1971.
  15. ^ Bold & Wynne 1985.
  16. ^ a b Li et al. 2020.
  17. ^ Lopes dos Santos et al. 2017.
  18. ^ Gulbrandsen et al. 2021.
  19. ^ Yang et al. 2023.
  20. ^ Lee 2018.
  21. ^ Graham et al. 2022.
  22. ^ a b Leliaert et al. 2012.
  23. ^ Lewis & Lewis 2005.
  24. ^ De Wever et al. 2009.
  25. ^ Leliaert, Verbruggen & Zechman 2011.
  26. ^ Foflonker et al. 2016.
  27. ^ López-Bautista, Rindi & Guiry 2006.
  28. ^ Joubert & Rijkenberg 1971.
  29. ^ Nedelcu 2001.
  30. ^ Anderson, Charvet & Hansen 2018.
  31. ^ Tartar et al. 2002.
  32. ^ Umen 2014.
  33. ^ Kapraun 2007.

Cited literature

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Further reading

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Wikispecies has information related to Chlorophyta.
Wikimedia Commons has media related to Chlorophyta.
  • Burrows EM (1991). Seaweeds of the British Isles. Vol. 2 (Chlorophyta). London: Natural History Museum. ISBN 978-0-565-00981-6.
  • Pickett-Heaps JD (1975). Green Algae. Structure, Reproduction and Evolution in Selected Genera. Stamford, CT: Sinauer Assoc. p. 606.
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