Lophotrochozoa Explained

Lophotrochozoa ("crest/wheel animals") is a clade of protostome animals within the Spiralia. The taxon was established as a monophyletic group based on molecular evidence.[1] [2] The clade includes animals like annelids, molluscs, bryozoans, and brachiopods.

Groups

See also: List of bilaterial animal orders.

Lophotrochozoa was defined in 1995 as the "last common ancestor of the three traditional lophophorate taxa (brachiopods, bryozoans, and phoronid worms), the mollusks and the annelids, and all of the descendants of that common ancestor".[3] It is a cladistic definition (a node-based name), so the affiliation to Lophotrochozoa of spiralian groups not mentioned directly in the definition depends on the topology of the spiralian tree of life, and in some phylogenetic hypotheses, Lophotrochozoa may even be synonymous to Spiralia. Nemertea and Orthonectida (if not directly considered as part of Annelida) are probably lophotrochozoan phyla; Dicyemida, Gastrotricha, and Platyhelminthes may be lophotrochozoans or placed in the Rouphozoa clade outside Lophotrochozoa; Chaetognatha, Gnathostomulida, Micrognathozoa, and Syndermata are probably gnathiferans and so placed as a basal spiralian clade outside Lophotrochozoa; Cycliophora could be a gnathiferan or a lophotrochozoan phylum. One of the candidate hypotheses is presented below.

The Lophotrochozoa has basal Cycliophora and Mollusca groups, and more derived Lophophorate, Nemertea and Annelida groups.[4] [5]

With the introduction of Platytrochozoa and Rouphozoa, one candidate phylogeny is pictured below – though other studies recover a range of alternative possibilities:[6] [7] [8] [9] [10] [11] [12] [13]

In the most recent research, the three phyla Cycliophora, Entoprocta and Bryozoa makes up a single clade and are the first to branch off from the other lophotrochozoans. The second split is the molluscs, and the third consists of two sister phyla, annelids and nemerteans. Lastly remains the clade that consist of the phoronids and the brachiopods.[14] [15]

Another study recovers Lophotrochozoa as equivalent to Platytrochozoa, forming a sister group with Gnathifera at the base of Spiralia.[16]

A number of fossil taxa can be identified as early Lophotrochozoans, even if their precise affinity remains contested. However, relevant Cambrian fossils are debated.

Characteristics

The clade Lophotrochozoa is named after the two distinct characteristics of its members; the lophophore, a feeding structure consisting of a ciliated crown of tentacles surrounding a mouth, and the developmental stage of the trochophore larva. Lophophorata such as Brachiozoa and Bryozoa have lophophores, while members of Trochozoa such as molluscs and annelids have trochophore larvae, although some may have none.[17] [18]

