Oxygen requirements of the earliest animals

In the paper

“Indeed, oxygen levels this high may have been reached as early as the Great Oxidation Event some 2.3-2.4 billion years ago (43,45) and may have persisted at these levels through much of the intervening time (43,44), with some likely swings to lower levels, however, around 1.8 billion years ago (46).”

What the sources say

• ?Not checked — no full text of the sourcecites [43] 43. Kump LR (2008) The rise of atmospheric oxygen. Nature 451(7176):277-278. source
• ?Not checked — no full text of the sourcecites [45] 45. Bekker A, Holland HD (2012) Oxygen overshoot and recovery during the early Pale- oproterozoic. Earth Planet Sci Lett 317-318:295-304. source
• ?Not checked — no full text of the sourcecites [44] 44. Canfield DE (2014) Proterozoic Atmospheric Oxygen. Treatise on Geochemistry, eds Holland HD, Turekian KK (Elsevier, Oxford), 2nd Ed., pp 197-216. source
• Partly supported

  The Significance section (page unavailable) places a rise in oxygen at the Great Oxidation Event about 2.3 billion years ago, followed by elevated levels for roughly 200 million years and then a collapse. The Results and Discussion section (page unavailable) describes later low-oxygen episodes, but the paper does not establish the cited 0.5–4% PAL range or its persistence through much of the intervening time. (LLM, conf=0.85)

  cites [46] 46. Canfield DE, et al. (2013) Oxygen dynamics in the aftermath of the Great Oxidation of Earth's atmosphere. Proc Natl Acad Sci USA 110(42):16736-16741. sourceExperimental — accuracy not yet measured

In the paper

“Indeed, according to present evidence, the earliest proposed signs of animals in the rock record (9,10), as well as molecular clock divergence estimates (11,12), predate the earliest evidence for deep ocean oxygenation (1), potentially by tens of millions of years.”

What the sources say

• ?Not checked — no full text of the sourcecites [9] 9. Love GD, et al. (2009) Fossil steroids record the appearance of Demospongiae during the Cryogenian period. Nature 457(7230):718-721. source
• ?Not checked — no full text of the sourcecites [10] 10. Maloof AC, et al. (2010) Possible animal-body fossils in pre-Marinoan limestones from South Australia. Nat Geosci 3(9):653-659. source
• Supported

  The Results (page unavailable) give molecular-clock estimates for early animal divergences: the minimum-evolution analysis dates the origin of Metazoa to 664 Ma and brackets eumetazoan evolution between 634 and 604 Ma. This paper supports the molecular-clock dates attributed to citations (11,12); the separate citation (1), not this paper, is offered for the timing of deep-ocean oxygenation. (LLM, conf=0.86)

  cites [11] 11. Peterson KJ, Butterfield NJ (2005) Origin of the Eumetazoa: Testing ecological pre- dictions of molecular clocks against the Proterozoic fossil record. Proc Natl Acad Sci USA 102(27):9547-9552. source
• ?Not checked — no full text of the sourcecites [12] 12. Erwin DH, et al. (2011) The Cambrian conundrum: Early divergence and later eco- logical success in the early history of animals. Science 334(6059):1091-1097. source
• ?Not checked — no full text of the sourcecites [1] 1. Sahoo SK, et al. (2012) Ocean oxygenation in the wake of the Marinoan glaciation. Nature 489(7417):546-549. source

In the paper

“We show that although sensitive to oxygen, H. panicea can both tolerate and grow at low oxygen levels from 0.5% to 4% PAL.”

• Also stated in: § Results and Discussion · plain

  “Overall, the sponges were able to both respire and feed to oxygen levels cycling between 0.5% and 4% PAL.”

In the paper

“functional gene and 16S rRNA analyses reveal a significant population of ammonium-oxidizing Archaea and betaproteobacteria, as well as other aerobic organisms (Fig. S6 and Table S1).”

In the paper

“Therefore, the majority of the oxygen uptake and Rhodomonas consumption observed during the experiments can be attributed to the sponges, with the background rates likely attributed to free-living microbes in our experimental system.”

In the paper

“Our results suggest that H. panicea is sensitive to both anoxia and prolonged exposure to relatively stagnant seawater.”

