Frogs may be fighting against mass extinction

Frogs and up to 200 other species of amphibian are under severe threat from a pandemic which could wipe them out altogether. 

Batrachochytrium dendrobatidis (Bd), a form of chytrid fungus that causes a disease called Chytridiomycosis.

The condition is believed to have originated in Africa, but has now spread globally.

Atelopus varius was given its “varius” moniker because the species exhibits a wide range of colors and patterns. Photo by Brian Gratwicke, SCBI (c) Mongabay

Hope may be at hand, however, as a number of Panamanian frog species have shown resilience to the disease.

he African clawed frog (Xenopus laevis) is an aquatic frog species widely used in research. Photo by H. Krisp via Wikimedia Commons (CC BY SA 3.0) (c) Mongabay

A report, published by Mongabay, outlines the severity of the pandemic, but also highlights the resilience of the frogs in question;

“Chytridiomycosis is caused by Batrachochytrium dendrobatidis (Bd), a species from a group of fungi called chytrids. Members of this group are usually found on underwater decaying plant or animal matter, but Bd is different – it feeds on the skin of living amphibians, primarily frogs. Infection interferes with a frog’s ability to take in water and air through its skin, often leading to death.

Scientists believe Bd originated in Africa and first spread around the world due to the trade in African clawed frogs (Xenopus laevis), which are commonly used as laboratory research animals. American bullfrogs (Lithobates catesbeianus), which show low susceptibility to the disease and have become an invasive species in many parts of the world, have also been implicated as carriers. In addition, scientists detected Bd on bird feathers, opening up another wide route of transmission. Today, Bd is found on every continent where amphibians live.

Atelopus varius has several common names, including variable harlequin frog, clown frog, golden frog, painted frog and Veragoa stubfoot toad. Photo by Brian Gratwicke, SCBI (c) Mongabay

“This pathogen infects many different amphibian species — sometimes without causing disease — and can survive in the environment outside of its host, so it’s not going away anytime soon,” said Allison Byrne, a doctoral student at the University of California, Berkeley who is studying chytridiomycosis.

Infection can be devastating to frog populations, killing some off completely. In Australia alone, scientists believe the fungus was directly responsible for the extinction of four species. Worldwide, Bd has been implicated in the decline or extinction of at least 200 amphibian species, and some biologists peg it as the driving force behind the largest disease-caused loss of biodiversity ever recorded.

But there may be hope for frogs faced with Bd. A new study released yesterday in the journal Science finds populations of several frog species in Panama appear to be gaining resistance to the pathogen. The study was conducted by scientists at research institutions in the U.S. and Panama.

On Jan. 17, 2018, Smithsonian researchers released approximately 500 frogs at First Quantum Minerals’s concession site in Panama’s Colon province as a first step toward full-scale reintroduction of this species. This individual is carrying a radio transmitter so that it can be tracked by researchers after the release. Photo by Brian Gratwicke, SCBI (c) Mongabay

“In this study, we made the exciting discovery that a handful of amphibian species – some of which were thought to have been completely wiped out – are persisting, and may even be recovering, after lethal disease outbreaks,” study lead author Jamie Voyles, a disease ecologist at the University of Nevada, Reno, said in a statement. “We wanted to understand how it was happening. Was it a change in the pathogen, the frogs, or both?”

It is theorized that the pathogen has remained unchanged, but the frogs have, indeed, been adapting to deal with the condition. This signifies hope, not just for amphibians, but for a range of species, as new threats are constantly developing.

Colin J McCracken
Colin J McCracken

Director and Executive Editor

Colin J McCracken is an Irish editor and writer of both fiction and journalism. Coming from a background in education and film, his passions are split between the environmental and the entertaining. Constantly striving for a more sustainable existence and trying to balance it while simultaneously buying too many books.