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Thomas Cavalier-Smith

Thomas Cavalier-Smith
genome size evolution, and endosymbiosis. Though fairly well known, many of his strongest claims have been controversial and have not gained widespread acceptance in the scientific community to date. Most recently, he has published a paper citing the paraphyly of his bacterial kingdom, the origin of Neomura from Actinobacteria and taxonomy of prokaryotes. According to Palaeos.com: Prof. Cavalier-Smith of Oxford University has produced a large body of work which is well-regarded. Still, he is controversial in a way that is a bit difficult to describe. The issue may be one of writing style. Cavalier-Smith has a tendency to make pronouncements where others would use declarative sentences, to use declarative sentences where others would express an opinion, and to express opinions where angels would fear to tread. In addition, he can sound arrogant, reactionary, and even perverse. On the other [hand], he has a long history of being right when everyone else was wrong. To our way of thinking, all of this is overshadowed by one incomparable virtue: the fact that he will grapple with the details. This makes for very long, very complex papers and causes all manner of dark murmuring, tearing of hair, and gnashing of teeth among those tasked with trying to explain his views of early life. See, [for example], Zrzavý (2001) [2] [and] Patterson (1999) [3]. Nevertheless, he deals with all of the relevant facts. [4]

Professor Thomas (Tom) Cavalier-Smith (born October 21, 1942), FRS, FRSC, NERC Professorial Fellow, is a Professor of Evolutionary Biology in the Department of Zoology, at the University of Oxford. He was presented with the International Prize for Biology (a prize of 10 million yen) in 2004 [1]. Cavalier-Smith has published extensively on the classification of protists. One of his major contributions to biology was his proposal of a new kingdom of life: the Chromista, although the usefulness of the grouping is still open to debate. He also proposed that all chromista and alveolata share the same common ancestor, a claim later supported by studies of morphological and molecular evidence by other labs. He named this new group the Chromalveolates. He also proposed and named many other high-rank taxa, like Opisthokonta (1987), Rhizaria (2002), and Excavata (2002). Together with Chromalveolata, Amoebozoa (he emended their description in 1998), and Archaeplastida (which he called Plantae since 1981) the six form the basis of current taxonomy of eukaryotes. Prof. Cavalier-Smith has also published prodigiously on issues such as the origin of various cellular organelles (including the nucleus, mitochondria),

Cavalier-Smith’s eight kingdom model
In 1993, Cavalier-Smith divided the living world into eight kingdoms: Plantae, Animalia, Protozoa, Fungi, Eubacteria, Archaebacteria, Chromista, and Archezoa. [5] Later he abandoned the kingdoms Archaebacteria and Archezoa in favor of a six kingdom model. [6] His older eight kingdom model will be described first.

The first two kingdoms of life: plants and animals
The use of the word "kingdom" to describe the living world dates as far back as Linnaeus (1707 – 1778) who

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From Wikipedia, the free encyclopedia

Thomas Cavalier-Smith

Carl Linnaeus was a distinguished member of the animal kingdom. divided the natural world into three kingdoms: animal, vegetable, and mineral. [7] [8] The classifications "animal kingdom" (or kingdom Animalia) and "plant kingdom" (or kingdom Plantae) remain in use by modern evolutionary biologists. By 1910 the animal kingdom had been subdivided into twelve phyla: • protozoa, • porifera, • coelenterata, • platyhelminthes, • nemathelminthes, • trochhelminthes (Rotifers and Gastrotricha), • molluscoida, • echinodermata, • annulata (Polyzoa, Phoronida, and Brachiopoda), • arthropoda, • mollusca, and • chordata. The protozoa were originally classified as members of the animal kingdom. [9] Now they are classified as a separate group. Zoology is the study of animals while botany is the study of plants. While zoologists divided the animal kingdom into phyla, botanists carved the plant kingdom into "divisions". By 1940, botanists had carved the plant kingdom into five divisions: • Thallophyta (Algae, Fungi, Bacteria, and Lichenes), • Charophyta,

Redwood trees are distinguished members of the vegetable kingdom. • Bryophyta (Heptacae and Musci), • Pteridophyta, and • Spermatophyta. Fungi and bacteria were included within the plant division thallophyta. [9] Today, bacteria are no longer classified as plants and fungi are known to be more closely related to animals than to plants.

The third kingdom: protists

The sea anemone is an animal that resembles a plant.

