DESCRIPTION OF THE SUPERGROUP CHROMALVEOLATA (ADL ET AL. 2005)
| EUKARYA> CHROMALVEOLATA |
SUPERGROUP CHROMALVEOLATA LINKS
| Chromalveolata (krom-al-ve-o-LA-tuh) is formed from two roots (one Greek and the other Latin) that mean “color” (chroma -χρώμα) and a small cavity (alveolus). The references are to the bag-like sacs that underlie the cell membrane and that many taxa are pigmented (photosynthetic). |
| INTRODUCTION TO THE CHROMALVEOLATA The Chromalveolata includes four kingdoms: Heterokontae, Alveolatae, Rhizariae, and Hacrobiae (also called Hacrobia-by Cavalier-Smith 2010b) whose taxa may be photosynthetic, parasitic, saprophytic, or heterotrophic. They range in form from unicells to some of the largest multicellular organisms on earth. Photosynthetic cells within this supergroup tend to use chlorophylls a (text with tooltip) Chlorophyll A is a primary photosynthetic pigment of all photosynthetic eukaryotes (in the chloroplasts) and Cyanobacteria. It is membrane-bound on thyllakoids and absorbs mainly in the blue and red ranges of visible light. Its structure is that of a tetrapyrrole with a magnesium in the center. That is bound to a long aliphatic alcohol (phytol). Chlorophylls a, b, c, d, and e, together with the bacteriochlorophylls have similar structures and vary only in the structures of their side chains. and c (text with tooltip) Chlorophyll C is a variant of Chlorophyll A. and a secondary photosynthetic pigment in the many of the photosynthetic heterokonts and dinoflagellates. See Chlorophyll A. , a characteristic that served to associate them through much of the 20th Century. Pascher et al. (1914) united many of the photosynthetic taxa with other nonphotosynthetic taxa on the basis of their distinctive motile cells: biflagellate with an anteriorly-directed (text with tooltip) An anteriorly-directed flagellum extends in the direction of the motion of the motile cell. The interpretation is that the flagellum functions by pulling the cell. tinsel flagellum (text with tooltip) A tinsel flagellum is one that is covered with flagellar hairs and thus appears thicker in light microscopy. Usually, tinsel flagella are anteriorally-directed. and a posteriorly-directed (recurrent) (text with tooltip) Recurrent flagella bend to the posterior end of the cell. Typically, they are identified as recurrent when anteriorly-directed flagella are present. whiplash flagellum (text with tooltip) (1) A whiplash flagellum is a eukaryotic 9+2 flagellum with few or no flagellar hairs or scales. These may be directed anteriorly or posteriorly.<br>(2) A whiplash flagellum is free of hair-like mastigonemes and usually is trailing or posteriorly-directed. . Informally, they were called the chromophytes (literally meaning colored plants), because the photosynthetic taxa were colors other than green (e.g. brown, golden, etc.). Christensen (1962) formally defined the Division (a Botanical hierarchical name that approximately equals a phylum) and named it Chromophyta. Later, Cavalier-Smith (1989) created the Kingdom Chromista, a taxon that contained all of the heterokonts and eukaryomonads. Then, the alveolates began to come together as a group based on speculation by Taylor (1976) and later by Gajadhar et al. (1991). The association between the heterokonts and alveolates developed from 1999-2005 (Taylor, 1999; Patterson, 1999; Baldauf, 2003a; Keeling, 2004; and Harper et al., 2005). Harper et al. (2005) show convincing evidence that the heterokont+alveolate clade is monophyletic and weakly associated with the eukaryomonads. Also, Hackett et al. (2007) and Burki et al. (2007) show the association of the Rhizaria with the Chromalveolata into a clade referred to as the RAS group (abbreviation for Rhizarians-Alveolates-Stramenopiles1 ; other permutations such as SAR are used). Cavalier-Smith (2010b) also formalized the SAR clade with the name Harosa that is sister to the haptomonad + cryptomonad clade which he calls Hacrobia (see Figure 1). At present, the chromalveolates do not seem to have a defining synapomorphy. Table 1 shows three common characters (photosynthesis, cell covering, and flagella) in the whole supergroup. |
