Protoctists

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The division of living beings into systematics is a continuous subject of research. Different systematic classifications exist side by side and one after the other. The taxon treated here has become obsolete due to new research or is not part of the group systematics presented in the German-language Wikipedia.

Not to be confused with protists

As Protoctista (Protoctista) are all eukaryotic beings referred, not to the animals , plants or fungi belong. It is therefore a systematic term in the rank of an empire , but is not a taxon in the phylogenetic sense. It includes algae (from unicellular to large, multicellular seaweed ), ciliates , foraminifera , apicomplexa , egg fungi and slime molds .

The Protoctists are compared to 4 other realms:

  • Monera : all prokaryotes ,
  • Fungi : Fungi as haploid or diploid organisms that develop from spores and do not have flagella at any stage of development,
  • Animalia : animals as diploid creatures that develop from blastular embryos,
  • Plantae : Plants as living beings that develop from embryos surrounded by maternal tissue and in which haplophases and diplophases alternate.

This five-kingdom system in which instead of the Protoctista the kingdom is different from another five-kingdom system, protists is compared with the other four kingdoms (Robert H. Whittaker, 1969). In contrast to Protoctista, the Protista comprise only unicellular, eukaryotic organisms, so this taxon is less extensive than the Protoctista kingdom, which also includes all multicellular algae up to the great seaweed. The reason for the introduction of the Protoctista kingdom in place of the Protista kingdom is that the difference between unicellularity and multicellularity is not sufficient for the division into two different kingdoms and thus related organisms are divided into different high-ranking taxa.

The taxon Protoctista was introduced by John Hogg in 1861 . In 1956 it was redefined by Herbert Faulkner Copeland , who, however, deviated from the current definition, included fungi and excluded green algae . The establishment of the Protoctista Empire in the system of living beings has been increasingly propagated since the mid-1980s, with Lynn Margulis in particular . In today's systematics, however, it is usually not used as a taxon because it is paraphyletic .

Protoctist tribes

According to Margulis et al. (1990) the Protoctists are divided into the following tribes (Phyla):

literature

  • John Hogg: On the distinction of a plant and an animal, and on a fourth kingdom of nature . In: The Edinburgh New Philosophical Journal (new series) . Vol. 12, 1861, pp. 216-225.
  • Herbert Faulkner Copeland: The classification of lower organisms . Pacific Books, Palo Alto 1956.
  • RH Whittaker: New concepts of kingdoms . In: Science . Vol. 163, 1969, pp. 150-160.
  • Lynn Margulis, John O. Corliss, Michael Melkonian, David J. Chapman (Eds.): Handbook of Protoctista; the structure, cultivation, habitats, and life histories of the eukaryotic microorganisms and their descendants exclusive of animals, plants, and fungi; a guide to the algae, ciliates, foraminifera, sporozoa, water molds, slime molds, and the other protoctists. Jones & Bartlett, Boston 1990.