Choanoflagellate

"Choanoflagellates" redirects here. For the clade that groups these organisms with animals, see Choanozoa.

Choanoflagellates
Temporal range: Neoproterozoic-present, fossils from 100.5–0 Ma Only possible fossils are known from Cretaceous (Cenomanian/Turonian)[1][2]
Codosiga sp.
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Amorphea
Clade: Obazoa
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Clade: Choanozoa
Class: Choanoflagellata
Kent, 1880–1882[3][4]
Type species
Monosiga brevicollis[5]
Orders & families
Synonyms
  • Craspedmonadina Stein, 1878
  • Craspedomonadaceae Senn, 1900
  • Craspedophyceae Chadefaud, 1960
  • Craspédomonadophycidées Bourrelly, 1968
  • Craspedomonadophyceae Hibberd, 1976
  • Choanomonadea Krylov et al., 1980
  • Choanoflagellida Levine et al., 1980, Lee et al., 1985
  • Choanoflagellea Cavalier-Smith, 1997
  • Choanomonada Adl et al. 2005[6]
  • Choanoflagellatea Cavalier-Smith, 1998[7][8]

The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals. Choanoflagellates are collared flagellates, having a funnel shaped collar of interconnected microvilli at the base of a flagellum. Choanoflagellates are capable of both asexual and sexual reproduction.[9] They have a distinctive cell morphology characterized by an ovoid or spherical cell body 3–10 μm in diameter with a single apical flagellum surrounded by a collar of 30–40 microvilli (see figure). Movement of the flagellum creates water currents that can propel free-swimming choanoflagellates through the water column and trap bacteria and detritus against the collar of microvilli, where these foodstuffs are engulfed. This feeding provides a critical link within the global carbon cycle, linking trophic levels. In addition to their critical ecological roles, choanoflagellates are of particular interest to evolutionary biologists studying the origins of multicellularity in animals. As the closest living relatives of animals, choanoflagellates serve as a useful model for reconstructions of the last unicellular ancestor of animals. According to a 2021 study, crown group craspedids (and perhaps crown group choanoflagellates if Acanthoecida arose within Craspedida[10]) appeared 422.78 million years ago,[11] Although a previous study from 2017 recovered the divergence of the crown group choanoflagellates (craspedids) at 786.62 million years.[12]

  1. ^ Fonseca, Carolina; Mendonça Filho, João Graciano; Reolid, Matías; Duarte, Luís V.; de Oliveira, António Donizeti; Souza, Jaqueline Torres; Lézin, Carine (2023-01-23). "First putative occurrence in the fossil record of choanoflagellates, the sister group of Metazoa". Scientific Reports. 13 (1): 1242. Bibcode:2023NatSR..13.1242F. doi:10.1038/s41598-022-26972-8. ISSN 2045-2322. PMC 9870899. PMID 36690681.
  2. ^ Parfrey LW, Lahr DJ, Knoll AH, Katz LA (August 2011). "Estimating the timing of early eukaryotic diversification with multigene molecular clocks". Proceedings of the National Academy of Sciences of the United States of America. 108 (33): 13624–9. Bibcode:2011PNAS..10813624P. doi:10.1073/pnas.1110633108. PMC 3158185. PMID 21810989.
  3. ^ Saville-Kent, W. (1880). A manual of Infusoria. London, vol. 1, p. 324, [1].
  4. ^ Adl SM, Bass D, Lane CE, Lukeš J, Schoch CL, Smirnov A, Agatha S, Berney C, Brown MW, Burki F, Cárdenas P, Čepička I, Chistyakova L, del Campo J, Dunthorn M, Edvardsen B, Eglit Y, Guillou L, Hampl V, Heiss AA, Hoppenrath M, James TY, Karnkowska A, Karpov S, Kim E, Kolisko M, Kudryavtsev A, Lahr DJG, Lara E, Le Gall L, Lynn DH, Mann DG, Massana R, Mitchell EAD, Morrow C, Park JS, Pawlowski JW, Powell MJ, Richter DJ, Rueckert S, Shadwick L, Shimano S, Spiegel FW, Torruella G, Youssef N, Zlatogursky V, Zhang Q (2019). "Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes". Journal of Eukaryotic Microbiology. 66 (1): 4–119. doi:10.1111/jeu.12691. PMC 6492006. PMID 30257078.
  5. ^ King N, Westbrook MJ, Young SL, Kuo A, Abedin M, Chapman J, et al. (February 2008). "The genome of the choanoflagellate Monosiga brevicollis and the origin of metazoans". Nature. 451 (7180): 783–8. Bibcode:2008Natur.451..783K. doi:10.1038/nature06617. PMC 2562698. PMID 18273011.
  6. ^ Nitsche F, Carr M, Arndt H, Leadbeater BS (2011). "Higher level taxonomy and molecular phylogenetics of the Choanoflagellatea". The Journal of Eukaryotic Microbiology. 58 (5): 452–62. doi:10.1111/j.1550-7408.2011.00572.x. PMID 21895836. S2CID 2076733.
  7. ^ Cavalier-Smith T (1998). "Neomonada and the origin of animals and fungi.". In Coombs GH, Vickerman K, Sleigh MA, Warren A (eds.). Evolutionary relationships among protozoa. London: Kluwer. pp. 375–407.
  8. ^ Leadbeater BS (2015). The choanoflagellates: evolution, biology, and ecology. University of Birmingham. ISBN 978-0-521-88444-0.
  9. ^ "Bacterial protein acts as aphrodisiac for choanoflagellates".
  10. ^ Carr, Martin; Leadbeater, Barry S. C. (2022-12-01). "Re-evaluating Loricate Choanoflagellate Phylogenetics: Molecular Evidence Points to the Paraphyly of Tectiform Species". Protist. 173 (6): 125924. doi:10.1016/j.protis.2022.125924. ISSN 1434-4610.
  11. ^ Schiwitza, Sabine; Gutsche, Lennart; Freches, Eric; Arndt, Hartmut; Nitsche, Frank (2021-06-01). "Extended divergence estimates and species descriptions of new craspedid choanoflagellates from the Atacama Desert, Northern Chile". European Journal of Protistology. 79: 125798. doi:10.1016/j.ejop.2021.125798. ISSN 0932-4739.
  12. ^ Dohrmann, Martin; Wörheide, Gert (2017-06-15). "Dating early animal evolution using phylogenomic data". Scientific Reports. 7 (1): 3599. doi:10.1038/s41598-017-03791-w. ISSN 2045-2322. PMC 5472626.