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As the climate warms, scientists have suggested that “time-traveling pathogens” released by the thawing of Arctic permafrost may pose a threat to modern ecosystems.
permafrost It is a solid layer of frozen ground made of soil, sand, and rock inside high latitude regions Such as Greenland, Alaska, Siberia, the Tibetan Plateau and northern Canada. New research finds that this layer of ice traps microbes that remain dormant for long periods of time, but a warming planet could create the right conditions for these pathogens to return from the past.
To better understand potential environmental influences, an international team of researchers numerically modeled the interactions between an ancient virus and modern bacteria in a study published July 27 in the journal Nature. PLOS Computational Biology.
Through tens of thousands of iterations, the study team tracked how the virus affected species diversity in the bacterial community. About 1% of ancient viruses cause major disruptions to digital ecosystems. The pathogen either increased diversity by up to 12% or, conversely, reduced species diversity by 32%. Not only did the viral invaders survive, they evolved over time, unbalancing the system.
The researchers used software called Avida to simulate whether pathogens would successfully penetrate an ecosystem. In a two-dimensional network, bacterial organisms interacted with their environment to compete for energy and space. Competitors who have found their niche can breed and survive through the tournaments.
In doing so, there were slight errors in reproduction that created genetic diversity, Which led to more complexity environmental system. When the virus entered this environment, like any other parasite, it was only able to obtain energy by filtering out suitable bacterial hosts. The hosts were then unable to receive the energy they needed to survive or reproduce, and subsequently died.
Does this mean that nearly a third of humans and other organisms are at risk of dying soon from an awakened viral disease? No. But lead author Giovanni Strona and co-author Cory Bradshaw said the findings add another layer of concern to the risks of an ever-warming climate.
In the past two decades, more research has been devoted to understanding the consequences thawing permafrost In arctic regions, such as A January 2022 NASA study that investigated the effects of carbon release during sudden thawing events and Jean-Michel Clavery’s decade-long look at infectious pathogens trapped in permafrost.
Claverie, professor emeritus of medicine and genomics at the Aix-Marseille University School of Medicine, revived what he called “zombie” viruses from permafrost in 2014 and 2015, and he and his team have reported five new families of ancient viruses capable of infecting amoebae in a study. In February, as previously reported by CNN. The research Clavery led demonstrated that ancient microbes can remain infectious despite being dormant for tens of thousands of years.
Using this assumption from Claverie’s work, Bradshaw, director of the Global Environment Laboratory at Flinders University in Australia, and Strona, senior researcher at the European Commission’s Joint Research Centre, designed a simulation to determine the consequences these pathogens could have.
And while 1% of pathogens causing a major disturbance seems low, 4 sextillion cells escape from the permafrost each year, Bradshaw said. This is much more than The number of stars in the galaxy.
“One percent in 4 sextillion is a number that most people can’t even conceive of. There are many, many chances for that to happen. The possibility is rare for one virus, but there are many possible viruses,” he told CNN in a phone interview.
Bradshaw likens permafrost viruses to any other invasive species. In the real world, most invasions fail, which the study reflected. He said the reason we still have problems with invasive species is because there are so many introductions to the ecosystem.
Read more: Invasive species around the world in pictures
Strona said that during the study’s successful invasion events, the resulting loss in species diversity of 32% does not mean that the virus killed a third of all bacteria in the digital ecosystem. Instead, it means that the entire ecosystem experienced a 32% loss in bacterial diversity.
When viruses infect bacteria and kill their hosts, the effects on the ecosystem are catastrophic. Resources that once existed in equilibrium weren’t available anymore, Bradshaw said, so the remaining species were forced into an arms race to survive. Predators and prey They fought for the use of resources that were left over, resulting in an unbalanced system. If there were fewer predators consuming the prey, the prey thrived, populated, and then used up more resources. Then overproduction reduced prey numbers in the natural culling process. If there were more predators, they would consume a lot more prey to survive, which leads to the same result.
The researchers found that the introduction of the virus was the sole cause of this large fluctuation in species diversity.
Modern organisms, including humans, have few, if any, natural defense mechanisms for ancient pathogens. For the research team, Strona and Bradshaw said, the study is more of a call to action than a real warning.
“We don’t need to sound the alarm right now,” said Dr. Kimberly Miner, a climate scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. She said she believes there are more pressing concerns about the climate crisis that could be more controllable, such as slowing the release of carbon into the atmosphere.
The study is a great first step in identifying risk from these unknown variants, said Miner, who was not involved in this research. But the possibility of infection from these emerging pathogens remains “highly unlikely”.
Areas containing Earth’s permafrost are sparsely populated. If the ancient pathogens somehow managed to escape, they would have a hard time finding people to infect. Furthermore, permafrost thaws gradually throughout the year at a rate of about 1.2 inches (3 centimeters) per season, and most of the 4-sextillion cells are released during this gradual thaw, Miner said.
She explained that the sudden thawing of the permafrost in the Arctic, which sometimes happens as quickly as possible for a few days, is “our biggest concern in terms of releasing organisms that we don’t know about.”
As the global average temperature increases, these sudden meltdowns will become more common. After record high temperatures in July, drone footage has captured Siberia’s largest crater engulfed in permafrost as ice thaws underground.
Strona and Bradshaw point out that more research is needed to extend the implications of their findings to humans or animals. The researchers said their intention was to provide a framework for assessing the risks of biological invaders from a bygone era.
In all of these cases, the study authors said, the only preventive measure — whether it’s sea level rise, deadly heat or emerging pathogens — is to slow or stop the carbon emissions that drive global warming and protect Arctic ecosystems. Without doing so, they said, environmental cascading would not be science fiction.
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