Document Type
Article
Publication Date
8-16-2011
Publication Title
Proceedings of the National Academy of Sciences of the United States of America
Abstract
Although macroscopic plants, animals, and fungi are the most familiar eukaryotes, the bulk of eukaryotic diversity is microbial. Elucidating the timing of diversification among the more than 70 lineages is key to understanding the evolution of eukaryotes. Here, we use taxon-rich multigene data combined with diverse fossils and a relaxed molecular clock framework to estimate the timing of the last common ancestor of extant eukaryotes and the divergence of major clades. Overall, these analyses suggest that the last common ancestor lived between 1866 and 1679 Ma, consistent with the earliest microfossils interpreted with confidence as eukaryotic. During this interval, the Earth's surface differed markedly from today; for example, the oceans were incompletely ventilated, with ferruginous and, after about 1800 Ma, sulfidic water masses commonly lying beneath moderately oxygenated surface waters. Our time estimates also indicate that the major clades of eukaryotes diverged before 1000 Ma, with most or all probably diverging before 1200 Ma. Fossils, however, suggest that diversity within major extant clades expanded later, beginning about 800 Ma, when the oceans began their transition to a more modern chemical state. In combination, paleontological and molecular approaches indicate that long stems preceded diversification in the major eukaryotic lineages.
Keywords
Microbial eukaryotes, Origin of eukaryotes, Proterozoic oceans, Taxon sampling
Volume
108
Issue
33
First Page
13624
Last Page
13629
DOI
10.1073/pnas.1110633108
ISSN
00278424
Recommended Citation
Parfrey, Laura Wegener; Lahr, Daniel J.G.; Knoll, Andrew H.; and Katz, Laura A., "Estimating the Timing of Early Eukaryotic Diversification with Multigene Molecular Clocks" (2011). Biological Sciences: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/bio_facpubs/120
Comments
Archived as published.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. 1073/pnas.1110633108/-/DCSupplemental