Environmental DNA Reveals a 2-Million-Year-Old Ecosystem in the Path of Climate Change

Overview

Using fragments of DNA bonded to minerals, scientists have been able to reconstruct a once-living landscape in northern Greenland from 2 million years ago. This reconstruction reveals an Ice Age ecosystem that was experiencing climate change at the time, which may provide insight into how to reduce current global warming. Environmental DNA from this remote period and location has been collected, analyzed, and interpreted to provide a "genetic roadmap" for how organisms can adapt to a warming climate. This week's cover of Nature features the project. At a news conference, six of the 40-person global team discussed the results.

Journal of Environmental Microbiology

An open-access journal called the Journal of Environmental Microbiology publishes articles with the goal of figuring out how particular gene mutations affect phenotypes and how to use that knowledge to create novel therapeutic strategies. This publication attempts to close the gap between the lab and healthcare facilities through the articles it publishes.

eDNA

Ancient and modern environments are both described using environmental DNA, or eDNA. The oldest known eDNA came from a mammoth that lived in Siberia one million years ago up until this point.

The eDNA used in the recent study was extracted from the Kap Kbenhavn Formation in Peary Land, North Greenland's "polar desert." Environmental DNA combines with fossilized plant material and preserved pollen to create images of former ecosystems. Cells are not home to the eDNA. DNA from mitochondria and chloroplasts, which is more plentiful than nuclear DNA because these organelles exist in numerous copies in a cell, is particularly resilient. Additionally, it is more likely to endure since it is more severely fragmented than DNA in a nucleus.

The Discovery Site

Each fragment of genetic material was only a millionth of a millimeter long, and the researchers retrieved 41 viable samples from clay and quartz at five sites.

The 20,000 years of sediment buildup in a shallow harbor covered the ancient DNA samples deeply. Geologist Kurt Kjaer from the University of Copenhagen said that the material was eventually stored in ice or permafrost and, significantly, was not disturbed by humans for two million years.

The approximately 400-foot-thick debris built up at the mouth of a fjord that jutted into the Arctic Ocean at the northernmost point of Greenland. When the earth was coming out of the Pleistocene Ice Age two to three million years ago, the temperature in Greenland briefly alternated between the Arctic and temperate zones.

Reading the eDNA Stories

The work was made feasible by three technological advances, according to Willerslev: learning how DNA bonds to mineral particles; developing a novel sequencing technology that can handle microscopic fragments of frayed DNA; and gathering the ancient genetic material. (A cool gadget that sounds like diet ice cream is the Arctic PaleoChip.)

An important role in the preservation was performed by the DNA-mineral interaction, which was examined by Karina Sand of the University of Copenhagen. Because DNA adheres strongly to minerals in marine environments, the enzymatic breakdown was inhibited. Although at different intensities than we were aware of, all the minerals in the formation could bind DNA.

In open seawater, DNA wouldn't have been able to bind to minerals, according to Sand. The researchers looked closely at contemporary DNA binding 

The Ancient Ecosystem's Flora and Fauna

A large jigsaw puzzle with only a few parts, the depiction of the ancient ecosystem was pieced together from fossils, preserved pollen, and DNA, especially from the resilient chloroplasts and mitochondria. A resolution wasn't great enough to distinguish between species, according to Pedersen, therefore the team was only able to identify 102 different types of plants, ranging from algae to trees, using these sparse cues. The nine animal species that were the most numerous at the time (to have left DNA) in the environment were also found, in addition to a large number of bacteria and fungi. He went on to say that the great majority of plants and animals are probably undetected because of their continuous (small) biomass. Poplars, red cedars, and firs are suggested by fossils and DNA from the southern portion of the region. "Plants were co-growing"

Setting the Scene

Up until the discovery of DNA, all that remained of an animal was a fragment of a tooth. Willerslev described how the team reacted to their discovery:

"We didn't notice much when we first arrived in the area in 2006 for a different project. With almost little life, it was comparable to the Sahara. Mosses and lichens were about it. So it was really amazing when we were able to retrieve the DNA and a totally new environment emerged. The existence of a forest had been recognized from macrofossils, but DNA revealed many more taxa.

Manuscript Submission

Each manuscript that is submitted is processed for an initial quality control check by the editorial office before going through the external peer review procedure. Preliminary quality control typically concludes in 7 days and focuses mostly on English, journal scope, and journal formatting.

Submission Link: https://www.pulsus.com/submissions/environmental-microbiology.html

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