DNA from 2-million-year-old sediment provides insight into ancient life in northern Greenland

DNA from 2-million-year-old sediment provides insight into ancient life in northern Greenland

NEW YORK – Ancient DNA extracted from sediments found in what is now a polar desert in northern Greenland suggests that the same site 2 million years ago was a more boreal environment with a range of vegetation and d animals like reindeer and mastodons.

In an analysis that spanned years, an international team of researchers isolated environmental DNA from clay and quartz samples taken from the Kap København Formation, a sediment deposit in far northern Greenland. These samples, dating back 2 million years, represent the oldest DNA samples today, surpassing the record by about 1 million years.

Eske Willerslev of the Universities of Copenhagen and Cambridge and her colleagues sequenced these ancient eDNA samples and compared them to reference genomes of modern plants and animals to piece together a picture of what lived in this region of Greenland when the climate was above 10 degrees. Celsius warmer than today. As they reported in Nature On Wednesday, they discovered an ecosystem unique to Earth today that combines elements of boreal and arctic climates and, surprisingly, was home to behemoths.

“It’s actually a very similar climate to what we expect on Earth due to global warming,” Willerslev said at a press briefing. “And so, of course, that kind of gives us an idea [of] how can nature react to rising temperatures?

The Kap København formation is at the mouth of a fjord and includes both clay and quartz sediments from marine and coastal environments. The researchers found that DNA could be preserved by binding to quartz and clay minerals in the sediment, although they were able to isolate more DNA that had been adsorbed to quartz.

In all, they extracted DNA from 41 different sediment samples from five different sites in the formation. After screening the samples for plastid DNA or mitochondrial DNA, the researchers sequenced them and compared their resulting sequences with datasets of modern animals, plants and microorganisms.

Through their analysis, the researchers discovered about 102 plant genera and nine different animal taxa. Because their samples were so old, researchers could often only resolve organisms to the level of family or genus, if at all. Willerslev noted that these taxa probably represent those that were most abundant in the region.

The samples still contained surprises. One of the animal taxa identified by the researchers was a mastodon, whose range was not known to extend into Greenland from its territory in North and Central America. Additionally, the researchers discovered DNA extracts from horseshoe crabs, which today typically live in warmer waters.

These findings begin to paint a picture of life in this place 2 million years ago, which researchers say has no modern analogue. Some plant taxa, such as spruce and poplar, suggest a boreal environment, while others reflect a more arctic environment.

Today, Willerslev said, this area is arid and home to moss, lichen and musk ox.

“So it was super exciting, when we got the DNA back, that a very, very different ecosystem emerged,” he noted.

A better understanding of the organisms that lived in northern Greenland 2 million years ago, when the climate was much warmer, could also inform efforts to protect modern organisms from the effects of climate change. The researchers added that while their data shows organisms in Greenland may have evolved and adapted to a warmer climate, climate change will occur at a much faster rate, giving organisms minimal time to adapt. .

According to the researchers, some organisms, especially plants, could be genetically modified to better resist these changes. “We have a genetic roadmap of how taxa respond to climate change,” Willerslev said, adding that this map could be applied to make taxa more resilient.

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