Years of radiation exposure made dogs of Chernobyl 'genetically distinct'

It’s been 37 years since the Chernobyl nuclear disaster, but there still exists dangerous levels of radiation in the abandoned city of Pripyat in Northern Ukraine.

While most of the humans were relocated and rehabilitated, the Chernobyl Nuclear Power Plant and its surrounding areas remain home to generations of dogs.

In a new study published in the peer-reviewed journal Science Advances, a team of researchers from the U.S., Poland, and Ukraine has conducted a rare genetic analysis of the canines living in and around radioactive environments.

The study claims that the dogs exposed to radioactivity are genetically distinct from dogs living farther away and other dogs in the world.

Studies conducted previously have shown that nuclear disasters have massive ecological consequences for wildlife and domestic animals. However, the levels of radiation at Chernobyl were unprecedented. Although the radiation levels have lowered over the years, its effects on the dog population, which has slowly reclaimed the area, still remains to be seen.

What does the study say?

First, a bit of background on how the genetic samples were collected.

It’s estimated that there are about 800 dogs currently residing in and around the Chernobyl Exclusion Zone. Owing to the increase in their numbers, the Chernobyl Dog Research Initiative (CDRI) was formed in 2017. This organization collected blood samples from 302 dogs and preserved them for further studies, including the one analyzed and published in Science Advances.

In the new study, the researchers have studied and analyzed the genetic structure of these 302 dogs, living at varying distances from the disaster site - Slavutych (45 km), Chernobyl City (15 km), and within the Chernobyl Nuclear Power Plant itself. This was done to capture the difference in radiation exposure based off of distance from the Chernobyl disaster site.

At first, it was believed by scientists that the dogs may have fraternized and bred so much that their genetic composition might have been the same. But that isn’t the case.

The study reveals that even though the dogs move between these three sites and breed freely, through their DNA, they could be distinguished from dogs living farther away. Although the researchers haven’t explicitly claimed radiation to be the cause of this genetic difference, this study can potentially help in further genomic studies.

The study also indicates that these dogs have existed in these areas for a long period of time, potentially since the disaster or even earlier.

It’s believed that most of these dogs were left behind by their owners when they were forced to evacuate the area. Back in 1986, the Ukrainian Ministry of Internal Affairs had initiated the culling of abandoned pets, but some dogs were believed to have evaded.

Study abstract:

The 1986 Chernobyl nuclear disaster initiated a series of catastrophic events resulting in long-term and widespread environmental contamination. We characterize the genetic structure of 302 dogs representing three free-roaming dog populations living within the power plant itself, as well as those 15 to 45 kilometers from the disaster site. Genome-wide profiles from Chernobyl, purebred and free-breeding dogs, worldwide reveal that the individuals from the power plant and Chernobyl City are genetically distinct, with the former displaying increased intrapopulation genetic similarity and differentiation. Analysis of shared ancestral genome segments highlights differences in the extent and timing of western breed introgression. Kinship analysis reveals 15 families, with the largest spanning all collection sites within the radioactive exclusion zone, reflecting migration of dogs between the power plant and Chernobyl City. This study presents the first characterization of a domestic species in Chernobyl, establishing their importance for genetic studies into the effects of exposure to long-term, low-dose ionizing radiation.