Why can some toads survive a deadly fungus?
The mystery of why some populations of amphibians recover following outbreaks of a deadly fungus has been solved in a new study led by ZSL, UCL and Imperial College London.
The chytrid fungus, Batrachochytrium dendrobatidis (Bd), is a major cause of devastating declines in frogs and toads around the world - from tiny Darwin's frogs to giant mountain chicken frogs. Mass deaths occur often after amphibians transition out of the tadpole or larval stage and acquire the hard skin the fungus lives off. The new study, published in the journal Nature Chemical Biology, looked at common midwife toads living around four lakes in the Pyrenees in France and Spain whose populations had been ravaged by the fungus. Around one lake, the toads were dying in large numbers and nearly extinct, but around the other three lakes the populations had recovered, with Bd still present but causing fewer deaths. The team looked at antimicrobial chemicals called peptides that the toads secreted from their skin – a key part of their immune defence. They found that that these immune defences were much more likely to mature earlier, at the tadpole stage, among groups of toads that had recovered from Bd outbreaks, who were therefore better protected as they entered adulthood. Lead author Dr Phillip Jervis, of our Institute of Zoology, UCL Chemistry and Imperial College London, said: “Our study shows species that have declined heavily from this disease can still recover. They have the tools to fight off infection – it just depends on timing. The disease kills toads and frogs as they turn from tadpoles to adults. Getting mature immunity at the tadpole stage helps these toads survive and the population to continue..."
Read more: https://www.zsl.org/news-and-events/news/why-can-some-toads-survive-deadly-fungus
