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Are roughly A trillion species Microorganisms on Earth – most of which are bacteria.
Bacteria have a single cell. They do not have bones and are not like large animals that leave a clear signal in the geological records, which grateful peliytologists can study after several millions of years.
This has made it very difficult for scientists to establish the schedule of its early development. But with the help of machine learning, we are capable of filling many details. Our new research, Published in science todayIt also suggests that some bacteria have developed the ability to use oxygen when saturated about 2.4 billion years ago with the Earth.
A monumental event in the history of the Earth
About 4.5 billion years ago, the Moon was formed. Violence. A Mars-shaped object collided with the Earth, turning its surface into a melted rock. If life was present before this Holocaust, it was probably destroyed.
After that, the current ancestors of all living beings appeared: single-cell germs. For the first 80% of the history of life, the Earth was completely inhabited by these microbes.
In addition to the light of development in biology, evolutionary biologist Theodosius Dobzansky makes sense. Stated family In 1973. But how did the development of life move beyond the early history of the Earth?
Today we see that comparing DNA sequences with the amazing variety of life can tell us how different groups are related to each other. For example, we are more closely related to mushrooms than humans apple trees. Similarly, such comparison can tell us how different groups of bacteria belong to each other.
But comparison of DNA sequences can only be taken to us. DNA comparison does not say when evolutionary events took place in the history of the Earth. At one time, an organism reproduced two children. One of them gave birth to mushrooms, the other to humans (and many other species). But when did that creature live really? how many years ago?
One thing Geology teaches us that another monumental event exists in Earth’s history 2.4 billion years ago. At that time, the Earth’s atmosphere changed dramatically. A group of bacteria called cyanobacteria invented a trick that would change the story of life forever: photosynthesis.
Energy harvesting from the sun operated their cells. But it also produced an uncomfortable waste products, oxygen gas.
During millions of years, oxygen gradually accumulated in the atmosphere. Prior to this “great oxidation event”, there was almost no oxygen in the Earth, so life was not ready for it. In fact, for uninvited bacteria, oxygen is a poisonous gas, and so its release in the atmosphere probably caused a large -scale extinction. Living bacteria developed either to use oxygen, or retreated in the planet’s holiday where it is not to penetrate.
Bacterial tree of life
The great oxidation phenomenon is particularly interesting for us because not only because of its impact in the history of life, but also because it can be given a clear date. We know that it happened about 2.4 billion years ago – and we also know that most bacteria that were favorable to oxygen were to live after this incident. We used this information to layer on dates for the bacteria tree of life.
We started an artificial intelligence (AI) model to guess whether the bacteria live with oxygen or not, do not have genes. Many bacteria that we see today uses oxygen, such as cyanobacteria and others that live in the sea. But many people do not do, such as bacteria that live in our intestine.
As far as machine learning is used, it was quite straightforward. The chemical power of oxygen clearly replaces the genome of a bacteria because the metabolism of a cell is arranged around the use of oxygen, and therefore the data has many clues.
We then applied our machine learning model to guess which bacteria used oxygen in the past. This was possible because modern technologies not only allow us to guess how the species we see today is related, but also what genes are made in its genome.
A surprising turn
By using the planet-wide geological phenomenon of the great oxidation phenomenon as the “fossil” calibration point, our approach produced a wide timeline of bacterial development.
By combining the results from geology, peliytology, phytolonatics and machine learning, we were able to soften the time of bacterial development.
Our results also revealed a stunning turn: some bacterial lineages capable of using oxygen were present about 900 million years before the great oxidation event. This shows that these bacteria developed the ability to use oxygen, when atmospheric oxygen was rare.
Remandable, our findings indicated that Cyneobacteria actually developed the ability to use oxygen before developing photosynthesis.
This structure not only rebuilds our understanding of the evolutionary history of bacteria, but also shows how life’s abilities developed in response to the changing environment of the Earth.
(Author: Ben woodcroftAssociate Professor of Microbial Information Sciences, Quinamland University of Technology And Edran a. DevinPostDoctoral Fellow, Department of Biology, Swiss Federal Institute of Technology Zurich,
(Disclaimer statement: Ben Woodcroft receive funding from arch.
Adrian A. Dewin does not work for funding from any company or organization benefiting from this article, or receives this article, and will benefit from this article, and there is no relevant affiliation beyond their educational appointment.)
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