Chernobyl radiation changed the color of the frogs  

Evolution in action

A new study focusing on Chernobyl frogs reveals evolution in action, as black frogs now vastly outnumber their green relatives. According to the study, the species Hyla orientalis which has this almost black skin due to increased melanin, was much more likely to survive the 1986 nuclear accident than frogs with lighter colored skin and this led to the predominance of their populations .

Radioactivity can damage the genetic material in living organisms and produce unwanted mutations. However, one of the most interesting topics in Chernobyl is trying to identify species that have evolved to live with the radioactivity. As with other pollutants, radioactivity can be a very powerful driver of natural selection, favoring organisms that possess mechanisms that will increase their survival in radioactively contaminated areas.

In the decades following the nuclear accident and the evacuation of people, the Chernobyl area has become a wildlife refuge. Studying more than 200 frogs inside the exclusion zone, the researchers found that 44% were darker than those outside the exclusion zone. But why is black skin favored in natural selection?

Melanin is known to protect against radiation because it can avoid the production of free radicals caused by direct exposure to radioactive particles in cells.

The cells of the lighter colored frogs were bombarded with higher amounts of radioactivity, which killed them at higher rates than their darker relatives, as the black frogs had a better chance of surviving the blast.

Melanin production can be more costly at a metabolic level, as we know is the case in many bird species. However, in frogs, its production does not seem to affect their physiology.

The research was published in Evolutionary Applications .