Crown group Oxyphotobacteria postdate the rise of oxygen

Abstract

The rise of oxygen ca. 2.3 billion years ago (Ga) is the most distinct environmental transition in Earth history. This event was enabled by the evolution of oxygenic photosynthesis in the ancestors of Cyanobacteria. However, long-standing questions concern the evolutionary timing of this metabolism, with conflicting answers spanning more than one billion years. Recently, knowledge of the Cyanobacteria phylum has expanded with the discovery of non-photosynthetic members, including a closely related sister group termed Melainabacteria, with the known oxygenic phototrophs restricted to a clade recently designated Oxyphotobacteria. By integrating genomic data from the Melainabacteria, cross-calibrated Bayesian relaxed molecular clock analyses show that crown group Oxyphotobacteria evolved ca. 2.0 billion years ago (Ga), well after the rise of atmospheric dioxygen. We further estimate the divergence between Oxyphotobacteria and Melainabacteria ca. 2.5-2.6 Ga, which-if oxygenic photosynthesis is an evolutionary synapomorphy of the Oxyphotobacteria-marks an upper limit for the origin of oxygenic photosynthesis. Together, these results are consistent with the hypothesis that oxygenic photosynthesis evolved relatively close in time to the rise of oxygen.

Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis

“…DR3). As previously described (Shih et al, 2017), molecular clock analyses were estimated with the program BEAST2 (Drummond and Rambaut, 2007) using the CIPRES Science Gateway server (Miller et al, 2010 Note: Angiospermae and land plant age constraints from Smith et al (2010). Figure DR1.…”

Evolution of the 3-hydroxypropionate bicycle and recent transfer of anoxygenic photosynthesis into the Chloroflexi

“…The CpREV model was chosen as the best-fitting amino acid substitution model, based on ProtTest analysis (41). The concatenated amino acid sequences under the CpREV model and the 16S rDNA sequences under the GTR+G model in accordance with the 16S rDNA molecular clock study using BEAST as previously reported (2). For all runs, we ran two Markov chain Monte Carlo chains for 50 million generations, sampling every 10,000th generation, and discarding the first 50% of generations as burn-in.…”

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Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

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