Chernobyl frogs adapt to radiation by changing color

Higher levels of melanin turn Chernobyl tree frogs completely black – and also protect them from the harmful effects of radiation.

In 1986, a disaster struck Reactor 4 of the Chernobyl nuclear power plant, releasing an unprecedented amount of radioactive material that wreaked havoc on both the environment and the surrounding human population.

But more than three decades after the Chernobyl disaster, Phys.org reported, Chernobyl is one of the largest nature reserves in Europe, home to a diversity of endangered species including bears, wolves and lynx.

Scientists have also closely monitored animals in the area for reasons other than conservation. They are curious to know if any of the animals currently residing in Chernobyl have begun to adapt to radiation.

Now, a study may have found evidence of adaptation in tree frogs.

The study began in 2016, when researchers noticed that tree frogs in the area had developed an unusual black tint – a stark contrast to their typical bright green.

Germán Orizaola/Pablo Burraco, CC BYNew color adaptations found in eastern tree frogs at Chernobyl (left) contrast with the typical coloration of tree frogs (right).

By studying the color differences of tree frogs, Miami Herald reported, the researchers found that tree frogs living closer to Chernobyl’s historically high radiation areas had darker coloration.

It is important to note that the current radiation levels of a region did not determine a frog’s coloration – rather they were determined by the historical radiation levels.

“The dark coloration is typical of frogs within or near the most contaminated areas at the time of the accident,” the researchers wrote.

But why, exactly, do some Chernobyl frogs today have almost black skin? The answer lies in melanin, a dark pigment responsible for the darkening of many organisms, including humans and animals.

Less well known, however, is that melanin can also reduce the effects of ultraviolet radiation and ionizing radiation by absorbing and then dissipating the energy of the radiation.

Melanin can also bring together and neutralize ionized molecules inside a cell, which means that an organism affected by radiation is less likely to suffer cellular damage, thus increasing its chances of survival.

“The results of our study suggest that the Chernobyl frogs may have undergone a process of rapid evolution in response to radiation,” the researchers wrote. “In this scenario, frogs darker in color at the time of the accident, which normally represent a minority in their populations, would have been favored by the protective action of melanin.”

Germán Orizaola/Pablo Burraco, CC BY-SAColor gradations of eastern tree frogs found near Chernobyl.

Because darker-pigmented frogs had better protection against melanin, they were better adapted to survive radiation. These populations reproduced more successfully, as a result, in just 36 years – or 10 frog generations – natural selection favored darker-pigmented frogs.

The researchers also wrote that this study “is a first step to better understand the protective role of melanin in environments affected by radioactive contamination” and “opens the doors to promising applications in areas as diverse as waste management. nuclear weapons and space exploration“.

Unfortunately, research into the natural environment around Chernobyl has been suspended while Ukrainian forces defend against invading Russia, but researchers hope to be able to continue their work soon.

“We hope that the current war in Ukraine will soon end and that the international scientific community can return to study, together with our Ukrainian colleagues, the fascinating processes of evolution and regeneration of Chernobyl ecosystems,” they wrote.

After learning about the fascinating adaptations tree frogs have developed near Chernobyl, learn about the radiation-eating fungi that have also been found in the area. Then read the story of the man who set parts of Chernobyl on fire – and increased the radiation by 16 times.