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From Wikipedia, the free encyclopedia
By mid-nineteenth century, microscopic organisms were generally classified into four groups: • Protozoa (primitive animals), • Protophyta (primitive plants), • Phytozoa (animal-like plants & plant-like animals), and • Bacteria (primarily regarded as plants). [8] In 1858, Richard Owen (1804–1892) proposed that the animal phylum Protozoa be elevated to the status of kingdom. [5] In 1860, John Hogg (1800–1869) proposed that protozoa and protophyta be grouped together into a new kingdom which he called "Primigenum". According to Hogg, this new classification scheme prevented "the unnecessary trouble of contending about their supposed natures, and of uselessly trying to distinguish the Protozoa from the Protophyta". In 1866, Ernst Haeckel (1834–1919) proposed the name "Protista" for the Primigenum kingdom and included bacteria in this third kingdom of life. [8]

Thomas Cavalier-Smith
status of kingdom. His new classification system divided the living world into five kingdoms: • plants, • animals, • protists (excluding bacteria), • fungi, and • Monera (the kingdom bacteria). [11] Note: the word "protist" is ambiguous. Eunucleata = single celled eukaryotes Before 1959: protist = prokaryotes + Eunucleata + sponges From 1959 to 1969: protist = prokaryotes + Eunucleata Since 1969: protist = Eunucleata

The fourth kingdom: fungi

The three domains of life

Asian mushrooms, clockwise from left, enokitake, bunashimeji, bunapi-shimeji, king oyster mushroom and shiitake. Fungi are more closely related to animals than to plants. By 1959, Robert Harding Whittaker (1920–1980) proposed that fungi, which were formerly classified as plants, be given their own kingdom. His four kingdoms of life were: • the Protista, (or unicellular organisms); • the Plantae, (or multicellular plants); • the Fungi; and • the Animalia (or multicellular animals). Whittaker subdivided the Protista into two subkingdoms: • Monera (bacteria) and • Eunucleata (single celled eukaryotes). [10]

Phylogenetic tree based on Woese et al. rRNA analysis [12]

The kingdom Monera can be divided into two distinct groups: eubacteria and archaebacteria. In 1977 Carl Woese and George E. Fox proposed that eubacteria and archaebacteria both be elevated to the status of superkingdom. [13] In 1990, Woese further elevated the status of bacteria by dividing life into three domains: • eubacteria (which he called "Bacteria"), • archaebacteria (which he called "Archaea"), and • eukaryotes (which he called "Eukaryota"). [12]

eukaryotes = plants + chromista + animals + fungi + Eunucleata prokaryotes = Monera = eubacteria + archaebacteria Note: the modern use of the word "bacteria" is ambiguous. It may refer either to eubacteria (as in the above

The fifth kingdom: bacteria
Bacteria are fundamentally different from the eukaryotes (plants, animals, fungi, amebas, protozoa, and chromista). Eukaryotes have cell nuclei, bacteria do not. In 1969, Robert Whittaker elevated the bacteria to the

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From Wikipedia, the free encyclopedia
phylogenetic tree) or prokaryotes (as in reference to the kingdom Monera).

Thomas Cavalier-Smith

The eighth kingdom: archezoa
Cavalier-Smith’s eighth kingdom, Archezoa [15] is now defunct. He now assigns former members of the kingdom Archezoa to the phylum Amoebozoa. [16]

The seventh kingdom: chromista

Kingdom protozoa
Cavalier-Smith referred to what remained of the protist kingdom, after he removed the kingdoms Archezoa and Chromista, as the "kingdom Protozoa". In 1993, this kingdom contained 18 phyla as summarized in the following table: [5] # 1 2 Phylum Percolozoa Parabasalia Assigned to: subkingdom Adictyozoa subkingdom Dictyozoa branch Parabasalia

Characterist

lacks Golgi dictyosome

has Golgi di osomes lacks mitochondr

3 Brown algae is a member of the kingdom Chromista. By 1981, Cavalier-Smith had divided the domain Eukaryota into nine kingdoms. [14] By 1993, he reduced the total number of eukaryote kingdoms down to six. He also classified the domains Eubacteria and Archaebacteria as kingdoms, adding up to a total of eight kingdoms of life: 1. Plantae, 2. Animalia, 3. Protozoa, 4. Fungi, 5. Eubacteria, 6. Archaebacteria, 7. Chromista, and 8. Archezoa. Cavalier-Smith’s new classification scheme retained the plant, animal and fungal kingdoms from the traditional five kingdom model. It also split the kingdom Monera into the two groups, eubacteria and archaebacteria, as proposed by Woese and Fox. In addition it split the kingdom protists into three new kingdoms: archezoa, protozoa, and chromista. Most chromists are photosynthetic. This distinguishes them from most other protists. In both plants and chromists photosynthesis takes place in chloroplasts. In plants, however, the chloroplasts are located in the cytosol while in chromists the chloroplasts are located in the lumen of their rough endoplasmic reticulum. This distinguishes chromists from plants. [5]

