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Oxygen requirements of the earliest animals

Mills, Daniel B. and Ward, Lewis M. and Jones, CarriAyne and Sweeten, Brittany and Forth, Michael and Treusch, Alexander H. and Canfield, Donald E. (2014) Oxygen requirements of the earliest animals. Proceedings of the National Academy of Sciences of the United States of America, 111 (11). pp. 4168-4172. ISSN 0027-8424. PMCID PMC3964089.

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A rise in the oxygen content of the atmosphere and oceans is one of the most popular explanations for the relatively late and abrupt appearance of animal life on Earth. In this scenario, Earth’s surface environment failed to meet the high oxygen requirements of animals up until the middle to late Neoproterozoic Era (850–542 million years ago), when oxygen concentrations sufficiently rose to permit the existence of animal life for the first time. Although multiple lines of geochemical evidence support an oxygenation of the Ediacaran oceans (635–542 million years ago), roughly corresponding with the first appearance of metazoans in the fossil record, the oxygen requirements of basal animals remain unclear. Here we show that modern demosponges, serving as analogs for early animals, can survive under low-oxygen conditions of 0.5–4.0% present atmospheric levels. Because the last common ancestor of metazoans likely exhibited a physiology and morphology similar to that of a modern sponge, its oxygen demands may have been met well before the enhanced oxygenation of the Ediacaran Period. Therefore, the origin of animals may not have been triggered by a contemporaneous rise in the oxygen content of the atmosphere and oceans. Instead, other ecological and developmental processes are needed to adequately explain the origin and earliest evolution of animal life on Earth.

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URLURL TypeDescription CentralArticle InCommentary
Ward, Lewis M.0000-0002-9290-2567
Additional Information:© 2014 National Academy of Sciences. Freely available online through the PNAS open access option. Contributed by Donald E. Canfield, January 14, 2014 (sent for review August 26, 2013). We thank A. Glud for constructing and repairing the microelectrodes; D. Mathiesen, S. Ballo, and J. Laurenborg for collecting the sponges; and K. Lundgreen for technical support. We also acknowledge the very helpful comments of E. Sperling and N. Butterfield. Funding from the European Research Council (“Oxygen” Grant), the Danish National Research Foundation (Grant DNRF53), and the Agouron Institute supported this research. D.B.M. and L.M.W. contributed equally to this work. Author contributions: D.B.M., L.M.W., A.H.T., and D.E.C. designed research; D.B.M., L.M.W., C.J., B.S., and M.F. performed research; D.B.M., L.M.W., C.J., B.S., M.F., and D.E.C. analyzed data; and D.B.M., L.M.W., and D.E.C. wrote the paper. The authors declare no conflict of interest. This article contains supporting information online at
Funding AgencyGrant Number
European Research Council (ERC)UNSPECIFIED
Danish National Research FoundationDNRF53
Agouron InstituteUNSPECIFIED
Subject Keywords:hypoxia; Metazoa
Issue or Number:11
PubMed Central ID:PMC3964089
Record Number:CaltechAUTHORS:20140418-103100156
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Official Citation:Mills, D. B., Ward, L. M., Jones, C., Sweeten, B., Forth, M., Treusch, A. H., & Canfield, D. E. (2014). Oxygen requirements of the earliest animals. Proceedings of the National Academy of Sciences, 111(11), 4168-4172. doi: 10.1073/pnas.1400547111
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45051
Deposited By: Jason Perez
Deposited On:21 Apr 2014 14:47
Last Modified:03 Oct 2019 06:25

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