Revealed—the single event that made complex life possible in our oceans

December 1, 2015
A bacterial bloom. Credit: SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

The catalyst that allowed the evolution of complex life in Earth's oceans has been identified by a University of Bristol researcher. Up to 800 million years ago, the Earth's oceans were deprived of oxygen. It was only when microorganisms called phytoplankton, capable of performing photosynthesis, colonised the oceans – covering two thirds of our planet – that production of oxygen at a massive scale was made possible.

This major oxygenation event, driven by billions of tiny organisms in the , set the stage for a fundamental transformation of our planet – the evolution of as we know it today.

Our oceans became fully oxygenated at around 800 to 600 million years ago, when atmospheric oxygen reached modern concentrations. Crucially, this allowed for the evolution of animals and the beginning of our modern Earth System. It has long been known that cyanobacteria were the first microorganisms capable of producing oxygen. They did this through photosynthesis – a process that transforms energy from the sun into sugars and oxygen using carbon dioxide and water. Scientists have been trying to work out why it took so long for the Earth's atmosphere to reach modern concentrations of oxygen, when photosynthesis had already evolved by around 2,700 million years ago.

Patricia Sánchez-Baracaldo, Royal Society Research Fellow, from the School of Geographical Sciences at the University of Bristol, used genomic data to trace back the origin of these crucial and transformative marine planktonic cyanobacteria.

Her research, published in Scientific Reports, revealed that various different types of marine planktonic forms evolved relatively late – between 800 to 500 million years ago, arising from freshwater and/or marine benthic ancestors.

Early on, these cyanobacteria dominated only terrestrial and coastal environments, and with relatively low impact on the Earth's nutrient cycles. It was only when they properly colonised the oceans that the major, planet-altering event occurred.

Dr Sánchez-Baracaldo said: 'The results of this large-scale phylogenomic study imply that, early on, terrestrial cyanobacteria capable of building microbial mats dominated the ecology of the Early Earth'

'Rather surprisingly, marine planktonic cyanobacteria are relatively young, only evolving just prior to the origin of complex life – animals. By producing oxygen in vast quantities, these cyanobacteria enabled the development of complex life in our oceans. These biological events are linked - they help explain why it took so long for complex life to evolve on our planet. Cyanobacteria needed to colonise the oceans first',

'This study shows that several factors contributed to the delay of the oxygenation of the Earth's oceans. Firstly, cyanobacteria evolved in freshwater habitats and not in marine habitats as previously thought, and, second, marine productivity had a huge boost when cyanobacteria were finally able to colonise marine habitats; this allowed for the production of and carbon burial at unprecedented levels.'

'The genomic revolution has hugely improved our understanding of the tree of life of cyanobacteria. Without cyanobacteria, complex life on our planet as we know it simply would not have happened.' said Dr Sánchez-Baracaldo.

Explore further: Tracing cyanobacteria's tree of life in Earth's extreme environments

More information: Patricia Sánchez-Baracaldo. Origin of marine planktonic cyanobacteria, Scientific Reports (2015). DOI: 10.1038/srep17418

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WhoopdyDo
3 / 5 (2) Dec 01, 2015
So life formed in fresh water instead of salt?
Ojorf
5 / 5 (1) Dec 02, 2015
No WhoopdyDo, only "...cyanobacteria evolved in freshwater habitats and not in marine habitats as previously thought...".
This was long, long after life originally started.
WhoopdyDo
not rated yet Dec 02, 2015


No WhoopdyDo, only "...cyanobacteria evolved in freshwater habitats and not in marine habitats as previously thought...".
This was long, long after life originally started.


OK, clarification appreciated. But this leads to another question. Cyanobacteria form in salt water (maybe tidal pools) then evolve & adapt to fresh water, then evolve and adapt again to salt, where they finally become dominant enough to cause the Great Oxygenation? Whale evolution notwithstanding, it sounds like we fell off Occam's Razor somewhere. More reasonable to think the original saltwater cyanobacteria would simply have finally multiplied to the point where they produced the oxygen, right?

I followed the link, started in on the abstract and saw the genetic tree at http://www.nature...igures/1 but I admit I'm no scientist and couldn't follow it. Genomic data is generally solid evidence?
katesisco
not rated yet Dec 02, 2015
Most of these news releases require reading between the lines; here I think it is saying that surface cyanobacteria found the surface food--carbon d, dissolved minerals, etc sufficient to produce O2. Or we can suppose the sunlight was the cause.
If the planet was all ice, the bacteria in the ice would have colonized the melt full of minerals. Im going with sunlight on ice melt water.
viko_mx
1 / 5 (5) Dec 02, 2015
Аgain generalities of preschool level.

no specifics. no specifics. Evolutionists are not strong in the details. I have not met so far evolutionist, who can give an example of positive mutations or for natural physical process that leads to increased order (information) in one physical system.
thefurlong
5 / 5 (3) Dec 03, 2015
Аgain generalities of preschool level.

no specifics. no specifics. Evolutionists are not strong in the details. I have not met so far evolutionist, who can give an example of positive mutations

http://bigthink.c...n-humans
or for natural physical process that leads to increased order (information) in one physical system.

Snowflake formation. You begin with a random speck of dust. Then, ordered ice crystals form around it.
(to be continued)
thefurlong
5 / 5 (2) Dec 03, 2015
(continued)
In actuality, the laws of nature LEAD to order.

You have an incomplete understanding of information. It is the negative log of the probability of a configuration. If you lack constraints in your system (for example, an ideal gas), then, a high degree of information corresponds with an ordered state, because it is unlikely. However, if you have constraints, like the presence of gravity, then, your states are likelier to clump together under the mutual force of gravity. Hence, clumped, spherical states (states in hydrostatic equilibrium) are likelier than states without any sort of arrangement.

This tendency TOWARDS order in nature is further fueled by the laws of QM, in which only certain states are permitted, rather than a continuous spectrum, depending on temperature. Greater temperatures mean more room for things to arrange themselves randomly. Lower temperatures constrain these configurations, which means there are fewer types of possible configurations.
thefurlong
5 / 5 (2) Dec 03, 2015
I wrote
your states are likelier to clump together under the mutual force of gravity.

But I meant
MATTER IS likelier to clump together under the mutual force of gravity.
antialias_physorg
5 / 5 (3) Dec 03, 2015
increased order (information) in one physical system.

Erm...you are aware that increased order does not automatically mean increased information? Somehow from your 'arguments' over the past year I suspect you are missing this very basic bit of...information.

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