That the frog was an adult is also significant. "If he was a juvenile, you could say maybe he just beat the odds so far," Kolby said. "For it to be an adult and to be sitting in proximity to infection all around him really implies resistance."
Kolby suspects that a population of miles' robber frogs was already immune to the infection before it struck. Or perhaps the resistance later developed in individuals that had survived the initial outbreak of the fungus.
"It's kind of hard to say at this point," Kolby said.
Mike Sears, an ecologist at Southern Illinois University, called the news "very exciting indeed." But he added that it's still an open question as to how some frogs can survive amid Bd.
It could be that some species have evolved to be resistant, Sears said. Or it could be that some animals "use parts of the habitat which are not favorable to the growth of and infection by Bd, such as warmer and drier places."
Zoologist Karen Lips, of Southern Illinois University, said "I think its great that they found one."
"Hopefully there are others and they're reproducing. If we're lucky, [frogs] will really adapt and deal with this fungus," said Lips, who was not involved in the study.
Lips warns, however, against assuming that miles' robber frogs are now in the clear.
"Every time somebody finds a frog or something that hasn't been seen in quite some time, the media rushes to press and says it's not extinct," she said. "Well, it was never extinct. It was just really rare, and it's still really rare."
Unless the surviving population of miles' robber frogs is reasonably large and genetically diverse, the species is still in danger of vanishing completely, Lips said.
"You can hold out for a while, but you're really susceptible to random, chance events, such as a bad year of weather or a big outbreak of the disease again," she said.
"Bd never goes away. It's always there."
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