Oldest DNA sheds light on a 2-million-year-old ecosystem that has no modern equivalent | CNN

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A core of Pleistocene sediments from northern Greenland has produced the world’s oldest DNA sequences.

2 million years old DNA samples It has revealed that the now lifeless polar region was once home to rich plant and animal life — including the elephant-like mammals known as mastodons, reindeer, hares, lemmings, geese, birch trees and poplars, according to new research published in the journal Nature on Wednesday.

The mixture of temperate and arctic trees and fauna suggested a previously unknown type of ecosystem that has no modern counterpart – One that could serve as a genetic road map The researchers found how different species might have adapted to the warmer climate.

The discovery is the work of scientists in Denmark who have been able to detect and recover environmental DNA – the genetic material that is dropped into the environment by all living things – in small amounts from sediment taken from the Copenhaven Formation, at the mouth of a fjord in the Arctic. The ocean at the northernmost point of Greenland, during an expedition in 2006. (Greenland is an autonomous state within Denmark).

Then they compared the DNA fragments with existing DNA libraries collected from extinct organisms Animals, plants and microorganisms. The genetic material has revealed dozens of plants and other creatures previously undiscovered at the site based on what is known from fossil records and pollen.

“The first thing that blew our minds when we looked at this data he is This mastodon and its presence are clearly far north, quite far north of what we would have known as its natural range,” study co-author Mikkel Pedersen, assistant professor at the University of Copenhagen’s Lundbeck Foundation GeoGenetics Center, said at a news conference.

It beat the previous record for world’s oldest DNA, set by research published last year on genetic material extracted from the teeth of mammoths that roamed the Siberian steppes more than a million years ago, as well as the previous record for DNA from sediments.

While DNA from animal bones or teeth can shed light on individual species, environmental DNA has enabled scientists to build up a picture of an entire ecosystem, said Professor Eske Willerslev, Fellow of St John’s College at the University of Cambridge and Director of the Lundbeck Foundation. GeoGenetics Center. In this case, the researchers found the reconstructed ecological community When temperatures range from 10 to 17 degrees Celsius Warmer than Greenland today.

“Only a few plant and animal fossils have been found in the area. It was very exciting when we got the DNA back (to see) that very different ecosystem. People knew from the large fossils that there were trees, some kind of forest there, but the DNA allowed us to by identifying many taxa (types of organisms),” said Willerslev, who led the research.

The researchers were surprised to find that cedars similar to those found in British Columbia today could have grown in the Arctic along with species like pine, which now grow in the far north of the planet. They haven’t found DNA from carnivores, but they believe predators — like bears, wolves, or even saber-toothed tigers — must have been present in the ecosystem.

Love Dalen, a professor at the Center for Paleogenetics at Stockholm University, who worked on the DNA research of mammoth teeth But he wasn’t involved in this study, he said the groundbreaking discovery really “pushed the envelope” of the ancient DNA field.

“This is a really cool paper!” he said via email. “It can tell us about the composition of ecosystems at different points in time, which is really important for understanding how past changes in climate affected biodiversity at the species level. This is something animal DNA can’t do.”

“Also, the findings that many temperate species (such as our spruce relatives and mastodons) live at such high altitudes are exceptionally interesting,” he added.

Close-up of organic material in the coastal sediments of the Cape Copenhaven Formation in northern Greenland.

Willerslev said the 16-year study was the longest project of its kind that he and most of his team of researchers have been involved in.

Extracting the bits of genetic code from the sediment took a great deal of scientific investigative work and many painstaking attempts – after the team demonstrated for the first time that DNA was hidden in the clay and quartz in the sediment and could be separated from it. The fact that the DNA attached to the metal surfaces was likely the reason it stayed so long, the researchers said.

“We revisited these samples and failed and failed. They called the lab the ‘damn of the Copenhaven Genesis,’” Willerslev said.

Further study of environmental DNA from this time period can help scientists understand the extent of the difference Living organisms may adapt to climate change.

“It’s a climate we expect to encounter on Earth due to global warming and it gives us an idea of ​​how nature will respond to rising temperatures,” he explained.

“If we can read this road map correctly, it really does hold the key to how organisms can[adapt]and how we can help organisms adapt to a rapidly changing climate.”

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