Century-Old Fish Transfer Reveals Rapid Metabolic Evolution in Alpine Lakes

In 1924, conservationists moved Arctic charr from Lake Geneva to the high-altitude Lake Allos in France's Mercantour National Park. A century later, a team from Université Savoie Mont Blanc-INRAE compared adult fish from both lakes, noting clear differences in morphology and growth that reflected local environmental conditions. To separate environmental effects from genetic change, they bred the fish and raised the juveniles under identical laboratory settings.

Even in this controlled environment, the Lake Allos lineage maintained a faster metabolism and a distinct heat-stress response, pointing to rapid genetic adaptation. The researchers conclude that while many physical differences stem from phenotypic plasticity, metabolic traits can evolve quickly when populations become isolated. These results have implications for conserving cold-water species as European lakes warm, highlighting the potential for swift evolutionary responses to climate change.