Phycology جلبک شناسی

نخستین پایگاه اطلاعاتی جلبک شناسی به زبان فارسی

Phylogeny and groupin of Algae Patterson 1999

                              Algae

 

 

 

  A polyphyletic grouping of organisms with chloroplasts. In a phylogenetic sense obsolete because the group is both polyphyletic and paraphyletic. It is still in widespread use in some quarters. Now divided into…….

 

 

 

 1. Blue-green algae (bacteria),

Bacterium: organisms with DNA as a loop not included in a nucleus. Also called prokaryotes. Distinguished from eukaryotes which have DNA in a membrane bounded nucleus

Blue-green algae: the cyanobacteria - a type of prokaryote. Not included

 

 

 

 

   2. Cryptomonads,

Cryptomonads - group of flagellates including autotrophs, heterotrophs and autotrophs., not diverse, but abundant and common. Two genera known to be exclusively heterotrophic (Chilomonas and Goniomonas) are heterotrophic.

 

 

 

 

   3. Dinoflagellates (an alveolate group),

Alveolates: A group of protists all with flattened sacs, alveoli, under the cell surface; comprised of the ciliates, dinoflagellates, and the apicomplexa

 

 

 

4. Euglenids ( a group of euglenozoa)

Euglenids - group of autotrophs, heterotrophs and mixotrophs, if autotrophic with plastids with chlorophyll B; assigned to the Euglenozoa.

Euglenozoa: A grouping of flagellates including kinetoplastids, euglenids, diplonemids and Postgaardi.

 

 

 

 

 

5. Stramenopiles, various (also referred to as chromophytes, chrysophytes, heterokonts - including the diatoms and brown algae),

Stramenopiles, a grouping of organisms with tripartite hairs usually associated with the flagella, or derived from such organisms. Large group with an array of trophic strategies, but including the actinophryids, bicosoecids Blastocystis, Chlamydomyxa, chromulinids, chrysophytes sensu lato, Commation, Developayella, diatoms, dictyochales, Diplophrys, hyphochytridiomycetes, labyrinthulids, oomycetes, opalines, Parmales, pedinellids, Pendulomonas, phaeothamniids, brown algae, Pirsonia, proteromonads, raphidiophytes, Reticulosphaera, Rhizochromulina, Siluania, synurids, pelagophytes, thrausochytrids, and the xanthophytes.

Chromophytes: a term used variously to refer to some or all of those algae with chloroplasts having chlorophylls a and c (i.e. stramenopiles, cryptomonads, haptophytes and dinoflagellates)

 

 

 

 

6. Haptophytes (= prasinophytes),

Haptophytes: also called prymnesiophytes, mostly small marine algae with two flagella and an additional locomotor organelle, the haptonema. Includes the coccolithophorids - being those species with calcareous scales. a few taxa are heterotrophic.

Prasinophytes: A type of green alga, only found in marine conditions, part of the Viridiplantae

7. Green algae (viridaeplantae),

Plants: An imprecise term used varyingly from anything with plastids, or more restrictively to that subset being the multicellular taxa with plastids, or more restrictively to the multicellular taxa with plastids with chlorophyll B and cellulosic cell walls, or more restrictively to the sister group to the Charales. The term is here regarded as descriptive and not taxonomic. The most restrictive concept is here part of the Viridiplantae.

Viridaeplantae: the evolutionary lineage of green (with chlorophyll B) algae and plants that include the prasinophytes, chlorophytes and the land plants

 

 

 

 

8. Red algae

Red algae: mostly multicellular algae with phycobilin rich plastids providing generally a pink or red colour.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Algae: Protists with Chloroplasts

David J. Patterson

The algae are a polyphyletic and paraphyletic group of organisms. They are defined in differing ways, but are usually considered to be the photosynthetic organisms excepting plants. Using the term 'plants' in its most restrictive fashion, the algae are then photosynthetic organisms excepting the sister group to the Charales (i.e. the land plants). Such a definition allows inclusion of photosynthetic prokaryotes such as the cyanobacteria. The definition applied here is that the algae is that artificial subset of the photosynthetic eukaryotes which excludes the sister group to the Charales (land plants).

