The Chernobyl exclusion zone has become an important center of study to understand how fauna adapts and evolves in the presence of ionizing radiation. Where it was believed that there would not be a trace of life, Germán Orizaola, in an article about the “fauna of Chernobyl 33 years after the nuclear accident”, highlights a “general absence of negative effects of radiation on animal and plant populations”, he points out: “We have also found some indication of adaptive responses to radiation, such as changes in the coloration of frogs. The frogs in the exclusion zone are darker, which could protect them from radiation”.
Researchers Germán Orizaola (University of Oviedo) and Pablo Burraco (Doñana Biological Station-CSIC) examined how exposure to radiation from the Chernobyl accident influences the dorsal skin coloration of male eastern San Antonio frogs (Hyla orientalis) sampled along a wide gradient of radioactive contamination in northern Ukraine.
They evaluated the relationship between the skin coloration of the frog (which can act as a protective mechanism against ionizing radiation), radiation conditions, and levels of oxidative stress. The skin coloration was darker in the localities closest to the areas with high levels of radiation at the time of the accident, while current radiation levels seemed not to influence the skin coloration in the San Antonio frogs in Chernobyl. The frogs living within the Chernobyl Exclusion Zone had a noticeably darker dorsal skin coloration than the frogs outside the Zone.
The maintenance of dark skin coloration was not related to physiological costs in terms of body condition or oxidative stress of individuals, and they did not detect short-term changes in the coloration of the frogs.
It is known that dark coloration protects against different sources of radiation by neutralizing free radicals and reducing DNA damage and, in particular, the presence of melanin has been proposed as a buffering mechanism against ionizing radiation. The results of this work suggest that exposure to high levels of ionizing radiation, probably at the time of the accident, may have benefited individuals with darker coloration in the arboreal frogs of Chernobyl. More studies are needed to determine the underlying mechanisms and evolutionary consequences of the patterns found by these researchers: Germán Orizaola and Pablo Burraco. (DOI: 10.1111/eva.13476).
