Author: Susan Milius / Source: Science News
The biggest genetic study yet of a notorious frog-killing fungus says it probably originated in East Asia in the 20th century.
The chytrid fungus nicknamed Bd, which attacks the skin, has astonished biologists in the last several decades by causing sudden, mass die-offs among frogs and other amphibians in Australia, Panama and other places worldwide. But where and when the killer emerged and how it spread have been a much-debated mystery. Studies have proposed North and South America as well as Africa and Asia as the homeland where a once-obscure fungus turned deadly.
Building up enough genetic data to untangle the origins has taken some 10 years of field and lab work at 37 institutions around the world, says infectious disease epidemiologist Simon O’Hanlon of Imperial College London. Analyzing the trove finds four main lineages of the fungus Batrachochytrium dendrobatidis and reveals that the worldwide killer group, BdGPL, probably originated 50 to 120 years ago, the researchers say.
How it traveled far and fast is less of a mystery. All the lineages show up in animals that have been traded internationally, often as exotic pets, the team reports in the May 11 Science.
That’s “one of the parts I found most worrisome,” says longtime Bd researcher Karen Lips of the University of Maryland in College Park, who was not involved in the new study.
International standards for pathogen monitoring are only as strong as their enforcement. “Here in the U.S. there is no requirement for testing of imports for chytrids,” she says.Very similar forms of the Bd fungus show up in places too far apart for the animals to have hopped, swum or crawled without human help. Suspicion falls on the international trade in amphibians. Lines color-coded for the four main lineages of the fungus link far-flung places…
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