Euglenozoa

subkingdom Dictyozoa branch Bikonta infrakingdom Euglenozoa

has Golgi dictyosome mostly with tochondria with trans-s cing of miniexons

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Opalozoa (flagellates)

subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa parvkingdom Ciliomyxa

has Golgi dictyosome tubular mito chondrial cr with cis-spl introns predominan ciliated, no cortical alveoli

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Mycetozoa (slime molds)

subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa parvkingdom Ciliomyxa

has Golgi dictyosome tubular mito chondrial cr with cis-spl introns predominan ciliated, no cortical alveoli

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Choanozoa subkingdom Dictyozoa (choanoflagellates) branch Bikonta infrakingdom Neozoa parvkingdom Ciliomyxa

has Golgi dictyosome flattened m chondrial cr with cis-spl introns predominan

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From Wikipedia, the free encyclopedia
ciliated, 14 Entamoebia no cortical alveoli 7 Dinozoa subkingdom Dictyozoa (Dinoflagellata and branch Bikonta Protalveolata) infrakingdom Neozoa parvkingdom Alveolata

Thomas Cavalier-Smith
subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa Reassigned parvkingdom Entamoebia

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Apicomplexa

subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa parvkingdom Alveolata

has Golgi dictyosomes to Miozoa tubular mitoin Alveolchondrial cristae ata. [17] with cis-spliced introns with cortical alveoli 15 Myxosporidia subkingdom Dictyozoa has Golgi Reassigned branch Bikonta dictyosomes to Miozoa tubular mitoin Alveol- infrakingdom Neozoa parvkingdom Myxozoa chondrial cristae ata. [17] with cis-spliced introns with cortical alveoli 16 Haplosporidia subkingdom Dictyozoa has Golgi Reassigned branch Bikonta dictyosomes to Alveolinfrakingdom Neozoa tubular mitoata. [17] parvkingdom Myxozoa chondrial cristae with cis-spliced introns with cortical alveoli 17 Paramyxia has Golgi

has Golgi dictyosome with cis-spl introns no mitochon dria, peroxi somes, hydr genosomes cilia transie intranuclea centrosome

has Golgi dictyosome with cis-spl introns end rasitic, mult lular spores tochondria, and no cilia

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Ciliophora

subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa parvkingdom Alveolata

has Golgi dictyosome with cis-spl introns end rasitic, mult lular spores tochondria, and no cilia

10 Rhizopoda (lobose and filose amoebae)

subkingdom Dictyozoa branch Bikonta dictyosomes infrakingdom Neozoa usually with tuparvkingdom Neosarcodina bular cristae with cis-spliced introns subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa parvkingdom Neosarcodina has Golgi dictyosomes 18 Mesozoa usually with tubular cristae with cis-spliced introns

subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa parvkingdom Myxozoa

11 Reticulosa (foraminifera; reticulopodial amoebae)

has Golgi dictyosome with cis-spl introns end rasitic, mult lular spores tochondria, and no cilia

subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa parvkingdom Mesozoa

12 Heliozoa

subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa parvkingdom Actinopoda

13 Radiozoa

subkingdom Dictyozoa branch Bikonta infrakingdom Neozoa parvkingdom Actinopoda

has Golgi dictyosomes mostly with mitochondria with cis-spliced introns has axopodia The phylum Opalozoa was established by Cavalier-Smith has 1991. [19] in Golgi dictyosomes mostly with mitochondria with cis-spliced introns By 1998, Cavalier-Smith had reduced the total number of has axopodia kingdoms from eight down to six : Animalia, Protozoa,

has Golgi dictyosome with cis-spl introns tubular mito chondrial cr multicellula with no coll genous conn ive tissue

Cavalier-Smith’s six kingdom models

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From Wikipedia, the free encyclopedia
Fungi, Plantae (including red and green algae), Chromista and Bacteria. [18] Five of Cavalier-Smith’s kingdoms are classified as eukaryotes as shown in the following scheme: • Eubacteria • Neomura • Archaebacteria • • • Unikonts (heterotrophs) • • • Bikonts (primarily photosynthetic) • (including red and green algae) • Eukaryotes are divided into two major groups: unikonts and bikonts. Uniciliates are cells with only one flagellum and unikonts are descended from uniciliates. Unikont cells often have only one centriole as well. Biciliate cells have two flagella and bikonts are descended from biciliates. Biciliates undergo ciliary transformation by converting a younger anterior flagellum into a dissimilar older posterior flagellum. Animals and fungi are unikonts while plants and chromista are bikonts. Some protozoa are unikonts while others are bikonts. The Bacteria (= prokaryotes) are subdivided into Eubacteria and Archaebacteria. According to Cavalier-Smith, eubacteria is the oldest group of terrestrial organisms still living. He classifies the groups which he believes are younger (archaebacteria and eukaryotes) as neomura.

