endosymbiotic

Examples of endosymbiotic in the following topics:

• Endosymbiosis and the Evolution of Eukaryotes

  • Endosymbiotic events probably contributed to the origin of the last common ancestor (LCA) of today's eukaryotes.
  • The endosymbiotic theory was first articulated by the Russian botanist Konstantin Mereschkowski in 1905.
  • Ivan Wallin extended the idea of an endosymbiotic origin to mitochondria in the 1920s.
  • The endosymbiotic theory was advanced and substantiated with microbiological evidence by Lynn Margulis in 1967 .
  • The possibility that the peroxisome organelles may have an endosymbiotic origin has also been considered, although they lack DNA.

• The Evolution of Plastids

  • Molecular and morphological evidence suggest that the chlorarachniophyte protists are derived from a secondary endosymbiotic event.
  • In fact, it appears that chlorarachniophytes are the products of a recent (on the scale of evolution) secondary endosymbiotic event.
  • The hypothesized process of endosymbiotic events leading to the evolution of chlorarachniophytes is shown.
  • In a primary endosymbiotic event, a heterotrophic eukaryote consumed a cyanobacterium.
  • In a secondary endosymbiotic event, the cell resulting from primary endosymbiosis was consumed by a second cell.

• Endosymbiotic Theory and the Evolution of Eukaryotes

  • Scientists believe the ultimate event in HGT (horizontal gene transfer) occurs through genome fusion between different species when two symbiotic organisms become endosymbiotic.
  • Using DNA analysis and a new mathematical algorithm called conditioned reconstruction (CR), it has been proposed that eukaryotic cells developed from an endosymbiotic gene fusion between two species: one an Archaea and the other a Bacteria.
  • An endosymbiotic fusion event would clearly explain this observation.
  • More recent work proposes that gram-negative bacteria, which are unique within their domain in that they contain two lipid bilayer membranes, did result from an endosymbiotic fusion of archaeal and bacterial species .
  • The theory that mitochondria and chloroplasts are endosymbiotic in origin is now widely accepted.

• Mitochondria

  • There are two hypotheses about the origin of mitochondria: endosymbiotic and autogenous, but the most accredited theory at present is endosymbiosis.
  • The endosymbiotic hypothesis suggests mitochondria were originally prokaryotic cells, capable of implementing oxidative mechanisms.

• Chromalveolata: Stramenopiles

  • Current evidence suggests that chromalveolates have an ancestor which resulted from a secondary endosymbiotic event.
  • This red algal cell had previously evolved chloroplasts from an endosymbiotic relationship with a photosynthetic prokaryote.

• Limitations to the Classic Model of Phylogenetic Trees

  • Finally, as an example of the ultimate gene transfer, theories of genome fusion between symbiotic or endosymbiotic organisms have been proposed to explain an event of great importance: the evolution of the first eukaryotic cell, without which humans could not have come into existence.

• Archaeplastida

  • Molecular evidence supports that all Archaeplastida are descendants of an endosymbiotic relationship between a heterotrophic protist and a cyanobacterium.

• Chromalveolata: Alveolates

  • Current evidence suggests that species classified as chromalveolates are derived from a common ancestor that engulfed a photosynthetic red algal cell, which itself had already evolved chloroplasts from an endosymbiotic relationship with a photosynthetic prokaryote.
  • Therefore, the ancestor of chromalveolates is believed to have resulted from a secondary endosymbiotic event.

• Genomic Similiarities between Distant Species

  • Finally, as an example of the ultimate gene transfer, theories of genome fusion between symbiotic or endosymbiotic organisms have been proposed to explain an event of great importance—the evolution of the first eukaryotic cell, without which humans could not have come into existence.

• The Evolution of Mitochondria

  • Several lines of evidence support the derivation of mitochondria from this endosymbiotic event.