Evolution has always been based on the popular saying “if you can’t defeat the enemy, join him”. The nuclear accident that occurred in Chernobyl (Ukraine) in 1986 caused the biggest environmental disaster in the recent history of humanity, and since then many species have had to fight for their survival. The Darwinian mechanism of natural and evolutionary selection then kicked in, giving rise to one of the most striking phenomena science has encountered in recent years: It changes color to get rid of radiation.
Tree frogs were the protagonists of this study, conducted by Spaniards Pablo Burraco and Germán Orizaola from the Universities of Oviedo, Glasgow and Sweden, as well as from the Supreme Council for Scientific Research (CSIC).hyla oriental) from Chernobyl. According to the news published in the magazine Evolutionary Applications, These little jumping amphibians had to change their color to survive in harsh living conditions. The radioactive material leak had exposed them from one day to the next.
These animals often dye their skin a bright green, and while it is true that dark individuals may occasionally be found, the number of black frogs has increased exponentially near the areas most affected by the 1986 disaster.
In 2016, the research team identified the first black frogs. This prompted them to “examine the role of melanin coloration in the wild.” Between 2017 and 2019, researchers collected samples from more than 200 male samples from 12 different ponds in northern Ukraine. They included some of the most radioactive areas on the planet, as well as four areas outside the Chernobyl Exclusion Zone.
Melanin helps against radiation
The researchers hypothesized that darker skin tended to adapt better to radiation. It is a protection mechanism that provides It has to do with melanin. This substance absorbs and disperses some of the radiation energy. and at the same time, it can capture and neutralize ionized molecules inside the cell, such as reactive oxygen species. All these properties help organisms exposed to radiation to suffer less cell damage and therefore increase their chances of survival.
When the Chernobyl disaster occurred, dark frogs were in the minority. However, as time passes and concentrations of radioactive particles remain very high, black frogs were the most capable of surviving and reproducing.
More than ten frog belts have passed since the accident, and a classical process of natural selection, albeit very rapid, may explain why these dark specimens are the dominant species in the Chernobyl Exclusion Zone.
The scientists insist that their previous work has shown that this phenomenon is unrelated to current radiation levels. In fact, as the researchers describe, “this dark color is typical of frogs found in or near the most polluted areas at the time of the accident,” but The vivid colors of these animals return to normal as they move away from the exclusion zone.
Studying Chernobyl toads represents the first step towards better understanding the protective role of melanin in environments affected by radioactive contamination. It also opens the door to promising applications in various fields such as nuclear waste management and space exploration. It also shows that radiation is an important factor of natural selection.
Reference work: https://onlinelibrary.wiley.com/doi/pdf/10.1111/eva.13476
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