Early photosynthetic eukaryotes inhabited low salinity habitats

Patricia Sanchez-Baracaldo, John Raven , Davide Pisani, Andrew Knoll

Research output: Contribution to journalArticle (Academic Journal)peer-review

129 Citations (Scopus)
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Although it is widely accepted that the chrloroplasts in photosynthetic eukaryotes can be traced back to a single cyanobacterial ancestor, the nature of that ancestor remains debated. Chloroplasts have been proposed to derive from either early- or late-branching cyanobacterial lineages, and similarly, the timing and ecological setting of this event remain uncertain. Phylogenomic and Bayesian relaxed molecular clock analyses show that the chloroplast lineage branched deep within the cyanobacterial tree of life ∼2.1 billion y ago, and ancestral trait reconstruction places this event in low-salinity environments. The chloroplast took another 200 My to become established, with most extant groups originating much later. Our analyses help to illuminate the little known evolutionary history of early life on land.
Original languageEnglish
Pages (from-to)E7737-E7745
Number of pages9
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number37
Early online date14 Aug 2017
Publication statusPublished - 12 Sep 2017


  • Photosynthetic eukaryotes
  • chloroplast
  • cyanobacteria
  • Great Oxidation Event
  • Precambrian
  • primary endosymbiotic event
  • phylogenomics
  • relaxed molecular clock


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