The algae are the dominating primary producers in aquatic ecosystems, on unstable substrates (muds and sands) and in intertidal marine habitats. Algae are commonly exploited as foodstuffs, food additives, toothpastes, etc.

The ability for eukaryotes to carry out photosynthesis was made possible by one or more symbiotic associations between heterotrophic eukaryotes and photosynthetic prokaryotes (or their descendents). There were several primary symbioses between eukaryotes and blue green algae. In one lineage, the photosynthetic organism lost much of its genetic independence and became functionally and genetically integrated as chloroplasts within the host cell. Modern chloroplasts, also called plastids, are bounded by two or more membranes, and most usually lie free in the cytoplasm, but in some cases they may be located within a fold of the nuclear envelope, or may be associated with the cytoplasm and residual nucleus of a eukaryotic endosybiont. The descendents of some of these primary plastids have gone on to form further associations. At least two types of protists (chloroarachniophytes and cryptomonads) have acquired 'plastids' by forming symbioses with eukaryotic algae. This are referred to as secondary symbioses.

Algae are distinguished on a number of different characteristics. The most important ones are:

  • the colour of the plastids (more correctly the combination of photosynthetic pigments that are present in the plastid)
  • the presence of flagella (and if so how many, how do they insert in the cell and how do they beat)
  • is the cell surrounded by extracellular material? If so, what is that material - organic or inorganic, a continuous wall or a layer of scales)
  • are the cells motile or not?
  • do they occur singly, in colonies, filaments or exhibit differentiation that would allow them to satisfy the criterion of multicellularity?

 

Algal protists occur in 8 lineages. These are summarised below.

 

Groups of Algae

GROUP

COMPOSITION

ORGANIZATION

MAJOR PIGMENTS

ALVEOLATES

Contains some algae, autotrophic dinoflagellates, diverse, Peridinium, Symbiodinium, Ceratium

unicellular, colonial, syncytial; free-living, symbiotic and parasitic

chlorophylls a and c, some symbionts

CHLORARACHNIOPHYTES

A few genera of amoeboid organisms all with symbiotic algae, Chlorarachnion

syncytial, free-living

Chlorophyll b

CRYPTOMONADS

About 12 genera of flagellates, Cryptomonas

single cells, rarely forming colonies, some are endobiotic

Chlorophylls a and c, phycobilins

EUGLENIDS

about half of the genera (35) contain members with green chloroplasts, flagellates, Euglena, Trachelomonas

single cells

Chlorophyll b

GLAUCOPHYTES

Several genera of flagellated and non-flagellated protists with similar phycobilin-rich symbionts, e.g. Glaucocystis, Cyanophora

flagellated and non-flagellated cells

Phycobilin

HAPTOPHYTES

Diverse, with many genera, all or all bar one genera with plastids, with naked species and those with scales (coccolithophores)

single cells, some are endosymbionts

Chlorophylls a and c

RED ALGAE (Rhodophyta)

All species are regarded as algal

free-living and parasitic, single celled, and multicellular

Phycobilins

STRAMENOPILES

Most but not all stramenopiles are algae, the group includes diatoms, brown algae, synurophytes and other 'chrysophytes'

single celled, colonial and multicellular, free-living and parasitic

Chlorophylls a and c

VIRIDAEPLANTAE

The green algae, all but a few genera are algal, prasinophytes, chlorophyta (e.g. volvocalean algae, conjugatopohytes, Ulvales, Charales)

single celled, colonial and multicellular, free-living

Chlorophyll b

 

Genera of algal protists for which no clear ultrastructural identity has been developed (after Patterson, 1999):

Adinomonas

Archaeosphaerodiniopsis

Aurospora

Berghiella

Bjornbergiella

Boekelovia

Camptoptyche

Chalarodora

Chlamydomyxa

Copromonas

Cyanomastix

Dinoasteromonas

Dinoceras

Glaucocystopsis

Goniodinium

Heteromastix

Hillea

Histiophysis

Isoselmis

Melanodinium

Meringosphaera

Monodus

Nephrodinium

Pachydinium

Peliainia

Petasaria

Phialonema

Pleuromastix

Pseudoactiniscus

Strobilomonas

Syncrypta

Tetragonidium

Thaulirens

Thaumatodinium

Thylakomonas

Triangulomonas

 

  
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