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Integrated genomic and fossil evidence illuminates life’s early evolution and eukaryote origin

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)1556-1562
Number of pages7
JournalNature Ecology and Evolution
Volume2
Issue number10
Early online date20 Aug 2018
DOIs
DateAccepted/In press - 13 Jul 2018
DateE-pub ahead of print - 20 Aug 2018
DatePublished (current) - 1 Oct 2018

Abstract

Establishing a unified timescale for the early evolution of Earth and life is challenging and mired in controversy because of the paucity of fossil evidence, the difficulty of interpreting it and dispute over the deepest branching relationships in the tree of life. Surprisingly, it remains perhaps the only episode in the history of life where literal interpretations of the fossil record hold sway, revised with every new discovery and reinterpretation. We derive a timescale of life, combining a reappraisal of the fossil material with new molecular clock analyses. We find the last universal common ancestor of cellular life to have predated the end of late heavy bombardment (>3.9 billion years ago (Ga)). The crown clades of the two primary divisions of life, Eubacteria and Archaebacteria, emerged much later (<3.4 Ga), relegating the oldest fossil evidence for life to their stem lineages. The Great Oxidation Event significantly predates the origin of modern Cyanobacteria, indicating that oxygenic photosynthesis evolved within the cyanobacterial stem lineage. Modern eukaryotes do not constitute a primary lineage of life and emerged late in Earth’s history (<1.84 Ga), falsifying the hypothesis that the Great Oxidation Event facilitated their radiation. The symbiotic origin of mitochondria at 2.053–1.21 Ga reflects a late origin of the total-group Alphaproteobacteria to which the free living ancestor of mitochondria belonged.

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    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via Springer Nature at https://www.nature.com/articles/s41559-018-0644-x#Abs1. Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 861 KB, PDF-document

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