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The standard nucleomorph is the result of secondary endosymbiosis: a cyanobacterium first became the chloroplast of ancestral plants, which diverged into green and red algae among other groups; the algal cell is then captured by another eukaryote.
All other groups which have chloroplasts, besides the amoeboid genus Paulinella, have chloroplasts surrounded by three or four membranes, suggesting they were acquired secondarily from red or green algae. [note 1] Unlike red and green algae, glaucophytes have never been involved in secondary endosymbiosis events. [10]
Secondary endosymbiosis has occurred several times and has given rise to extremely diverse groups of algae and other eukaryotes. Some organisms can take opportunistic advantage of a similar process, where they engulf an alga and use the products of its photosynthesis, but once the prey item dies (or is lost) the host returns to a free living state.
Chloroplasts probably evolved following an endosymbiotic event between an ancestral, photosynthetic cyanobacterium and an early eukaryotic phagotroph. [17] This event (termed primary endosymbiosis) is at the origin of the red and green algae (including the land plants or Embryophytes which emerged within them) and the glaucophytes, which together make up the oldest evolutionary lineages of ...
The most largely studied tertiary plastids are found in dinoflagellates, where several independent tertiary endosymbiosis events have occurred. In the groups that contains a haplophyte plastid, these tertiary plastids are believed to have been derived from a red algae replacing secondary plastids. [15]
Guillardia is a genus of marine biflagellate cryptomonad algae with a plastid obtained through secondary endosymbiosis of a red alga. [1]Originally identified in Connecticut by Richard Guillard in the 1960s, Guillardia only has one described species. [2]
Before the discovery of the SAR supergroup, stramenopiles and alveolates were classified in the supergroup Chromalveolata alongside haptophytes and cryptomonads, being believed to have acquired plastids through secondary endosymbiosis of red algae through a common ancestor. [2] Meanwhile, Rhizaria was traditionally considered to be a separate ...
Chromalveolata was proposed to represent the organisms descended from a single secondary endosymbiosis involving a red alga and a bikont. [4] The plastids in these organisms are those that contain chlorophyll c. However, the monophyly of the Chromalveolata has been rejected.