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Reanalysis of global amphibian crisis study finds important flaws


Though biodiversity is in crisis globally, amphibians in particular face a variety of threats. One such threat comes from pathogens like the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). Bd causes chytridiomycosis, a disease that research indicates contributes to the decline of some amphibians. New research, however, now calls into question some prior evidence that links the widespread pathogen to hundreds of amphibian declines.

Last year in the journal Science, a research review by Scheele et al. concluded that Bd caused the decline of at least 501 amphibian species, of which 90 have gone extinct. That paper suggested that species losses due to Bd are “orders of magnitude greater than for other high-profile wildlife pathogens.” But a recent reanalysis led by Berkeley researchers found that Scheele et al.’s main conclusions lack evidence and are unreproducible.

In a Comment published in Science, the group conducting the reanalysis—including lead authors Max Lambert and Molly Womack, who are postdocs in the lab of professor Erica Rosenblum in the Department of Environmental Science, Policy, and Management (ESPM)—identified a number of data deficiencies and methodological issues in the Scheele et al. study. Working through the methods and datasets, they faced challenges in reproducing conclusions while identifying numerous instances of missing data. In some cases, data gaps failed to link Bd to species declines—even for many species which were previously reported with high certainty that Bd was the cause. MORE

Header image: Rana clamitans. Credit: Max Lambert.

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