Oct 17, 2022

What Chernobyl’s Black Frogs Reveal About Evolution

There seems to be no end to the fascinating truths that continue to emerge from the distinct ecosystem that exists in post-radiation-blast Chernobyl, and its black frogs are no exception.

In 1986, a massive and historic release of radioactive material was flung into the environment around Chernobyl. The impact was seen on every last bit of the surrounding area, living beings, plant life, you name it.

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Image Credit: iStock

Three decades later, Chernobyl is a nature preserve unlike any other in the world and is home to a diverse range of endangered species.

Radiation can damage genetic material and generate odd mutations, but we have also learned that it can spur adaptations in some species that allow them to live with it. It can be a very strong selective factor, favoring organisms with mechanisms that increase their survival in exactly these kids of scenarios.

One of those organisms seems to be the Eastern tree frog. In 2016, researchers spotted several black-tinted specimens, when their skin would normally have a bright green dorsal coloration.

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Image Credit: iNaturalist.org

A cool fact about melanin – which is a pigment responsible for the dark color of many organisms – is that it can reduce the negative effects of ultraviolet and ionizing radiation,

Its ability to absorb, dissipate, and neutralize ionized molecules can reduce the chances of cell damage and even an early death after radiation exposure.

Between 2017 and 2019, researchers observed the dorsal skin coloration of more than 200 male frogs found in different areas of northern Ukraine, all of which had varying levels of radiation exposure.

The results of those observations show that the frogs that live closer to Chernobyl have a much darker coloration than those from control areas further away. Some are actually pitch-black, though there is a range of colors and hues.

The darkest frogs were found in or near the most contaminated areas.

Researchers concluded that the frogs in Chernobyl at the time of the accident rapidly evolved in response to their massive exposure, with the darker colored frogs being selected due to their increased melanin.

More than 10 generations of frogs have been born since the accident but we rarely get to observe a natural selection event that happens so quickly.

That’s exactly what scientists believe is happening, though, due to the disproportionate number of dark-colored frogs in the Chernobyl Exclusion Zone.

This research will likely be used by scientists in other fields, such as nuclear waste management and even space exploration.

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