Thomas Cavalier-Smith
• Lobopoda (onychophorans and tardigrades) and recognized a total of 23 animal phyla. [18]

Kingdom protozoa
Under Cavalier-Smith’s proposed classification system, protozoa share the following traits: • they have or are descended from organisms with mitochondria • they have or are descended from organisms with peroxisomes • they lack collagenous connective tissue • they lack epiciliary retronemes (rigid thrustreversing tubular ciliary hairs) • they lack two additional membranes outside their chloroplast envelope Organisms that do not meet these criteria were reassigned to other kingdoms by Cavalier-Smith.

His 2003 model
Kingdom protozoa
In 1993, Cavalier-Smith divided the kingdom Protozoa into two subkingdoms and 18 phyla. [5] By 2003 he used phylogenic evidence to revise the total number of proposed phyla down to 11: Amoebozoa, Choanozoa, Cercozoa, Retaria, Loukozoa, Metamonada, Euglenozoa, Percolozoa, Apusozoa, Alveolata, Ciliophora, and Miozoa.
[17]

Amoebas

His 1998 model
Kingdom animalia
In 1993, Cavalier-Smith classified Myxozoa as a protozoan parvkingdom. By 1998, he had reclassified it as an animal subkingdom. Myxozoa contains three phyla, Myxosporidia, Haplosporidia, and Paramyxia, which were reclassified as animals along with Myxozoa. Likewise, Cavalier-Smith reclassified the protozoan phylum Mesozoa as an animal subkingdom. In his 1998 scheme, the animal kingdom was divided into four subkingdoms: • Radiata (phyla Porifera, Cnidaria, Placozoa, and Ctenophora), • Myxozoa, • Mesozoa, and • Bilateria (all other animal phyla). He created three new animal phyla: • Acanthognatha (rotifers, acanthocephalans, gastrotrichs, and gnathostomulids), • Brachiozoa (brachiopods and phoronids), and

Amoebas do not have flagella and are difficult to classify as unikont or bikont based on morphology. In his 1993 classification scheme, Cavalier-Smith incorrectly classified amoebas as bikonts. Gene fusion research later revealed that the clade Amoebozoa, was ancestrally uniciliate. In his 2003 classification scheme, Cavalier-Smith reassigned Amoebozoa to the unikont clade along with animals, fungi, and the protozoan phylum Choanozoa. Plants and all other protists where assigned to the clade Bikont by Cavalier-Smith. [17] Cavalier-Smith’s 2003 classification scheme: • Unikonts • protozoan phylum Amoebozoa (ancestrally uniciliate) • opisthokonts • uniciliate protozoan phylum Choanozoa • kingdom Fungi • kingdom Animalia • Bikonts • protozoan infrakingdom Rhizaria • phylum Cercozoa • phylum Retaria (Radiozoa and Foraminifera)

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From Wikipedia, the free encyclopedia
• protozoan infrakingdom Excavata • phylum Loukozoa • phylum Metamonada • phylum Euglenozoa • phylum Percolozoa • protozoan phylum Apusozoa (Thecomonadea and Diphylleida) • the chromalveolate clade • kingdom Chromista (Cryptista, Heterokonta, and Haptophyta) • protozoan infrakingdom Alveolata • phylum Ciliophora • phylum Miozoa (Protalveolata, Dinozoa, and Apicomplexa) • kingdom Plantae (Viridaeplantae, Rhodophyta and Glaucophyta)
Cladogram

Thomas Cavalier-Smith
Eubacteria and Archaebacteria together make up the Bacteria kingdom. All remaining leaves together make up the protozoa kingdom.

Rooting the tree of life
In 2006, Cavalier-Smith proposed that the last common ancestor to all terrestrial organisms was a non-flagellate negibacterium with two membranes. [21]

Work (samples)
• Kingdom protozoa and its 18 phyla [1] [2], Microbiol Mol Biol Rev. 1993 December; 57(4): 953-994

By September of 2003, Cavalier-Smith’s tree of life looked like this: [20]

Footnotes
[1]

