For generations of dogs, home is the radioactive remains of the Chernobyl nuclear power plant.
In the first genetic analysis of these animals, scientists found that dogs living in the industrial area of the power plant are genetically distinct from dogs living further away.
Although the team was able to distinguish between dog populations, the researchers did not identify radiation as the reason for any genetic differences. But future studies that build on the findings, reported March 3 in scientific advances, can help uncover how radioactive environments leave their mark on animal genomes.
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This could have implications for other nuclear disasters and even human space travel, says Timothy Mousseau, an evolutionary ecologist at the University of South Carolina at Columbia. “We have high hopes that what we learn from these dogs… will be useful in understanding human exposures in the future,” he says.
Since his first trip in 1999, Mousseau has lost count of the number of times he has been to Chernobyl. “I lost track after hitting about 50 visits.”
He first encountered Chernobyl’s semi-wild dogs in 2017, while on a trip with the Clean Futures Fund+, an organization that provides veterinary care for animals. Not much is known about how the local dogs survived after the nuclear accident. In 1986, an explosion in one of the power plant’s reactors triggered a disaster that released large amounts of radioactive isotopes into the air. Contamination from the plant’s radioactive cloud has largely taken hold nearby, in an area now called the Chernobyl Exclusion Zone.
The dogs have been living in the area since the disaster, fed by Chernobyl cleanup workers and tourists. Some 250 wanderers lived in and around the plant, among the spent fuel processing facilities and in the shadow of the crumbling reactor. Hundreds more wander further into the Exclusion Zone, an area the size of Yosemite National Park.
During Mousseau’s visits, his team took blood samples from these dogs for DNA analysis, which allowed researchers to map the dogs’ complex family structures. “We know who’s related to whom,” says Elaine Ostrander, a geneticist at the National Human Genome Research Institute in Bethesda, Maryland. “We know their heritage.”
Canine packs aren’t just a hodgepodge of wild dogs, she says. “There are actually families of dogs that raise, live, exist in the powerhouse,” she says. “Who would have imagined?
Exclusion Zone dogs share ancestry with German Shepherds and other herding breeds, like many other Eastern European free-breeding dogs, the team reports. And although their work revealed that dogs in the area of the power plant appear genetically different from dogs in the city of Chernobyl, about 15 kilometers away, the team does not know whether the radiation caused these differences or not. , says Ostrander. Dogs can be genetically distinct simply because they live in a relatively isolated area.
The new discovery isn’t all that surprising, says Jim Smith, an environmental scientist at the University of Portsmouth in England. He was not part of the new study but has been working in this field for decades. He worries that people will assume “that the radiation has something to do with it,” he says. But “there is no evidence of this”.
Scientists are trying to figure out how radiation exposure at Chernobyl affected wildlife for decades (SN: 02/05/14). “We looked at the consequences for birds, rodents, bacteria and plants,” Mousseau says. His team found animals with high mutation rates, shortened lifespans and early cataracts.
It’s not easy to disentangle the effects of low-dose radiation among other factors, Smith says. “[These studies] are so difficult…there are many other things going on in the natural environment. Additionally, animals may derive some benefit when humans leave contaminated areas, he says.
How, or if, radiation damage accumulates in dogs’ genomes is something the team is now studying, Ostrander says. Knowing the genetic background of dogs will make it easier to spot radiation warning signals, says Bridgett vonHoldt, an evolutionary geneticist at Princeton University, who was not involved in the work.
“I feel like it’s a cliffhanger,” she says. “I want to know more.”