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Multiple secondary origins of the anaerobic lifestyle in eukaryotes

Lookup NU author(s): Emeritus Professor T. Martin Embley FMedSci FRSORCiD


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Classical ideas for early eukaryotic evolution often posited a period of anaerobic evolution producing a nucleated phagocytic cell to engulf the mitochondrial endosymbiont, whose presence allowed the host to colonize emerging aerobic environments. This idea was given credence by the existence of contemporary anaerobic eukaryotes that were thought to primitively lack mitochondria, thus providing examples of the type of host cell needed. However, the groups key to this hypothesis have now been shown to contain previously overlooked mitochondrial homologues called hydrogenosomes or mitosomes; organelles that share common ancestry with mitochondria but which do not carry out aerobic respiration. Mapping these data on the unfolding eukaryotic tree reveals that secondary adaptation to anaerobic habitats is a reoccurring theme among eukaryotes. The apparent ubiquity of mitochondrial homologues bears testament to the importance of the mitochondrial endosymbiosis, perhaps as a founding event, in eukaryotic evolution. Comparative study of different mitochondrial homologues is needed to determine their fundamental importance for contemporary eukaryotic cells.

Publication metadata

Author(s): Embley TM

Publication type: Article

Publication status: Published

Journal: Philosophical Transactions of the Royal Society of London B: Biological Sciences

Year: 2006

Volume: 361

Issue: 1470

Pages: 1055-1067

ISSN (print): 0962-8436

ISSN (electronic): 1471-2970

Publisher: The Royal Society Publishing


Notes: Journal Article Review