Bacteria disappear at much higher rates than scientists ever anticipated

Bacteria disappear at rates much higher than those expected by scientists, according to a new study.

Between 45,000 and 95,000 types of bacteria have disappeared in the last millions of years.

But despite the high numbers, bacteria remain resistant to mass extinctions that have hit large life forms like dinosaurs, the researchers found.

Scientists used groundbreaking techniques to reveal that there are between 1.4 and 1.9 million bacterial lines.

They studied the mathematical structures found in DNA to pit the first evolutionary tree of bacteria – and reveal the extinction rate.

Dr. Stilianos Louca, Postdoctoral Fellow at the University of British Columbia The patterns of evolution and extinction of bacteria can reveal the "new ways" that simple organisms survive.

He explained, "For more than 3.5G yr (3.5 billion years), the geochemical composition of our planet has been shaped by the evolution and diversification of bacteria.

"The most important event of Oxygenation was caused by cyanobacteria about 2.35Gyrs ago. "Despite the predominant role of bacteria in ancient and modern biospheres, little is known about the dynamics by which their diversity has evolved over the course of the Earth's history."

He added: "Bacteria rarely fossilize, so we know very little about the evolution of the microbial landscape over time." Sequencing and math helped us to fill the bacterial tree, map their diversification and discover their extinctions.

"While modern bacterial diversity is undoubtedly high, it is only a tiny cliche of the diversity that evolution has generated during the history of the Earth."

In spite of the fact that bacteria have diversified exponentially without interruption.

And they avoid the abrupt and planetary mass extinctions that have occurred periodically in plants and animals.

Researchers suspect the competition between bacteria species cause high rate of microbial extinctions, leaving them less prone to sudden mass, multi-species extinctions.

Past speciation, which is the formation of new species, and extinction events leave a complex trace in phylogenies. Scientists have studied this code to reveal how bacteria have developed and evolved.

Co-author Professor Michael Doebeli, a zoologist and mathematician, said: "The study would not have been possible ten years ago.

"The Availability of Massive Sequencing Data

The researchers were faced with the challenge of accounting for the massive number of undiscovered bacterial species to build the tree.

They" used Sequencing data from 60 studies in Dr. Louca added: "Our results suggest that during the last 1Gyr [one billion years] overall rates of speciation and bacterial extinction were not significantly affected during of the last decade. "This conclusion does not support previous speculation that extinctions of plant and animal-associated bacteria – resulting from the extinction of their hosts – could significantly contribute to extinction rates. bacterial. "

Eukaryotic cells are those of animals, plants and fungi.

He concludes:" Our analysis highlights the diversity of bacteria "We have found evidence that overall bacterial diversity has increased mainly over the last 1Gyr, with globally constant rates of speciation and extinction or changing only slowly on average across all clades

". The conclusion has implications for how life has unfolded over the Earth's history, because bacteria is the oldest and most ubiquitous life form on Earth. "We estimate that global bacterial extinction rates are slightly lower than their speciation rates." This has important implications for the way we interpret records of ancient life. "

Scientists now plan to To study how the physiological properties of bacteria evolve over time

19659002] They hope to find out if their ecological diversity has also increased similarly to their taxonomic diversity.

The study is published in Ecology and evolution of nature