| TABLE 1. A list of major groups of chromalveolate taxa. We have indicated as to whether they are photosynthetic, type of cell covering, and flagella. | |||
| TAXA | PHOTOSYNTHETIC | CELL COVERING | FLAGELLA |
| CRYPTOMONADS | +/- | ORGANIC PELLICLE (text with tooltip) A pellicle is a complex outer cellular covering that occurs within the bounds of the plasmalemma. Often synonymous with the term theca, a pellicle defines such groups as the euglenoid-kinetoplastid clade amd the Kingdom Alveolatae. | 2 ANTERIOR, WITH MASTIGONEMES (text with tooltip) Mastigonemes are flagellar hairs. |
| HAPTOMONADS | + | CALCIUM CARBONATE SCALES (text with tooltip) Protist scales are regular overlapping structures on the outside of the cell. They may be organic, silicaceous, or carbonaceous and may serve as an articulated cell wall. Scales may occur on the cells of a range of unrelated taxa. | 2 ANTERIOR WHIPLASH (text with tooltip) (1) A whiplash flagellum is a eukaryotic 9+2 flagellum with few or no flagellar hairs or scales. These may be directed anteriorly or posteriorly. (2) A whiplash flagellum is free of hair-like mastigonemes and usually is trailing or posteriorly-directed. WITH HAPTOMENA (text with tooltip) A haptonema is a flagellum-like structure that characterizes the Haptotista. The formula for the axonemal microtubular array is 6(1)+0. Usually functions as a holdfast. |
| CILIATES | – | ALVEOLI (text with tooltip) Alveoli (n.) are membrane-bound sacs that lie beneath the plasmalemma in the Kingdom Alveolata (Dinoflagellates, Ciliates, and Apicomplexans). The presence of alveoli appears to be one of the defining synapomorphies of the group. | PAIRED, UNIFORM AND UNITED IN KINETIES |
| DINOFLAGELLATES | +/- | ALVEOLI, SOME WITH CELLULOSIC PLATES (text with tooltip) Armored dinoflagellates have cellulosic plates that fill the alveoli. The architecture of the particular plates is conserved within the species such that they can be determined according to the tabulation. The plates have flanges that allow them to overlap adjacent ones. Also, they are perforated with holes that allow for the discharge of trichocysts. | 1 LATERAL RIBBON (text with tooltip) The ribbon-like flagellum is a tinsel (with flagellar hairs) flagellum and is flattened. Although it occurs in several groups of microbial eukaryotes, it is characteristic of dinoflagellates where it lies in the cingulum. AND 1 TRAILING WHIPLASH |
| APICOMPLEXA | – (HAVE NON PHOTOSYNTHETIC PLASTID | ALVEOLI | ? FOUND ONLY IN SPERM CELLS |
| OPALINIDS | – | PLEATED PELLICLE | UNIFORM FLAGELLA ARRANGED IN KINETIES (text with tooltip) Kineties (kinety) provide the underlying structure of flagellar roots found in ciliates (and others like the pseudociliata) and allow for coordination of the flagella. |
| LABYRINTHULOMORPHS | – | NAKED WITH SECRETED SLIME COVERING | GAMETES; ANTERIOR TINSEL AND RECURRENT WHIPLASH |
| BICOECIDS | – | NAKED WITH LORICA (text with tooltip) A lorica is a covering that occurs outside of the cell membrane. It is secreted by the cell and usually is organic. Loricas do not completely enclose the cell. Periplasts, structures similar to loricas do enclose the cell. | ANTERIOR TINSEL; RECURRENT WITHIN LORICA |
| OOMYCOTES | – | WALL: CELLULOSE AND/OR CHITIN | SPORES; ANTERIOR TINSEL; SOMETIMES RECURRENT WHIPLASH |
| CHRYSOPHYTES | + | SILICACEOUS (text with tooltip) Silica is silicon dioxide. SCALES, LORICA, OR NAKED | ANTERIOR TINSEL AND RECURRENT WHIPLASH |
| RAPHIDIOPHYTES | + | NAKED | ANTERIOR TINSEL AND RECURRENT WHIPLASH |
| XANTHOPHYTES | + | CELLULOSE? | SPORES AND GAMETES; ANTERIOR TINSEL AND RECURRENT WHIPLASH |
| EUSTIGS | + | CELLULOSE? | ZOOSPORES (text with tooltip) A zoospore is an asexual spore that is motile. Zoo- (pronoumced zo-o) is a prefix that means moving. ; ANTERIOR TINSEL AND (+/-) RECURRENT WHIPLASH |
| PHAEOPHYTES | + | THICK MUCILAGINOUS CELL WALL | SPORES AND GAMETES; ANTERIOR TINSEL AND POSTERIOR WHIPLASH |
| DIATOMS | + | OVERLAPPING SILICACEOUS HALVES | RECURRENT WHIPLASH IN CENTRIC SPERM ONLY |
