May 20th, 2009
Researchers find size really does matter in chytrid fungus battle
The invasive frog-killing pathogen chytrid fungus (Batrachochytrium dendrobatidis) kills some amphibians by compromising their growth rather than killing them directly, new research from Spain has found.
Trenton Garner, of the Zoological Society of London, and colleagues found that common toads (Alytes obstetricans) died after exposure to the chytrid fungus even when there was no detectable infection at the time of death.
The researchers concluded that multiple factors contributed to the death of the toads after they had been exposed to the fungus.
They found that tadpoles exposed to the fungus were smaller and less likely to survive their metamorphosis into adult toads.
They think it’s likely the tadpoles invested so much energy into fighting off fungus infection that their developmental processes were compromised, leading to death.
That survival of toads infected after metamorphosis depended on the animal’s body size. Those which survived the infection may act as reservoirs of chytrid fungus – a “situation which, in theory, has the potential to lead rapidly to host population extinction”.
The researchers warn that climate change may increase mortality rates among some amphibian populations by weakening their ability to withstand chytrid fungus infections, but say it could reduce the impact on other populations by making conditions less optimal for the fungus.
Garner TWJ, Walker S, Bosch J, Leech S, Rowcliffe JM, Cunningham AA, Fisher MC. 2009. LIfe history tradeoffs influence mortality associated with the amphibian pathogen Batrachochytrium denodrobatidis. Oikos 118: 783-791.