Wood frog tadpoles accelerate their growth and development when exposed to ranavirus, a deadly pathogen threatening amphibians worldwide, according to a new study published in Frontiers in Amphibian and Reptile Science. Researchers from Yale University discovered this survival strategy may help tadpoles either bolster immunity or flee infected ponds before the virus kills them.
The study, led by PhD student Logan Billet and senior author Dr. David Skelly, examined wood frog tadpoles (Rana sylvatica) in Connecticut ponds between 2021 and 2023. The team compared tadpole growth in three pond types: virus-free, partially infected, and outbreak ponds where all tadpoles died.
Key findings revealed that tadpoles in outbreak ponds initially grew faster and matured earlier, reaching larger sizes and advanced developmental stages (measured by the Gosner scale) within the first month. However, once mass mortality began, their growth stalled, leaving them smaller and less developed than their peers in safer ponds. In partially infected ponds, tadpoles also showed accelerated growth, suggesting a proactive response to viral threats.
“Accelerating growth early may help tadpoles strengthen immunity or escape to land sooner, reducing exposure,” explained Dr. Skelly. This plasticity could explain why some ponds experienced partial die-offs rather than total losses.
“We don’t yet know how tadpoles detect ranavirus—whether through chemical cues or other signals. Future experiments will explore this,” said Billet.
The study highlights amphibians’ remarkable adaptability to disease pressures, offering hope amid widespread declines fueled by ranavirus, habitat loss, and climate change. Further research could uncover ways to mitigate outbreaks and protect vulnerable species.
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