EDGE Community


Project information

[Project name/title]
Saving the last mouth brooding frogs: is chytriomycosis driving Darwin’s frogs extinction?


[Project description/overview]
This project is investigating the enigmatic declines of the Darwin's frogs in Chile.


Location:
Central and Southern Chile.

Project type:
Scientific research

Relevant EDGE species:
Northern Darwin's Frog (Rhinoderma rufum)
Southern Darwin's frog (Rhinoderma darwinii)

Project members:
Claudio Soto-Azat




Relevant species
46. Northern Darwin's Frog (Rhinoderma rufum) CR

One of only two mouth-brooding frogs, it has not been seen since around 1980.

[Relevance description]
545. Southern Darwin's frog (Rhinoderma darwinii) VU

[Relevance description]
Aims
This project aims to evaluate the impact of chytridiomycosis on the Darwin's frogs in Chile, and to investigate possible other causes of the observed population declines.
 
Background

Chilean amphibians are characterized by a high degree of endemism. Nearly half of the 50 species are threatened by habitat destruction, contamination and more recently by disease. Some of these species are the Darwin’s frogs (Rhinderma darwinii, R. rufum) (both focal species in the EDGE Amphibian list), the Bullock's false toad (Telmatobufo bullocki) (EDGE #5), Barrio’s frog (Insuetophrynus acarpicus) (EDGE #23), Chile mountains false toad (Talmatobufo venustus) (EDGE #30), among others.

Rhinoderma rufum was recognised as a separate species in 1902. The behaviour that sets these frogs apart from all other amphibians in the world is that the males care for their young by incubating them in their vocal sacs for part of their development. There has been no sign of R. rufum since 1980 and the reasons for its abrupt disappearence remain poorly understood. For that reason I became an EDGE fellow trying to answer why these frogs are disapearing and evaluating the impact of chytridiomycosis on native ampghibians with special concern of Darwin´s frog, trough the project: “Saving the last mouth brooding frogs: is chytriomycosis driving Darwin’s frogs extinction?”

 
Project summary
There has been no sign of R. rufum since 1980 and the reasons for its apparent disappearance remain poorly understood. At the same time, there has been a constant disappearance of R. darwinii in northern populations, and in those places were the species used to be abundant, is no longer found. The current situation with R. rufum and R. darwinii is disconcertingly similar to the case of the gastric brooding frogs (Rheobatrachus sp.) of southern Australia. Like the mouth brooding Darwin’s frogs, there were just two species of gastric brooding frogs which experienced a rapid and enigmatic decline, suspected to have been caused by chytridiomycosis. Mirroring the elaborate parental care of the mouth brooders, female gastric brooding frogs swallowed their own eggs after laying, allowing them to develop in their stomachs. This phenomenal reproductive strategy disappeared over twenty years ago with the extinction of both species and may never evolve again.

Emerging infectious diseases (EIDs) have been reported increasingly as causes of death and population declines of free living wild animals. In most cases this emergence has been driven by direct human intervention, via host or parasite translocations (“pathogen pollution”), facilitated by the globalization of agriculture, commerce and human travel. These movements have been linked to the emergence of a series of diseases, such as West Nile virus in the Americas, squirrel poxvirus in the UK and avian malaria in Hawaii. Pathogen introductions may pose a significant threat to global biodiversity when disease is introduced into naïve populations.

Chytridiomycosis, a recently described emerging disease of amphibians caused by the non-hyphal zoosporic chytrid fungus Batrachochytrium dendrobatidis (Bd), has been implicated in epizootic amphibian mass mortalities on a global scale and amphibian extinctions in Australia, Central and South America. The simultaneous discovery of the pathogen in Panama and Australia, the wave-like spread and the catastrophic rate of population declines, all suggest that the fungus has been introduced into these areas from an area of enzootic infection elsewhere. In addition, genetic analyses of Bd isolates from Australia, Canada, USA, Panama and West Africa indicate that they are very highly conserved genetically. This implies that chytridiomycosis has been rapidly and recently globally spread.

