Genetic signatures of directional selection found in Chornobyl dogs

A study published in the journal Genes indicates that the stray dog population near the Chornobyl Nuclear Power Plant (NPP) exhibits genetic signatures of directional selection rather than mutation (98). Researchers compared dogs living at the NPP with a separate population in Chornobyl City, located approximately 10 miles away (98). While both groups are geographically close, they show significant genetic differences (98). Specifically, dogs in Chornobyl City share genetic similarities with populations in Poland and Russia, whereas the NPP dogs possess distinct differences in regions associated with DNA repair (98).

The research sought to distinguish whether these differences were caused by directional selection or genetic drift, which involves random genetic changes that are not necessarily associated with fitness (98). To test this, the team compared the Chornobyl dogs to free-breeding dogs from Eastern Europe and an isolated population from the Galápagos Islands (98). The study found that the NPP population did not show the reduced genetic variation characteristic of genetic drift (98). Furthermore, while the Chornobyl City dogs were genetically similar to the Galápagos population, the NPP dogs were significantly different from them (98).

Genomic analysis of the NPP dogs identified more than 100 locations showing evidence of directional selection (98). These loci are associated with biological pathways including immune function, cell cycle functions, DNA replication, and DNA repair (98). These regions are also linked to the development of cancer (98).

Megan Dillon, a researcher at North Carolina State University, noted that these genomic signatures suggest the dogs may have pathways to overcome the effects of environmental toxicants (98). Matthew Breen, a professor at the same university, suggested that the environment might not have directly changed the genome; instead, individuals with specific existing genetic variants may have possessed a higher degree of fitness, allowing them to survive initial exposures (98).