| CERCOZOANS | ONE GROUP ONLY | MOST NAKED; SOME WITH SILICACEOUS SCALES, ORGANIC TESTS, ETC. | MOST WITH 2 HETERODYNAMIC FLAGELLA |
| ENDOMYXANS | – | NAKED; SOME WITH ORGANIC CYST OR SPORE | SOME WITH 2 HETERODYNAMIC FLAGELLA |
| FORAMINIFERANS | SOME WITH PHOTOSYNTHETIC SYMBIONTS | NAKED BUT INTERNAL TEST OF CALCIUM CARBONATE | GAMETES WITH 2 HETERODYNAMIC FLAGELLA |
| RADIOLARIANS | SOME WITH PHOTOSYNTHETIC SYMBIONTS | NAKED BUT INTERNAL SKELETON OF SILICON DIOXIDE OR STRONTIUM SULFATE | ZOOSPORES WITH 2 HETERODYNAMIC FLAGELLA |
FIGURE 1. Topology of the kingdoms of the Chromalveolata. Relationships between the clades of the Harosa (Rhizariae, Heterokontae, and Alveolatae, Cavalier-Smith 2010b) are from Burki et al. (2010). The sister relationship between Harosa and Hacrobia is from Cavalier-Smith (2010b)
| KINGDOMS OF THE CHROMALVEOLATA |
- KINGDOM ALVEOLATAE (CAVALIER-SMITH 1991)
KINGDOM HETEROKONTAE1 (CAVALIER-SMITH 1986)
KINGDOM RHIZARIAE (CAVALIER-SMITH 1993)
KINGDOM HACROBIAE (CAVALIER-SMITH 2010)
| 1. Stramenopile is another name for the Heterokonts. We have kept the name coined by Cavalier-Smith (1986). |
| LITERATURE CITED Baldauf, S. L. 2003a. The deep roots of eukaryotes. Science. 300 (5626): 1701-1703. Baldauf, S. 2008. An overview of the phylogeny and diversity of eukaryotes. Journal of Systematics and Evolution. 46(3): 263-273. Burki, F., K. Shalchian-Tabrizi, M. Minge, A. Skaeveland, S. I. Nikolaev, K. S. Jakobsen, and J. Pawlowski. 2007. Phylogenomics reshuffles the eukaryotic supergroups. PLoS ONE. 8:790-795. Burki, F., A. Kudryavtsev, M. V. Matz, G. V. Aglyamova, S. Bulman, M. Fiers, P. J. Keeling, J. Pawlowski. 2010. Evolution of Rhizaria: new insights from phylogenomics analysis of uncultivated protists. BMC Evolutionary Biology. 10.377 http://www,biomedcentral.com/1471-2148/10/377 Cavalier-Smith, T. 1986a. The kingdom Chromista: origin and systematics. In: F. E. Round and D. J. Chapman, eds. Progress in Phycological Research. BioPress Ltd. Bristol, UK. vol. 4, 309–347. Cavalier-Smith, T. 1989. The Kingdom Chromista. In: Green, J.C., B.S.C. Leadbeater, and W.L. Diver, eds. The Chromophyte Algae: Problems and Perspectives. Systematics Association Special Volume No. 38. Clarendon Press. Oxford. pp. 381-407. Cavalier-Smith, T. 1993a. Kingdom protozoa and its 18 Phyla. Microbiological Reviews. 57: 953-994. Cavalier-Smith, T. 2010b. Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree. Biology Letters. 6: 342-345. Cristensen, T. 1962. Alger. In: Boscher, T. W., M. Lange, and T. Sorensen, eds. Botanik Bd 2. Systematisk Botanik. No. 2. Munksgaard, Copenhagen. pp. 1-178. Gajadhar, A. A., W. C. Marquardt, R. Hall, J. Gunderson, E. V. A. Carmona, and M. L. Sogin. 1991. Ribosomal RNA sequences of Sarcocystis muris, Theileria annulata, and Crypthecodinium cohnii reveal evolutionary relationships among apicomplexans, dinoflagellates, and ciliates. Molecular and Biochemical Parasitology. 45:147-154. Hackett, J. D., H. S. Yoon, S. Li, A. Reyes-Prieto, S. E. Rummele, and D. Bhattacharya. 2007. Phylogenomic analysis supports the monoplyly of Cryptophytes and Haptophytes and the association of Rhizaria with Chromalveolates. Molecular Biology and Evolution. 24(8): 1702-1713. Harper, J. T., E. Waanders, and P. J. Keeling. 2005. On the monophyly of chromalveolates using a six-protein phylogeny of eukaryotes. International Journal of Systematic and Evolutionary Microbiology. 55: 487-496. Keeling P. J. 2004 The diversity and evolutionary history of plastids and their hosts. American Journal of Botany. 91(10): 1481-1493. Pascher. A., J. Schiller, and W. Migula. 1914. Heterokontae, Phaeophyta, Rhodophyta, Charophyta. In: Pascher, A. ed. Susswasserflora, Deutschlands, Osterreichs und der Schweiz. Heft 11. Verlag Von Gustav Fischer. Jena. Taylor, F. J. R. 1976. Flagellate Phylogeny: A Study in Conflicts. Journal of Protozoology. 23(1):28-40. Taylor, F. J. R. 1999. Ultrastructure as a control for protistan molecular phylogeny. The American Naturalist. 154(supplement): S125-S136. |
| By Jack R. Holt. Last revised: 02/16/2015 |
