Why do some frogs fare better around chytrid than others?
Some species secrete anti-fungal chemicals, and some also have symbiotic bacteria living on their skin that also secrete anti-fungal chemicals. It appears that certain groups of frogs really don’t have very good protection against the disease. One group that I work with in Panama is Atelopus, or harlequin toads. They are very, very susceptible to the disease.
Why look at global populations rather than specific species?
The trouble with the amphibian chytrid story is that it is a lot of stories. For example, where I work in Panama is ground zero of amphibian declines from chytrid fungus. But perhaps in other areas of the world, their experience has not been as bad.
This study provides context and helps synthesize hundreds of thousands of hours of first-hand research all over the world so we can take stock of the cost of this disease. The first amphibian disappearances attributed to the chytrid fungus began in the 1970s. Peak declines appear to be around the early 1990s. We wanted to evaluate how severe the declines have been, and what animals we have lost on a global scale. Doing so paints a finer picture of where frogs are disappearing.
We speculated that this disease has been devastating, but now we have quantified it. We found that 90 frog species have gone extinct because of this pathogen, and more than 500 others are declining.
What are scientists doing to save frogs?
The good news is, there are some instances where frogs seem to be recovering. Initially, it was unclear as to whether the frogs were going to recover or evolve in some way. It appears that there are species across the phylogenetic tree that are seeing some recovery, and that is really encouraging. In fact, it is the basis of the next step we are taking in our research at the Smithsonian’s National Zoo.