Article Review: Experimenting with the Past to Save the Future

    Since the 1970's, scientists have noticed deformations and an overall decline in amphibian populations. Nearly 40% of amphibian species have dwindled in number. This is a scary thought because amphibians are thought to be indicator species of overall environmental health. Amphibians have unique skin that allows for direct gas and chemical exchange with the surrounding environment. Their skin is very important for the most basic and fundamental mechanisms for survival. What is causing the increased declines???

                     (Bolitoglossa lincolni from San Marcos, Guatemala)


     The article I read, "Coincident Mass Extirpation of Neotropical Amphibians With the Emergence of the Infectious Fungal Pathogen Batrachochytrium dendrobatidis," by Tina Cheng, Sean Rovito, David Wake, and Vance Vredenburg, is about a graduate student (Cheng) and her colleagues using preserved specimens from museums and laboratories from the past 40 years to determine if the initial amphibian decline in the 1970's can be credited to the fungal pathogen, Batrachochytrium dendrobatidis (Bd), Like many amphibian declines are effected by today. Bd has been found to embed itself into the skin of amphibians causing the loss of skin function, osmoregulatory failure, and ultimately death.

(Bufo periglenes from Costa Rica's Monteverde Reserve: sudden extinction in the late 1980's)

     In this study, Cheng and others find a non-invasive molecular technique to detect Bd in preserved amphibian species that originated from two well documented areas in mesoamerica of mass amphibian decline to correlate whether Bd was the culprit of the sudden decrease in amphibian populations.
     I thought this was very interesting because you cannot always go back in time and investigate or experiment with extinct species or dead individuals. But by looking at the preserved species of these mesoamerican amphibian species over the particular time range of mass extinction rates, Cheng et at. were able to determine that 83% of the preserved specimens in fact tested positive for Bd. This provides direct evidence for the hypothesis that Bd played a major role in amphibian declines during the 1970's-1990's in Mexico and Guatemala and in Monteverde, Costa Rica. These findings give us a better understanding of the when and where Bd originated and emerged.
     In my personal opinion, the best way to begin helping endangered species or populations is to have a better understanding of the species itself. Learning more about Batrachochytrium dendrobatidis, which appears to play a major role in the threat of future amphibian population, is one of the first steps to begin helping and protecting the future of our beloved, and adorable amphibians.

For more information on this topic of the PNAS journal Volume 108 no.23 please see:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3111304/