Further reading

Notes and References

  1. Halanych . K. M. . Bacheller . J. . Liva . S. . Aguinaldo . A. A. . Hillis . D. M. . Lake . J. A. . 17 March 1995 . 18S rDNA evidence that the Lophophorates are Protostome Animals . Science . 267 . 5204 . 1641–1643 . 10.1126/science.7886451 . 7886451 . 12196991.
  2. Hervé . Philippe . Lartillot . Nicolas . Brinkmann . Henner . May 2005 . Multigene Analyses of Bilaterian Animals Corroborate the Monophyly of Ecdysozoa, Lophotrochozoa, and Protostomia . Molecular Biology and Evolution . 22 . 5. 1246–1253 . 10.1093/molbev/msi111 . 15703236. free .
  3. Halanych . Kenneth M. . Bacheller . John D. . Aguinaldo . Anna Marie A. . Liva . Stephanie M. . Hillis . David M. . Lake . James A. . Evidence from 18S ribosomal DNA that the lophophorates are protostome animals . Science . 1995-03-17 . 267 . 5204 . 1642 . 10.1126/science.7886451 . 7886451 . 2021-02-16 . American Association for the Advancement of Science . 1995Sci...267.1641H . 12196991 . 1095-9203.
  4. Nesnidal . Maximilian P . Helmkampf . Martin . Meyer . Achim . Witek . Alexander . Bruchhaus . Iris . Ebersberger . Ingo . Hankeln . Thomas . Lieb . Bernhard . Struck . Torsten H . Hausdorf . Bernhard . New phylogenomic data support the monophyly of Lophophorata and an Ectoproct-Phoronid clade and indicate that Polyzoa and Kryptrochozoa are caused by systematic bias . BMC Evolutionary Biology . 2013 . 13 . 1 . 253 . 10.1186/1471-2148-13-253 . 24238092 . 4225663 . free . 2013BMCEE..13..253N .
  5. Laumer . Christopher E. . Bekkouche . Nicolas . Kerbl . Alexandra . Goetz . Freya . Neves . Ricardo C. . Sørensen . Martin V. . Kristensen . Reinhardt M. . Hejnol . Andreas . Dunn . Casey W. . Giribet . Gonzalo . Worsaae . Katrine . Spiralian Phylogeny Informs the Evolution of Microscopic Lineages . Current Biology . August 2015 . 25 . 15 . 2000–2006 . 10.1016/j.cub.2015.06.068 . 26212884 . free. 2015CBio...25.2000L .
  6. Paps . Jordi . Baguñà . Jaum . Riutort . Marta . 2009-10-01 . Bilaterian Phylogeny: A Broad Sampling of 13 Nuclear Genes Provides a New Lophotrochozoa Phylogeny and Supports a Paraphyletic Basal Acoelomorpha . Molecular Biology and Evolution . 26 . 10 . 2397–2406 . 10.1093/molbev/msp150 . 19602542 . free .
  7. Struck . Torsten H. . Schult . Nancy . Kusen . Tiffany . Hickman . Emily . Bleidorn . Christoph . McHugh . Damhnait . Halanych . Kenneth M . Annelid phylogeny and the status of Sipuncula and Echiura . BMC Evolutionary Biology . 5 April 2007 . 7 . 1 . 57 . 10.1186/1471-2148-7-57 . 17411434 . 1855331 . free . 2007BMCEE...7...57S .
  8. Hausdorf . Bernhard . Helmkampf . Martin . Meyer . Achim . Witek . Alexander . Herlyn . Holger . Bruchhaus . Iris . Hankeln . Thomas . Struck . Torsten H. . Lieb . Bernhard . 2007-12-01 . Spiralian Phylogenomics Supports the Resurrection of Bryozoa Comprising Ectoprocta and Entoprocta . Molecular Biology and Evolution . 24 . 12 . 2723–2729 . 10.1093/molbev/msm214 . 17921486 . free .
  9. Struck . Torsten H. . Wey-Fabrizius . Alexandra R. . Golombek . Anja . Hering . Lars . Weigert . Anne . Bleidorn . Christoph . Klebow . Sabrina . Iakovenko . Nataliia . Hausdorf . Bernhard . Petersen . Malte . Kück . Patrick . Herlyn . Holger . Hankeln . Thomas . Platyzoan Paraphyly Based on Phylogenomic Data Supports a Noncoelomate Ancestry of Spiralia . Molecular Biology and Evolution . July 2014 . 31 . 7 . 1833–1849 . 10.1093/molbev/msu143 . 24748651 . free .
  10. Web site: cycliophorans . Encyclopedia of Life .
  11. Lu . Tsai-Ming . Kanda . Miyuki . Satoh . Noriyuki . Furuya . Hidetaka . The phylogenetic position of dicyemid mesozoans offers insights into spiralian evolution . Zoological Letters . 29 May 2017 . 3 . 1 . 6 . 10.1186/s40851-017-0068-5 . 28560048 . 5447306 . free .
  12. Temereva . Elena N. . Kuzmina . Tatyana V. . The first data on the innervation of the lophophore in the rhynchonelliform brachiopod Hemithiris psittacea: what is the ground pattern of the lophophore in lophophorates? . BMC Evolutionary Biology . 31 July 2017 . 17 . 1 . 172 . 10.1186/s12862-017-1029-5 . 28760135 . 5537927 . free . 2017BMCEE..17..172T .
  13. Luo . Yi-Jyun . Kanda . Miyuki . Koyanagi . Ryo . Hisata . Kanako . Akiyama . Tadashi . Sakamoto . Hirotaka . Sakamoto . Tatsuya . Satoh . Noriyuki . Nemertean and phoronid genomes reveal lophotrochozoan evolution and the origin of bilaterian heads . Nature Ecology & Evolution . 4 December 2017 . 2 . 1 . 141–151 . 10.1038/s41559-017-0389-y . 29203924 . free . 2017NatEE...2..141L .
  14. https://www.science.org/doi/10.1126/sciadv.abo4400 Polyzoa is back: The effect of complete gene sets on the placement of Ectoprocta and Entoprocta
  15. https://www.the-scientist.com/news-opinion/phyla-of-tiny-filter-feeders-find-a-new-spot-on-the-tree-of-life-70193 Phyla of Tiny Filter Feeders Find a New Spot on the Tree of Life
  16. Rokhsar . Daniel S. . Satoh . Noriyuki . Goto . Taichiro . Peijnenburg . Katja T. C. A. . Marlétaz . Ferdinand . 2019-01-10 . A New Spiralian Phylogeny Places the Enigmatic Arrow Worms among Gnathiferans . . 29 . 2 . 312–318.e3 . 10.1016/j.cub.2018.11.042 . 30639106 . 0960-9822 . free. 2019CBio...29E.312M .
  17. Book: Barnes . Robert D. . Invertebrate Zoology . 1982 . 978-0-03-056747-6 . 1015202568 . 200–206 . Saunders College .
  18. Book: Reece . Jane B. . Urry . Lisa A. . Cain . Michael L. . 2013 . Campbell Biology . Pearson . Berkeley, California . 688 . 978-0-321-77565-8 .

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