It is likely that the dark skin of the Chernobyl frogs allowed them to better tolerate radiation, made them more suitable for survival, and thus enabled them to produce more offspring, which is why they came to dominate all species in the Chernobyl area
More than 3 decades after the accident of the fourth reactor at the Chernobyl nuclear power plant in 1986, which resulted in the largest release of radioactive material in human history, and after a population displacement, the region has become a safe haven for a variety of endangered species, including bears and wolves Lynx, Chernobyl has become one of the largest nature reserves in Europe.
The radiation emitted by this accident was 400 times greater than the World War II bomb that exploded in Japanese Hiroshima, contaminating an area of 2,600 square kilometers and spreading across other parts of Europe, and despite the accident more than 35 years ago, the Chernobyl disaster continues to affect environment until today.
The effect of radiation exposure
Recently, a team of researchers presented the results of their study in a report published on The Conversation website on September 29. “Our work at Chernobyl began in 2016. By studying the effect of acute exposure to high doses of radiation on radiation-hit ecosystems at Chernobyl, in that year we discovered several unusually black oriental tree frogs near the damaged nuclear reactor, usually These species have a light green back colour.
Their study, published in the journal Evolutionary Applications, showed that the number of semi-black frogs of eastern tree frogs (Hyla orientalis) were more likely to survive the 1986 nuclear accident in Ukraine than light-skinned frogs, which led to the presence of large populations of frogs. Large dominated by dark frogs today.
"The Chernobyl accident released nearly 100 times the energy released by the nuclear bombs of Hiroshima and Nagasaki ," Pablo Buraco, lead author of the study and a biologist in Seville, Spain, told Live Science in an email.
The role of melanin in protection
Buraco and his team wanted to understand how nuclear radiation drove evolution in the animals that live there. "Radiation can destroy the genetic material of living organisms and generate unwanted mutations," the researchers wrote. "However, one of the most interesting research topics at Chernobyl is trying to discover whether some species are really adapted to live with radiation," the researchers wrote.
As with other pollutants, radiation can be a very strong selective agent, favoring organisms with mechanisms that increase their survival in areas contaminated with radioactive material.
The pigment melanin is known to be responsible for the dark color of many organisms, and its protective role can extend to ionizing radiation. This class of dyes can also reduce the negative effects of UV rays.
Melanin absorbs and dissipates part of the radiation energy, in addition, it can neutralize ionized molecules inside the cell, such as reactive oxygen species. These procedures make it less likely for individuals exposed to radiation to suffer cell damage, and increase their chances of survival.
Chernobyl frogs
After the first black frogs were discovered in 2016, researchers decided to study the role of melanin in preserving Chernobyl's wildlife. Between 2017 and 2019, they studied in detail the colors of eastern tree frogs in different regions of northern Ukraine.
During those years, they analyzed the back skin color of more than 200 captured male frogs at 12 different sites. These sites were distributed along a wide gradient of radioactive contamination, which included some of the most radioactive areas on the planet. For comparison, 4 sites outside the Chernobyl zone were studied, with their radiation levels measured for use as a control group.
Their research revealed that the color of the Chernobyl frogs is much darker than the color of frogs captured from outside the region. They also discovered that some of them are very black, and they found that this color is not related to the levels of radiation that the frogs are exposed to today, but the dark color was characteristic of the frogs from within or near the most polluted areas at the time of the accident.
Quick natural selection process
While Chernobyl is often associated with death and despair, the latest study revealed that this stricken city is where the evolution of life can be seen in practice, according to a report in The Weather Channel.
The results of the study indicate that Chernobyl frogs may have undergone a rapid evolution process in response to radiation due to some of them tolerating high radiation doses, and being able to survive.
In this scenario, those frogs that were dark in color at the time of the accident, usually a minority in their location, found the chance to survive after being irradiated, and continued to breed, occupying the area for the past three decades.
After considering all the facts and factors, the researchers were able to conclude that it is likely that the dark skin of the Chernobyl frogs allowed them to better tolerate radiation, made them more suitable for survival, and thus enabled them to produce more offspring, which is why they came to dominate all species in the Chernobyl zone.
The researchers also suggest that Chernobyl's frogs may have undergone a rapid evolutionary process in response to radiation, possibly due to an incredibly fast process of natural selection.
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