Unusual evolution of tree frog populations in the Chernobyl exclusion zone

Area of Science:

• Ecology
• Evolutionary Biology
• Environmental Science

Background:

• Long-term ecological impacts of environmental pollutants, including radioactive contamination from the Chernobyl disaster, remain poorly understood.
• Few studies investigate the evolution of organisms chronically exposed to ionizing radiation within the Chernobyl exclusion zone.

Purpose of the Study:

• To investigate microevolutionary processes in Eastern tree frog (Hyla orientalis) populations in the Chernobyl region.
• To analyze genetic markers in 19 populations sampled approximately 30 years post-Chernobyl accident.

Main Methods:

• Genetic diversity was assessed using both nuclear and mitochondrial markers.
• Haplotype network analysis was employed to understand evolutionary history and mutation rates.

Main Results:

• Absence of genetic erosion and higher mitochondrial diversity were observed in Chernobyl's Eastern tree frogs compared to other European populations.
• Haplotype network analysis revealed a distinct, recent evolutionary history in Chernobyl's frogs, potentially driven by an elevated mutation rate.
• A model of haplotype network evolution suggested high mitochondrial mutation rates and small effective population sizes in Chernobyl's Eastern tree frogs.

Conclusions:

• Eastern tree frog populations in the Chernobyl exclusion zone exhibit unique evolutionary patterns and resilience, possibly due to large clutch sizes mitigating deleterious mutations.
• The findings raise concerns about the long-term effects of ionizing radiation on the evolutionary trajectory of other species inhabiting the Chernobyl exclusion zone.