Lophotrochozoa
Oxford Dictionary of Genetics:
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Lophotrochozoa
a clade that contains the phyla Platyhelminthes, Annelida, and Mollusca. These animals all have quite similar nucleotide sequences in their 18S rRNA genes (q.v.), and they share a cluster of HOX genes (q.v.) quite different from the clusters found in ecdysozoans (q.v.) and deuterostomes (q.v.).
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Lophotrochozoa
| Lophotrochozoa Temporal range: Early Cambrian - Recent |
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| Caribbean Reef Squid or Sepioteuthis sepioidea is a complex lophotrochozoan. | |
| Scientific classification | |
| Kingdom: | Animalia |
| Subkingdom: | Eumetazoa |
| (unranked): | Bilateria |
| Superphylum: | Lophotrochozoa Halanych et al., 1995 |
| Phyla | |
The Lophotrochozoa (
/ləˌfɒtrɵkɵˈzoʊ.ə/, "crest/wheel animals") are a major grouping of protostome animals. The taxon was discovered based on molecular data.[1] Molecular evidence such as a result of studies of the evolution of small-subunit ribosomal RNA (rRNA) supports the monophyly of the phyla listed in the infobox shown at right.[2]
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Contents
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Terminology
The word "lophotrochozoan" is sometimes equated with spiralian.[3] When used in a broader sense (sensu lato), it can include rotifers and platyhelminthes.[4] When used sensu stricto, it refers to a subgroup of Spiralia.
Groups
The Lophotrochozoa comprise two groups, the trochozoans and the lophophorata. The exact relationships between the different phyla are not entirely certain. However, it appears that neither the lophophorates nor the trochozoa are monophyletic groups by themselves, but are mixed.[5]
- Trochozoans produce trochophore larvae, which have two bands of cilia around their middle.[5] Previously these were treated together as the Trochozoa, together with the arthropods, which do not produce trochophore larvae but were considered close relatives of the annelids because they are both segmented. However, they show a number of important differences, and the arthropods are now placed separately among the Ecdysozoa. The Trochozoa include the Nemertea, Mollusca, Sipuncula, and Annelida.[5]
- The Lophophorata are united by the presence of a lophophore, a fan of ciliated tentacles surrounding the mouth, and so were treated together as the lophophorates. They are unusual in showing radial cleavage, and some authors considered them deuterostomes, before RNA trees placed them together with the trochozoans. The Lophophorata include the Bryozoa, Entoprocta, Phoronida, and Brachiopoda.[5]
Other phyla are included on the basis of molecular data.
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See also
References
- ^ Halanych, K.M., Bacheller, J., Liva, S., Aguinaldo, A. A., Hillis, D.M. and Lake, J.A. (1995). "18S rDNA evidence that the Lophophorates are Protostome Animals". Science 267: 1641–1643. doi:10.1126/science.7886451. PMID 7886451.
- ^ Philippe, Hervé, Nicolas Lartillot1 and Henner Brinkmann. (2005) "Multigene Analyses of Bilaterian Animals Corroborate the Monophyly of Ecdysozoa, Lophotrochozoa, and Protostomia." Molecular Biology and Evolution 2005 22(5):1246–1253; doi:10.1093/molbev/msi111.
- ^ Giribet G (April 2008). "Assembling the lophotrochozoan (=spiralian) tree of life". Philos. Trans. R. Soc. Lond., B, Biol. Sci. 363 (1496): 1513–22. doi:10.1098/rstb.2007.2241. . PMID 18192183. http://rstb.royalsocietypublishing.org/cgi/pmidlookup?view=long&pmid=18192183.
- ^ "Explanations.html". http://science.kennesaw.edu/~jdirnber/InvertZoo/Tree/Explanations.html. Retrieved 2009-06-28.
- ^ a b c d Introduction to the Lophotrochozoa - accessed 8 August 2008
- ^ Jordi Paps, Jaume Baguña & Mart Riutort (July 2009). "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. doi:10.1093/molbev/msp150. PMID 19602542. http://mbe.oxfordjournals.org.oca.ucsc.edu/content/26/10/2397.abstract.
- ^ Struck, T.H.; Schult, N., Kusen, T., Hickman, E., Bleidorn. C., McHugh, D., and Halanych, K.M. (2007). "Annelid phylogeny and the status of Sipuncula and Echiura". BMC Evolutionary Biology 7: 57. doi:10.1186/1471-2148-7-57. . PMID 17411434. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1855331.
- ^ Hausdorf, B.; Helmkampf, M., Meyer, A., et al (2007). "Spiralian Phylogenomics Supports the Resurrection of Bryozoa Comprising Ectoprocta and Entoprocta". Molecular Biology and Evolution 24 (12): 2723–2729. doi:10.1093/molbev/msm214. PMID 17921486.
Further reading
- Podsiadlowski R. 2009. Phylogeny and mitochondrial gene order variation in Lophotrochozoa in the light of new mitogenomic data from Nemertea. BMC Genomics 2009, 10:364. doi:10.1186/1471-2164-10-364
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