It’s been more than 40 years since the core meltdown of the Chornobyl nuclear reactor in what’s now Ukraine. Yet, its ramifications are still visible—not only in health problems for humans exposed to the radiation, but also in animal populations.
When people were evacuated from the Chornobyl Exclusion Zone (CEZ) in 1986, many had to leave their dogs behind. Later, efforts were made to eradicate what had become a wild population of radiation-exposed dogs, but some escaped detection. As such, several hundred dogs now roam the CEZ, offering a look at more than 30 generations of genomic response to radiation exposure and associated contamination.
Read more: “Chernobyl, 40 Years Later”
A study from 2023 found that these dogs were genetically different from those living 10 miles away in Chornobyl City, and a recent study published in the journal Genes delved deeper into the causes. “Are the genetic differences due to selection, or are they due to genetic drift over time in an isolated population?” asked lead author Megan Dillon, a veterinary researcher at North Carolina State University.
If the changes are from genetic drift, they should be random, with no relation to adaptations to the environment. If they’re from natural selection, they should favor genes for certain traits—in what’s called directional selection, for example in response to environmental stressors around Chornobyl. The CEZ is contaminated not only with radioactivity, but also with metals, organic compounds, pesticides, and asbestos.
Dillon and her coauthors compared the exposed dog population to three other unexposed feral dog populations in Chornobyl City, Eastern Europe, and the Galápagos Islands. The radiation-exposed dogs stood out genetically from all the others. In fact, the Chornobyl City dogs were actually more like canines in faraway Galápagos than those just 10 miles away in the CEZ.
An analysis of the CEZ genomes found evidence of directional selection in more than 100 genes. While there’s no way to be sure that the genetic changes weren’t from random drift, the results certainly point to adaptation. “When we dig deeper into those genomic regions, we find that these genes are involved in biologically relevant pathways that could allow them to overcome the effects of being exposed to toxicants in this environment,” added Dillon.
And so, despite the attempts to eliminate the pet dogs left behind in the CEZ, they’ve not only survived their new habitat but adapted to it as well.
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Lead Image: Sergiy Romanyuk
