As amphibian populations globally continue to be ravaged by chytridiomycosis, a disease caused by a deadly fungal pathogen, a new study suggests that some populations in Panama may have started becoming more resistant to the fungus about a decade after it began significantly impacting them. The results shed light on how species may recover from epidemics. More than a decade ago, a deadly fungal pathogen, Batrachochytrium dendrobatidis, drove amphibian population declines worldwide. These declines were well-studied in three sites in Panama, offering Jamie Voyles and colleagues an opportunity to conduct follow-up, post-epidemic analyses at these sites. The researchers resampled them. They report that nine of 12 species that were driven to critically low numbers have since recovered. More than 2,000 diagnostic samples (swabs of the amphibians' skin) reveal that the prevalence of B. dendrobatidis has decreased since the epidemics occurred. The researchers explored whether the fungus has become less pathogenic since the initial epidemics by comparing historic and contemporary strains of the fungus. They found that the modern strains of B. dendrobatidis do not grow at a different rate, nor do they affect immune cells from amphibians in a significantly different way than the earlier strains. Genetically, the historic and modern strains remain similar, too. Lastly, naïve frogs that were captured before the initial epidemic and raised in captivity were more susceptible to the fungus than their wild counterparts, the authors found. Therefore, they suggest that remaining amphibian populations in the area developed resistance to B. dendrobatidis. James P. Collins highlights this study in a related Perspective.
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Journal
Science