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As you read this story, you will learn the following:
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For decades, scientists have studied animals living in or near the Chernobyl nuclear power plant to understand how increased radiation levels affect their health, growth and evolution.
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One study analyzed the DNA of 302 wild dogs living near a power plant, comparing the animals to other wild dogs living up to 10 miles away and found significant differences.
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While this study does not prove that radiation is responsible for these differences, the data provide an important first step in analyzing these irradiated populations and understanding how they compare to dogs living elsewhere.
On April 26, 1986, the Chernobyl nuclear reactor in northern Ukraine (then part of the Soviet Union) exploded, sending large amounts of radiation into the sky. Nearly four decades later, much of the Chernobyl nuclear power plant and surrounding area remains uninhabited—at least not by humans.
Animals of all kinds thrive in the absence of humans. Thousands of wild dogs live among the radio-resistant fauna, many of them descendants of pets left behind when the area was rapidly evacuated years ago. As the 40th anniversary of the world’s worst nuclear disaster approaches, biologists are now taking a closer look at animals located within the Chernobyl Exclusion Zone (CEZ), the size of Yosemite National Park, and studying how decades of radiation exposure can alter the animals’ genomes and perhaps even speed up evolution.
Scientists from the University of South Carolina and the National Human Genome Research Institute have begun examining the DNA of 302 wild dogs found in or around the CEZ to better understand how radiation altered their genomes. Their findings were published in the journal scientific progress 2023.
“Do they have mutations that allow them to live and reproduce successfully in this region?” co-author Elaine Ostrander, a dog genomics expert at the National Human Genome Research Institute, told us new york times. “What challenges do they face and how do they cope with their genetic challenges?”
The idea that radiation accelerates natural evolution is nothing new. For example, the practice of purposefully irradiating seeds in outer space to induce beneficial mutations is now a common approach to developing crops suitable for global warming.
For years, scientists have been analyzing certain animals that live in CEZs, including bacteria, rodents, and even birds. A 2016 study found that eastern tree frogs (Oriental Tree Frog) is usually green, but more commonly black within the CEZ. Biologists speculate that the frog’s melanin, the pigment responsible for skin color, underwent beneficial mutations that helped dissipate and neutralize some of the surrounding radiation.
This got scientists thinking: Could something similar happen to the wild dogs in Chernobyl?
The study found that wild dogs living near the Chernobyl power plant showed clear genetic differences from those living near the city of Chernobyl, 10 miles away. While this seems heavily suggestive that these dogs experienced some type of rapid mutation or evolution due to radiation exposure, this study is just the first step in proving this hypothesis.
However, one environmental scientist stated in an interview science newssaid these studies can be a tricky business, largely because it’s difficult to tease out radiation-induced mutations from other effects, such as inbreeding.
Since the original study was published, other researchers have delved into the issue and come up with competing results. In fact, a study published nearly two years later confidently asserts that we can cross radiation off the list of explanations for the current state of Chernobyl’s canine population. published in journal PLOS One The new genetic analysis, conducted by scientists at North Carolina State University and Columbia University Mailman School of Public Health in New York, looked at Chernobyl dogs at the chromosomal level, the genome level, and even the nucleotides and found no abnormalities that would suggest radiation-induced mutations.
To establish a baseline for comparison, the team compared the genomes of dogs from the city of Chernobyl, 10 miles from the CEZ, with those found in areas in Russia, Poland and other nearby countries. Once they determined that the populations were genetically similar, they used dogs from the city of Chernobyl as representative controls for the study. Of course, the task is no simple one, as dozens of generations of dogs have passed since the first puppies who witnessed the Chernobyl disaster in 1986.
“We know, for example, that exposure to high doses of radiation can cause downward instability at the chromosome level,” Matthew Breen, senior author of the study at North Carolina State University, said in a press statement. “Although these dogs are 30 or more generations older than those during the 1986 disaster, it is likely that the mutations would still be detectable if they conferred a survival advantage on those original dogs. But we did not find any such evidence in these dogs.”
Still, the 2023 study provides a template for further investigation into the effects of radiation on large mammals, as the DNA of dogs that roamed the Chernobyl power plant and nearby city of Chernobyl could be compared to dogs living in unirradiated areas. Although firm conclusions are currently lacking, this study once again shows that an area that was supposed to be a wasteland has become an unparalleled scientific opportunity to understand radiation and its impact on natural evolution.
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