The Committee on the International Prize for Biology of Japan Society for the Promotion of Eubacteria Science awards the 2004 International Prize for Biology in the field of "Systematic Biology and Taxonomy" to Prof. Thomas Cavalier-Smith, Neomura Archaebacteria Department of Zoology, University of Oxford, UK. Retrieved December 9, 2006. Eukarya Bikonts Apusozoa [2] Zrzavý, J (2001). The interrelationships of metazoan parasites: a review of phylum- and Cabozoa higher-level hypotheses from recent Excavata morphological and molecular phylogenetic analyses. Folia Parasitol. 48: 81-103. Eukarya Rhizaria Retaria [3] Patterson, DJ (1999). The diversity of eukaryotes. Amer. Naturalist 65: S96-S124. Apusomonadida, Cercozoa Eukarya. [4] Origins of the Eukarya Cited on February 9, 2009. [5] ^ T. Cavalier-Smith. Kingdom protozoa and its 18 Kingdom phyla. Microbiol Mol Biol Rev. 1993 December; 57(4): Plantae 953-994. | Full Text Chromalveolata Kingdom [6] Thomas Cavalier-Smith. Only six kingdoms of life. Chromista Proc. R. Soc. Lond. B (2004) Alveolata [7] Dan H. Nicolson. Animal, Vegetable or Mineral?. Proceedings of a Mini-Symposium on Biological Nomenclature in the 21st Century held at the Unikonts Amoebozoa University of Maryland on 4 November 1996. Edited by James L. Reveal Opisthokonts [8] ^ Joseph M. Scamardella. Not plants or animals: a Choanozoa brief history of the origin of Kingdoms Protozoa, Protista and Kingdom Animalia Protoctista. INTERNATL MICROBIOL (1999) 2:207–216. [9] ^ Douglas A. Penny and Regina Waern. Biology. An Kingdom Fungi Introduction to aspects of Modern Biological Science. (1965) Pitman Publishing. Vancouver Calgary Toronto Montreal. Pages 626-640. In the above tree, the traditional plant, animal, and [10] R. H. Whittake. On the Broad Classification of fungal kingdoms, as well as Cavalier-Smith’s proposed Organisms. The Quarterly Review of Biology, Vol. 34, Chromista kingdom, are shown as leaves. The leaves No. 3 (Sep., 1959), pp. 210-226.

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From Wikipedia, the free encyclopedia
[11] Benjamin S. Weeks, and I. Edward Alcamo. Microbes and Society, Second Edition. Page 32. [12] ^ Woese C, Kandler O, Wheelis M (1990). "Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya.". Proc Natl Acad Sci U S A 87 (12): 4576–9. doi:10.1073/pnas.87.12.4576. PMID 2112744. http://www.pnas.org/cgi/reprint/87/12/4576. [13] Gert Korthof, (2007). Carl Woese: from scientific dissident to textbook orthodoxy. Cited February 11, 2009. [14] Cavalier-Smith T. Eukaryote kingdoms: seven or nine? Biosystems. 1981;14(3-4):461-81. [Additional Related Articles ] [15] Cavalier-Smith T, Chao EE. Molecular phylogeny of the free-living archezoan Trepomonas agilis and the nature of the first eukaryote. J Mol Evol. 1996 Dec;43(6):551-62. [16] Thomas Cavalier-Smith. Only six kingdoms of life. Proc. R. Soc. Lond. B (2004) [17] ^ Thomas Cavalier-Smith, [http://www.sciencedirect.com/

Thomas Cavalier-Smith

[18] [19]

[20]

[21]

science?_ob=ArticleURL&_udi=B7GW3-4DPMCR2-3V&_user=10&_ Protist phylogeny and the high-level classification of Protozoa], Europ. J. Protistol. 39, 338-348 (2003). ^ T. CAVALIER-SMITH. A revised six-kingdom system of life. Biological Reviews (1998), 73 : 203-266. T. Cavalier-Smith. The Protozoan Phylum Opalozoa. Journal of Eukaryotic Microbiology Volume 40 Issue 5, Pages 609 - 615. Alexandra Stechmann and Thomas Cavalier-Smith. The root of the eukaryote tree pinpointed. Current Biology Vol 13 No 17. T. Cavalier-Smith. Rooting the tree of life by transition analyses Biology Direct 2006, 1:19

External links
• University of Oxford Faculty Web Page for T. Cavalier-Smith • T. Cavalier-Smith on Google Scholar

Retrieved from "http://en.wikipedia.org/wiki/Thomas_Cavalier-Smith" Categories: Geneticist and evolutionary biologist stubs, English biologists, Evolutionary biologists, Fellows of the Royal Society, Academics of the University of Oxford, 1942 births, Living people This page was last modified on 30 April 2009, at 17:36 (UTC). All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.) Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a U.S. registered 501(c)(3) tax-deductible nonprofit charity. Privacy policy About Wikipedia Disclaimers

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