A new study published in Nature this week has uncovered an extraordinary finding – a 2-million-year-old ecosystem in Greenland, revealed by environmental DNA. Researchers from institutions around the world, including Lawrence Livermore National Laboratory, have used the ancient DNA to map the ancient ecosystem, which weathered extreme climate change.
The 3.4 million old Fyles Leaf bed and Beaver Pond on Ellesmere Island in Arctic Canada preserve fossils of mammals that potentially could have colonized Greenland. To constrain the age of the sediment containing the environmental DNA, the researchers analyzed isotopes of beryllium and aluminum found in the soil, with LLNL’s Alan Hidy working on the age interpretation and modeling of that data.
“The DNA we collected is considerably older than any previously sequenced DNA,” Hidy said. “Our DNA results detected five times as many plant varieties as previous studies using shotgun sequencing of ancient sediments, which is well within the range of the richest northern boreal metabarcoding records.”
The higher temperatures likely caused the Greenland Ice Sheet to melt, possibly producing one of the last ice-free intervals in the last 2.4 million years. The research showed that the summer and winter average minimum temperatures of 10 degrees Celsius and 17 degrees C, respectively, were more than 10 degrees C warmer than present day.
The detection of both reindeer, caribou and mastodon calls for a revision of earlier paleoenvironmental reconstructions based on the site’s relatively impoverished faunal record, entailing both higher productivity and habitat diversity for much of the deposition period. All the vertebrate taxa identified by DNA are herbivores — caribou, geese, hares and rodents — and can all be abundant, at least seasonally, in boreal environments.
The authors concluded that the power of ancient eDNA adds “substantial detail to our knowledge of this unique, ancient open boreal forest community intermixed with Arctic species, a community composition that has no modern analogues.” Researchers hope the results could help to predict the long-term environmental toll of today’s global warming.
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