Ornamental algae

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Ornamental algae
Micrasterias in the light microscope

Micrasterias in the light microscope

Systematics
without rank: Diaphoreticks
without rank: Archaeplastida
without rank: Chloroplastida
without rank: Charophyta
without rank: Phragmoplastophyta
without rank: Ornamental algae
Scientific name
Zygnematophyceae
Round , 1971

The ornamental algae (Zygnematophyceae) were traditionally placed among the green algae , but belong to the derived group of Charophyta and are therefore closer to the higher plants . An older name for the group is Conjugatae . The two orders of ornamental algae (Desmidiales) and Jochalgae (Zygnematales) belong to it .

features

Common morphological features of the two orders are the absence of flagellated stages; Sexual reproduction takes place via conjugation , the fusion of non-flagellated gametes, which passively or actively reach one another through tubes or mucous membranes. The entire cell content of certain cells (gametocysts) is transformed into a non-flagellated gamete. All gametes are designed alike. The merging of two gametes is called conjugation in this case. The diploid zygote is a thick-walled permanent zygote. Vegetative reproduction occurs through simple cell division.

The representatives Zygnematophyceae are single-celled or filamentous algae, the filaments are always unbranched, single-row and easily disintegrate. The chloroplasts have pyrenoids and can be very diverse. Specific inclusions are found in special vacuoles: tannins in Zygnematales, gypsum in some Desmidiales. The cell wall is slimy, layered and smooth (yoke algae) or sculptured (ornamental algae)

Occurrence

The ornamental algae are freshwater inhabitants. They live mainly on the bottom of the water ( benthos ), less often in the free water body ( plankton ). A small number of the species are part of the Edaphon as ground dwellers or part of the cryoflora as colonists on glacier surfaces .

Systematics

The latest molecular biological studies suggest that the Zygnematophyceae could be the sister group to the ancestors of the land plants. Traditionally, this role is attributed to the morphologically more complex candelabrum algae .

With around 4000 species, the ornamental algae are the most species-rich group of algae within the Charophyta . The ornamental algae as well as the order of the ornamental algae are monophyletic , while the yoke algae form a paraphyletic group.

Individual evidence

  1. ^ A b Louise A. Lewis, Richard M. McCourt: Green Algae and the origin of land plants : American Journal of Botany 91 (10), 2004, pages 1535-1556. Abstract and full text
  2. a b c W. Braune, A. Leman, H. Taubert: Plant anatomical internship II . 3rd edition, VEB Gustav Fischer Verlag, Jena 1990, pp. 85-88, ISBN 3-334-00301-9
  3. Norman J. Wickett, Siavash Mirarab, Nam Nguyen, Tandy Warnow, Eric Carpenter, Naim Matasci, Saravanaraj Ayyampalayam, Michael S. Barker, J. Gordon Burleigh, Matthew A. Gitzendanner, Brad R. Ruhfel, Eric Wafula, Joshua P. Der, Sean W. Graham, Sarah Mathews, Michael Melkonian, Douglas E. Soltis, Pamela S. Soltis, Nicholas W. Miles, Carl J. Rothfels, Lisa Pokorny, A. Jonathan Shaw, Lisa DeGironimo, Dennis W. Stevenson, Barbara Surek, Juan Carlos Villarreal, Béatrice Roure, Hervé Philippe, Claude W. dePamphilis, Tao Chen, Michael K. Deyholos, Regina S. Baucom, Toni M. Kutchan, Megan M. Augustin, Jun Wang, Yong Zhang, Zhijian Tian, ​​Zhixiang Yan, Xiaolei Wu, Xiao Sun, Gane Ka-Shu Wong and James Leebens-Mack: Phylotranscriptomic analysis of the origin and early diversification of land plants . PNAS 2014 111 (45) E4859-E4868; published ahead of print October 29, 2014, doi : 10.1073 / pnas.1323926111
  4. Richard M. McCourt, Kenneth G. Karol, Jeremy Bell, Kathleen M. Helm-Bychowski, Anna Grajewska, Martin F. Wojciechowski, Robert W. Hoshaw: Phylogeny of the conjugating Green Algae (Zygnemophyceae) based on rbcL sequences . In: Journal of Phycology , Volume 36 (4), 200, pp. 747-758. doi : 10.1046 / j.1529-8817.2000.99106.x ; Andrey A. Gontcharov, Birger Marin, Michael Melkonian: Molecular Phylogeny of Conjugating Green Algae (Zygnemophyceae, Streptophyta) Inferred from SSU rDNA Sequence Comparisons . In: Journal of Molecular Evolution , Volume 56, 2002, pp. 89-104. doi : 10.1007 / s00239-002-2383-4

Web links

Commons : Ornamental Algae (Zygnematophyceae)  - Collection of images, videos and audio files