Date of endosymbiosis of a free-living cyanobacterium that led to primary plastids

Range 1,162 to 825 Mya
Organism Eukaryotes
Reference Douzery EJ, Snell EA, Bapteste E, Delsuc F, Philippe H. The timing of eukaryotic evolution: does a relaxed molecular clock reconcile proteins and fossils? Proc Natl Acad Sci U S A. 2004 Oct 26 101(43):15386-91 p.15388 right column top paragraphPubMed ID15494441
Method Researchers used a Bayesian relaxed molecular clock simultaneously calibrated by six paleontological constraints.
Comments "The relaxed molecular clock based on the 129 proteins was calibrated by six time constraints spread over the phylogenetic tree and defined within green plants, animals, and fungi. Credibility intervals at 95% indicated that the basal split between the major eukaryotic kingdoms documented here occurred 950–1,259 Mya (mean 1,085), followed by their diversification in 200 Myr (Fig. 1). Plantae originated 892–1,162 Mya (mean 1,010), and red algae branched off 825–1,061 Mya (mean 928), whereas stem land plants separated from green algae 662–812 Mya (mean 729). This suggests that the endosymbiosis of a free-living cyanobacterium that led to primary plastids (surrounded by two membranes) occurred between 825 and 1,162 Mya (Fig. 1). Plastids surrounded by four membranes originated from secondary endosymbiosis, in which a red alga was engulfed and retained by a flagellate protist. This event probably happened along the branch leading to stramenopiles + alveolates, i.e., between 767 and 1,072 Mya, shortly after the primary endosymbiosis (Fig. 1)" Mya=million years ago. For date of plastid endosymbiotic event of ~1 billion years ago see Kiefel 2006 PMID 17147999 p.159 2nd paragraph
Entered by Uri M
ID 107041