Timing the Origins of Multicellular Eukaryotes Through Phylogenomics and Relaxed Molecular Clock Analyses

  • Susan C. Sharpe*
  • Laura Eme*
  • Matthew W. Brown
  • Andrew J. RogerEmail author
Part of the Advances in Marine Genomics book series (AMGE, volume 2)


Multicellularity has evolved many times during eukaryote evolution. Deciphering the evolutionary transitions to multicellularity requires a robust deep phylogeny of eukaryotes to clarify the relationships amongst multicellular groups and determine their closest unicellular relatives. Here we review progress in understanding the phylogenetic relationships amongst multicellular and unicellular eukaryotes, as well as estimates of the ages of multicellular groups based on relaxed molecular clock (RMC) analyses. In addition, we present an RMC analysis of a large phylogenomic dataset to estimate the divergence dates of select major eukaryotic multicellular groups. Our analyses (and other recent studies) tentatively suggest that multicellular eukaryotes such as Metazoa, Fungi and two of the major multicellular red algal taxa first emerged in the mid-Neoproterozoic, whereas the dictyostelids arose in the Paleozoic. We also hypothesize that the first multicellular organisms emerged within 300–600 Myr after the Last Eukaryotic Common Ancestor. The age of land plants is less clear and is highly dependent on methodology, the genes analyzed, and the nature of fossil constraints. In general, there is great variability in all these age estimates, and their credible intervals frequently span hundreds of millions of years. These estimates are highly sensitive to both the models and methods of RMC analysis, as well as the manner in which fossil calibrations are treated in these analyses. As paleontological investigations continue to fill out the Proterozoic fossil record, genomic data is gathered from a greater diversity of eukaryotes and RMC methodology improves, we may converge on more precise estimates of the ages of multicellular eukaryotes that can be correlated with Earth’s ancient geochemical record.


Multicellularity Relaxed molecular clock Origins of complex multicellularity Bayesian framework Microfossils Eukaryote phylogeny 



This work and MWB’s postdoctoral fellowship were supported by a Discovery grant (227085-11) and an Accelerator grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) awarded to AJR. LE is supported by a Centre for Comparative Genomics and Evolutionary Bioinformatics postdoctoral fellowship from the Tula Foundation; SCS is supported by a graduate scholarships from NSERC and Killam trusts. AJR acknowledges the Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity and the Canada Research Chairs program. Computations were partially performed on the supercomputers at the SciNet HPC Consortium. SciNet is funded by the Canada Foundation for Innovation under the auspices of Compute Canada; the Government of Ontario; Ontario Research Fund—Research Excellence; and the University of Toronto (Loken et al. 2010).


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Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • Susan C. Sharpe*
    • 1
  • Laura Eme*
    • 1
  • Matthew W. Brown
    • 1
    • 2
  • Andrew J. Roger
    • 1
    Email author
  1. 1.Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular BiologyDalhousie UniversityHalifaxCanada
  2. 2.Department of Biological SciencesMississippi State UniversityMississippiUSA

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