To date, chytridiomycosis is known to infect over 200 species of anurans and caudates worldwide. Infected amphibians have been found in native populations, international trade for food, pet stores, ornamental pond stocking, zoos and laboratories. Fisher and Garner (2007) reported the infection in 28 species of introduced amphibians. Of these, the most widely distributed species, the African clawed frog (Xenopus laevis) have established feral populations in Europe, Australia, Asia and the Americas, including a significant population in the Central region of Chile. On the other hand, R. catesbeiana is extensively farmed as a food product and its international trade has grown exponentially in the last decades. This invasive species appear to be resistant to Bd infection. Such carriers of the infection have been demonstrated to transmit the pathogen to other, susceptible amphibian species, resulting in their mortality. This implies that these species may act as vectors of chytridiomycosis.

Chytrid infection have been found in native frogs of the families Bufonidae, Leptodactylae, Hylidae and Dendrobatidae from Ecuador, Brazil, Venezuela, Argentina and Colombia. Chilean batrachofauna characterizes for their high endemism of species. Of special interest are some anurans of the genus Telmatobius and Bufo inhabitants of high altitudes, genus which have been found to be chytrid positive in other South American countries. Also, the assessment of unique and critically endangered species of the genus Rhinoderma, Telmatobufo, Alsodes and Eupsophus, are extremely required. Our fervent hope is that the case of the gastric brooding frogs will not turn out to be ominously prophetic for the Darwin’s frogs; this project is a crucial step towards ensuring that history does not repeat itself. If R. rufum is already extinct a disproportionate amount of the planet’s unique evolutionary history and biodiversity has been lost forever and our responsibility will be to ensure the same does not happen for R. darwinii.
 
Timescales
Start date: February 2008
Duration: 4 years
Project members
Claudio Soto-Azat MV, MSc: Principal Investigator

Claudio is investigating the causes behind the enigmatic declines of the Rhinoderma Darwins frogs.

[Member role description]
Donors
Dirección De Investigación – Universidad Andres Bello
Wildlife Conservation Society
Zoological Society of London
 
[Title:] Southern Darwin's Frog
[Image caption]
Rhinoderma darwinii
[Title:] Disease Screening
[Image caption]
Claudio swabbing frogs
Associated Blog Posts
10th Aug 11
Clauidio Soto Azat EDGE fellow in the Darwin’s frog Project and Researcher at the Universidad Andrés Bello (UNAB) lead a rescue operation of four Darwin...  Read

18th Oct 10
A second update from EDGE Fellow Claudio Soto-Azat. Darwin’s frogs are two species of endangered anurans endemic to the native template beech forests of C...  Read

11th Oct 10
An update from EDGE Fellow Claudio Soto-Azat Darwin’s frogs (Rhinoderma darwinii and R. rufum) are two endangered amphibians species only known from the t...  Read

23rd Apr 10
In the last year, EDGE Fellow for the conservation of Darwin’s frogs, wildlife veterinarian, Claudio Soto, has undertaken several activities in order to kn...  Read

12th Apr 10
Today's Species of the Day is the Darwin's frog (Rhinoderma darwinii). This is one of our EDGE amphibian focal species, along with its only close relative, t...  Read

17th Dec 09
Intrepid frog fan and documentary-maker Lucy Cooke recently embarked upon a South American odyssey to document the curious lives of amphibians and highlight ...  Read

[Title:] Camouflage
[Image caption]
Darwin's frogs can blend in well with the native vegetation
[Title:] Camouflage
[Image caption]
The ventral patterns also aid camouflage
[Title:] Habitat
[Image caption]
Araucaria forest, central Chile
[Title:] Activities
[Image caption]
Expedition in search of R. rufum
[Title:] Project Leader
[Image caption]
Claudio Soto-Azat
[Title:] Southern Darwin's Frog
[Image caption]
Rhinoderma darwinii
[Title:] Northern Darwin's Frog
[Image caption]
Rhinoderma rufum has not been recorded since 1980
[Title:] Habitat
[Image caption]
Araucaria forest, central Chile
[Title:] Donor
[Image caption]
Universidad Andres Bello
[Title:] Donor
[Image caption]
Wildlife Conservation Society