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Zygnematales: Difference between revisions

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Category:Green algae orders
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| classis = [[Zygnematophyceae]]
| classis = [[Zygnematophyceae]]
| ordo = '''Zygnematales'''
| ordo = '''Zygnematales'''
| ordo_authority = Bessey, 1907
| subdivision_ranks = Families
| subdivision_ranks = Families
| subdivision =
| subdivision =
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*[[Peniaceae]]
*[[Peniaceae]]
*[[Zygnemataceae]]
*[[Zygnemataceae]]
| synonyms = ''Zygnematales'' <small>Borge and Pascher, 1913<small>
}}
}}

The '''Zygnematales''' ({{lang-el|ζυγός}} (zygos) + ''νήμα'' (nēma) ([[nominative|nom.]]), ''νήματος'' (nēmatos) ([[genitive|gen.]])), also called the '''Conjugales''', are an [[order (biology)|order]] of [[green alga]]e,<ref name="pmid16236178">{{cite journal |author=Turmel M, Otis C, Lemieux C |title=The complete chloroplast DNA sequences of the charophycean green algae Staurastrum and Zygnema reveal that the chloroplast genome underwent extensive changes during the evolution of the Zygnematales |journal=BMC Biol. |volume=3|pages=22 |year=2005 |pmid=16236178 |pmc=1277820 |doi=10.1186/1741-7007-3-22 |url=http://www.biomedcentral.com/1741-7007/3/22}}</ref> comprising several thousand different [[species]] in [[genus|genera]] such as the well-known ''Zygnema'' and ''[[Spirogyra]]''. Most members of this group develop into unbranched filaments, one cell thick, which grow longer through normal [[cell division]]. Most live in [[freshwater]], and form an important component of the algal scum that grows on or near plants, rocks, and various debris.{{clarify|reason=various debris is vague, undefined|date=April 2014}}
The '''Zygnematales''' ({{lang-el|ζυγός}} (zygos) + ''νήμα'' (nēma) ([[nominative|nom.]]), ''νήματος'' (nēmatos) ([[genitive|gen.]])), also called the '''Conjugales''', are an [[order (biology)|order]] of [[green alga]]e,<ref name="pmid16236178">{{cite journal |author=Turmel M, Otis C, Lemieux C |title=The complete chloroplast DNA sequences of the charophycean green algae Staurastrum and Zygnema reveal that the chloroplast genome underwent extensive changes during the evolution of the Zygnematales |journal=BMC Biol. |volume=3|pages=22 |year=2005 |pmid=16236178 |pmc=1277820 |doi=10.1186/1741-7007-3-22 |url=http://www.biomedcentral.com/1741-7007/3/22}}</ref> comprising several thousand different [[species]] in [[genus|genera]] such as the well-known ''Zygnema'' and ''[[Spirogyra]]''. Most members of this group develop into unbranched filaments, one cell thick, which grow longer through normal [[cell division]]. Most live in [[freshwater]], and form an important component of the algal scum that grows on or near plants, rocks, and various debris.{{clarify|reason=various debris is vague, undefined|date=April 2014}}



Revision as of 15:11, 20 February 2016

Zygnematales
Spirogyra green algae
Scientific classification
Kingdom:
Division:
Class:
Order:
Zygnematales

Bessey, 1907
Families
Synonyms

Zygnematales Borge and Pascher, 1913

The Zygnematales (Template:Lang-el (zygos) + νήμα (nēma) (nom.), νήματος (nēmatos) (gen.)), also called the Conjugales, are an order of green algae,[1] comprising several thousand different species in genera such as the well-known Zygnema and Spirogyra. Most members of this group develop into unbranched filaments, one cell thick, which grow longer through normal cell division. Most live in freshwater, and form an important component of the algal scum that grows on or near plants, rocks, and various debris.[clarification needed]

Systematically they fall within the division Charophyta, which includes the groups of algae that are most closely related to the higher plants. Charophyta are included with land plants (Embryophyta) in the clade Streptophyta.[2]

Sexual reproduction in Zygnematales takes place through a process called conjugation.[3] Here filaments of opposite gender line up, and tubes form between corresponding cells. The male cells then become amoeboid and crawl across, or sometimes both cells crawl into the tube. The cells then meet and fuse to form a zygote, which later undergoes meiosis to produce new filaments. As in plants, only the female passes chloroplasts on to the offspring.[citation needed]

The only other group of conjugating algae are the desmids, which live as individual cells often with a striking symmetrical appearance. The desmids are sometimes placed in a separate order Desmidiales, which is closely related to Zygnematales, and the two are placed together in the class Zygnematophyceae.

References

  1. ^ Turmel M, Otis C, Lemieux C (2005). "The complete chloroplast DNA sequences of the charophycean green algae Staurastrum and Zygnema reveal that the chloroplast genome underwent extensive changes during the evolution of the Zygnematales". BMC Biol. 3: 22. doi:10.1186/1741-7007-3-22. PMC 1277820. PMID 16236178.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link)
  2. ^ http://esciencenews.com/articles/2011/04/17/ancestors.land.plants.revealed
  3. ^ Kapraun DF (April 2007). "Nuclear DNA Content Estimates in Green Algal Lineages: Chlorophyta and Streptophyta". Ann. Bot. 99 (4): 677–701. doi:10.1093/aob/mcl294. PMC 2802934. PMID 17272304.