In the paper

“This K m is less than half of the 10% PAL serving as the estimated minimum level of atmospheric oxygen thought to have permitted the oxygenation of the deep oceans around 580 Ma (2), as well as the level estimated to permit the existence of millimeter-width, diffusionlimited animals (15).”

What the sources say

• ?Not checked — no full text of the sourcecites [2] 2. Canfield DE, Poulton SW, Narbonne GM (2007) Late-Neoproterozoic deep-ocean oxygenation and the rise of animal life. Science 315(5808):92-95. source
• ?Not checked — no full text of the sourcecites [15] 15. Catling DC, Glein CR, Zahnle KJ, McKay CP (2005) Why O2 is required by complex life on habitable planets and the concept of planetary "oxygenation time" Astrobiology 5(3):415-438. source

In the paper

“Although levels of atmospheric oxygen may have reached 10% PAL by 580 Ma, the geochemical record does not preclude oxygen levels of 0.5-4% PAL during the Cryogenian Period (43,44).”

What the sources say

• ?Not checked — no full text of the sourcecites [43] 43. Kump LR (2008) The rise of atmospheric oxygen. Nature 451(7176):277-278. source
• ?Not checked — no full text of the sourcecites [44] 44. Canfield DE (2014) Proterozoic Atmospheric Oxygen. Treatise on Geochemistry, eds Holland HD, Turekian KK (Elsevier, Oxford), 2nd Ed., pp 197-216. source

In the paper

“Such evidence can reasonably be obtained by studying modern animals that resemble the earliest metazoans.”

In the paper

“Given the complete absence of necrosis in the sponges maintained at both low and high oxygen levels during this run, the necrosis observed during experiment 1 was likely due to the infrequent exchange of fresh seawater and not necessarily the low oxygen levels.”

In the paper

“This suggests that although 3-4% PAL oxygen may not compromise H. panicea's growth or maintenance of healthy tissue, anoxia still does.”

In the paper

“This suggests that the similarities between choanocytes and choanoflagellates were inherited from a common ancestor and that the choanocytebased feeding mode, as retained by sponges, is likely ancestral to all animals (29).”

What the sources say

• ?Not checked — no full text of the sourcecites [29] 29. Nichols SA, Dayel MJ, King N (2009) Genomic, phylogenetic, and cell biological in- sights into metazoan origins. Animal Evolution: Genes, Genomes, Fossils and Trees, eds Telford MJ, Littlewood DTJ (Oxford University Press, Oxford), pp 24-32. source

In the paper

“Furthermore, to establish that low levels of atmospheric oxygen, in fact, delayed the origin of animal life on Earth, it is necessary to know the minimum oxygen requirements of early animals.”

In the paper

“Therefore, to more conclusively determine the minimum oxygen requirements of metazoans, direct experimental evidence is required.”

In the paper

“LMA sponges are known to have shorter and wider water canals (38), as well as larger choanoflagellate chambers (39), than high-microbial abundance (HMA) sponges.”

What the sources say

• ?Not checked — no full text of the sourcecites [38] 38. Vacelet J, Donadey C (1977) Electron-microscope study of association between some sponges and bacteria. J Exp Mar Biol Ecol 30(3):301-314. source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [39] 39. Boury-Esnault N, de Vos L, Donadey C, Vacelet J (1990) Ultrastructure of Choanosome and Sponge Classification (Smithsonian Institution Press, Washington, DC), pp 237-244.

In the paper

“Under this scenario, the origin of animal life was not a response to atmospheric oxygenation but part of the ecological reworking of marine biogeochemical cycles.”

In the paper

“Recent molecular clock estimates place the last common ancestor of all sponges at nearly 800 Ma (12), whereas putative sponge-like body fossils are found in rocks dated between 660 and 635 Ma (10) in the Cryogenian Period (850-635 Ma).”

What the sources say

• ?Not checked — no full text of the sourcecites [12] 12. Erwin DH, et al. (2011) The Cambrian conundrum: Early divergence and later eco- logical success in the early history of animals. Science 334(6059):1091-1097. source
• ?Not checked — no full text of the sourcecites [10] 10. Maloof AC, et al. (2010) Possible animal-body fossils in pre-Marinoan limestones from South Australia. Nat Geosci 3(9):653-659. source

In the paper

“We provide experimental evidence suggesting that the last common ancestor of animals could have thrived in oxygen levels as low as 0.5% to 4% of present atmospheric levels, which were likely met on Earth well before animals evolved.”