Several studies have already revealed that wild dogs roaming near Chernobyl have several notable genetic characteristics. Intuitively, one might think that the continued high radiation levels in the exclusion zone are to blame — but a new study now suggests that these mutations are not linked to radioactivity.
The impact of the Chernobyl nuclear disaster, which flooded the region with radioactive emissions in 1986, no longer needs to be demonstrated. It is now estimated that this disaster is directly linked to thousands of cases of cancer and congenital malformations, not to mention the substantial damage to local flora and fauna. Even today, a exclusion zone of several thousand square kilometers still surrounds the region of Pripyat, the now abandoned town which was in the forefront on the day of the accident.
Almost 4 decades later, numerous studies have been carried out to determine the extent of ecological damage in this area which continues to be home to many animal species. Indeed, while humans quickly fled, scores of animals — some wild, some domestic — survived in the middle of the exclusion zone, and many of them were directly affected. by latent radioactivity.
The dogs of Chernobyl, a real genetic mystery
Among them, there are several hundred wild dogs, the direct descendants of those who were abandoned there by the population who hastily deserted the region 40 years earlier. These animals are the subject of particular interest among researchers, who see in them a unique opportunity to study how these populations adapted to this dramatic change in their environment.
In a study published last yearresearchers have for example identified significant genetic differences between a few hundred dogs who live in the exclusion zone and those who have taken up residence around ten kilometers further away.
Intuitively, one could consider that this is simply a consequence of mutations caused by radiation in the ancestors of these canids. But a recent new study, published this week in the journal PLOS One, suggests otherwise; according to its authors, there is no « no proof » that these differences are the result of a mutation rate boosted by the omnipresence of radiation.
To arrive at this conclusion, the researchers began by collecting samples of genetic material which they analyzed down to the smallest detail — first at the level of chromosomes, then at the level of the individual nucleotides that make up DNA. “It’s like using the zoom function on your phone camera to get more details: we start with an overview of a subject, then we zoom in,” says Matthew Breen, corresponding author of the study in a release from North Carolina State University.
Through these analyses, the team hoped in particular to find signs of radiation-induced mutations that could explain this genetic divergence. Indeed, even if more than 30 generations of wild dogs have succeeded one another in the region since the accident, the authors estimate that this type of mutation would probably still be detectable in the genome of these animals, especially if they had led to the the appearance of advantageous traits in terms of natural selection.
However, at the end of this rigorous analysis, the team did not not found the slightest proof that these dogs had undergone this kind of mutation! « The mutations do not appear to be the cause of the previously identified genetic differentiation between these two geographically close populations. », conclude the authors of the study.
A big ecological puzzle
In this case, how to explain this genetic divergence ? The authors suggest that the initial population of dogs may have been exposed to “ extreme selection pressure » at the time of the accident, and that it was their geographical separation from their congeners which then opened the way to these variations. But they also explain that it is still too early to formulate a rigorous conclusion. “ Investigating this issue is an important step that we are currently working on », Write the authors.
It will be very interesting to look at their conclusions, because the issues of this work go far beyond this population of dogs; it is only the tip of an immense ecological iceberg rich in lessons on the global impact of these disasters.
« The importance of continuing to study the environmental health aspects of large-scale disasters like this cannot be overstated. », insists Norman Kleiman, co-author of the study. “ It is certain that, given the rise of technology and the increasing industrialization of our societies, there will inevitably be more such disasters in the future, and we need to understand the potential health risks and the best way to protect populations ».
The text of the study is available ici.
Source: www.journaldugeek.com
