In April 1986, the Chernobyl nuclear power plant in Ukraine became the site of one of the most severe reactor meltdowns in history, prompting residents of the surrounding area to abandon their communities and, in many cases, their pets.
Nearly 40 years later, hundreds of stray dogs roam inside the Chernobyl Exclusion Zone (CEZ), an area encompassing some 1,000 square miles around the power plant where access is restricted due to radioactive and chemical fallout from the disaster. As feral descendents of pets that were left behind in the frenzied aftermath of the Chernobyl disaster, these dogs offer insights about the effects of contaminated environments on mammals, including humans.
Videos by VICE
Now, scientists have discovered hints that Chernobyl’s stray dogs may have adapted to their unusually toxic habitat on a core genetic level, a finding that could have implications for understanding the risks of chemical and radiation exposure on wildlife and people.
A team led by Megan Dillon, a PhD student at North Carolina State University, analyzed DNA obtained from two dog populations of Chernobyl: a group that lives in the immediate vicinity of the power plant, and another that lives near the partially abandoned city of Chernobyl, about 10 miles away from the plant.
The researchers “detected genetic evidence that suggests that these populations may have adapted to exposures faced over many generations,” which can help assess “how the impact of environmental catastrophes such as the Chernobyl nuclear disaster can influence animal populations,” according to a new study published in Canine Medicine and Genetics.
“Though Chernobyl wildlife has been the subject of previous ecological and genetic studies, little is known about the genetics of a population of over 500 dogs occupying the area surrounding the [Chernobyl Nuclear Power Plant] and Chernobyl City,” said Dillon and her colleagues in the study. “This dog population has expanded in the decades following the accident and is thought to be comprised at least partially of descendants of pets left behind during the chaotic evacuation in 1986.”
“In this scenario, it is intriguing to understand to what extent the descendants of these abandoned dogs have adapted to survive and sustain a growing population under these extreme environmental conditions,” the team continued. “Understanding and extending the genetic and health impacts of the exposure to both radiological and chemical insults in these dogs will strengthen the broader understanding of how these types of adverse environmental stressors can impact human health.”
Chernobyl’s feral dogs have attracted a lot of public attention and affection in recent years in the wake of several documentaries and articles about their lives in the contaminated wilds. But they have also become a hot topic for scientists who are interested in the long-term impacts of pollutants on ecosystems and human communities.
To probe the genetic backstories of these animals, Dillon and her colleagues analyzed blood samples drawn from a total of 116 unique dogs that were split almost evenly between the power plant and Chernobyl city populations. The samples were obtained in 2018 and 2019 as part of a vaccination and sterilization effort managed by the Clean Futures Fund Dogs of Chernobyl project.
The results revealed that there is very little interbreeding or gene flow between the two populations, despite their geographic proximity. Though both groups descended from a mixture of different domestic breeds, including the German Shepherd and the West Siberian Laika, they were noticeably genetically distinct from each other.
What’s more, the team found tantalizing hints that environmental stressors at Chernobyl may have produced some outlier genetic shifts, especially involving genes that aid in DNA repair, immune response, and other processes that might be associated with exposures from the meltdown fallout. The high levels of radiation at the site are among these environmental stressors, but other factors also include chemicals like heavy metals, organics, pesticides, and other pollutants that have contaminated the CEZ.
It will take more research to confirm whether these genes really do suggest that the stray dogs have genetically adapted to their surroundings over the years. To that end, Dillon and her colleagues plan to continue looking for clues about life in the fallout, along with other researchers who have made these dogs the focus of their work.
“As we explore the genomes of the dogs at this location, we aim to identify genome variants that were potentially induced by the prevailing multigenerational exposures and then subjected to ongoing selective pressures to maintain them in the population,” Dillon and her colleagues said in the study. “Our long-term goal with this unique population of dogs is to establish further evidence to evaluate the degree of local adaptation and thus develop measures of the impact of the exposures experienced by these dogs.”
“This work, and future studies with these canine populations, will advance our broader understanding on the genetic effects of prolonged exposures to both radiation and non-radiation toxic exposures, and the findings potentially more broadly applicable to the adverse health effects of other environmental nuclear and non-nuclear disasters in both animal and humans,” the team concluded.
