Using genetic tools to understand and manage chytridiomycosis

Lowland leopard frog (Lithobates yavapaiensis)

The lowland leopard frog is the focus of SCBI postdoc Anna Savage's work looking at the relationship between genes and chytrid resistance.

Chytridiomycosis, the disease wiping out frog species around the world, was described in 1999 by a team of researchers at the Smithsonian and the University of Maine. Today, in addition to creating an insurance population for various Panamanian species, the Smithsonian Conservation Biology Institute aims to find a way to manage this disease. One of the most promising solutions to stopping the killer may rest in genetics. SCBI scientists are looking to identify genes within frogs that provide resistance to the pathogen or that make them more susceptible to it.

Researchers pursuing this approach are optimistic that genetics could provide different answers than those offered by probiotics, which SCBI is also pursuing. The genetic approach is one based on natural selection.

“If you look across species, including humans, diseases rarely wipe out an entire species without any evidence of resistance, regardless of how virulent they are,” said Anna Savage, an postdoctoral fellow in SCBI’s Center for Conservation and Evolutionary Genetics studying the genetics of chytrid. “Immune systems are so complex that there’s a strong possibility for the development of resistance. The probability that a species develops no resistance to a disease is rather small.”

Genetics research within the last decade has identified frogs with varying degrees of resistance to chytrid. Savage is focusing her research on the lowland leopard frog (Lithobates yavapaiensis), which exhibits an intermediate level of resistance to the pathogen. Some individuals demonstrate resistance while others of the same species die if infected with chytrid. The identification of genetic variations between the individuals holds the potential of being the answer between life and death. One of the new frontiers for genetic research is the examination of a frog species’ immune system genes.

“If we can identify the genes responsible for resistance, we can breed the animals in captivity to ‘spread’ this genetic resistance and give adaptation a headstart,” Savage said. “This area of research holds the potential for creating populations of self-sustaining frogs that confer resistance to the rest of the population through reproduction.”

Anna Savage with bullfrog

Savage's research could hold the key to putting a stop to a deadly pathogen killing frogs around the world.

In order to understand a frog’s response to chytrid, the focus must be broadened to understanding how immune system genes interact with one another and which ones are being expressed during resistance. Savage is using this approach to understand chytrid susceptibility in lowland leopard frogs that are being raised at the Smithsonian’s National Zoo. This approach could potentially help scientists identify genes responsible for chytrid resistance. While this type of research shows considerable potential, researchers are only just beginning to scratch the surface.

“Disease outcomes from chytridiomycosis can depend on several factors,” said Brian Gratwicke, SCBI wildlife biologist and Panama Amphibian Rescue and Conservation Project international coordinator.  “Some frogs appear to have innate resistance to the disease and produce antimicrobial peptides from glands in their skin. It is possible that some might acquire resistance through exposure, while other frogs have beneficial anti-fungal skin bacteria or a behavioral preference for temperatures that are bad for the fungus. As the fight against chytrid continues, we remain hopeful that the answers are out there and that Dr. Savage’s work will give us some insight into how this system really functions.”        

–Will Lazaro, Smithsonian’s National Zoo

(Frog photo by Jared Grummer; photo of Anna Savage by Dennis Caldwell)

I bet you can’t do this.

California slender salamander (Batrachoseps attenuatus)

California slender salamander (Batrachoseps attenuatus)

Cute Amphibian of the Week: November 19, 2012

The California slender salamander (Batrachoseps attenuatus), native to the United States, is known for its extremely long tail that allows it to wrap itself with its own tail giving it the appearance of a snake. Its bulgy eyes and bright coloration add to the charm of this small salamander. This species resides in grasslands with scattered trees, chaparral, woodlands and redwood forests. Perhaps one of its most fascinating features is the fact that it completely lacks lungs and breathes primarily through its skin.

Do not let this adorable salamander’s appearance fool you; this is one tough species that is able to tolerate considerable habitat alteration. When feeding, this species creates a pressure with its muscles, which allows it to dart its tongue and “shoot” its hyoid bone (neck bone) out of its mouth during this endeavor. Its most interesting features, however, are some of its defense mechanisms. It may drop its tail to avoid predation or even release an adhesive skin secretion, which can literally glue its predator’s mouth shut. At the current time the species is listed as least concern by the IUCN.

Photo by Brian Gratwicke, Smithsonian Conservation Biology Institute.

Every week the Panama Amphibian Rescue and Conservation Project posts a new photo of a cute frog from anywhere in the world with an interesting, fun and unique story to tell. Be sure to check back every Monday for the latest addition.

Send us your own cute frogs by uploading your photos here: http://www.flickr.com/groups/cutefrogoftheweek/

Things we are thankful for: Amphibian baby boom at EVACC and Summit Zoo

Reflecting on our achievements this last year, we would like to thank you, our generous supporters. You have provided moral support; social media likes and retweets generously; more than 40 of you have given us your time to help us save frogs; and even more have sacrificed your hard-earned money to help us achieve this important mission. Thank you! In particular I would like to recognize the extraordinary dedication and above-and-beyond service from our devoted conservation staff seen above proudly displaying the the captive-bred products of their hard work, including a second generation of captive-bred frogs at EVACC, and our first grown-up generation of captive-born frogs at the Summit Zoo. We salute you all.

Brian Gratwicke – International project coordinator for the Panama Amphibian Rescue and Conservation Project, Smithsonian Conservation Biology Institute

Rock star.

Chinese giant salamander (Andrias davidianus)

Chinese giant salamander (Andrias davidianus)

Cute Amphibian of the Week: November 19, 2012

The Chinese giant salamander (Andrias davidianus), native to China, is the largest living salamander growing to monstrous lengths of up to six feet. When camouflaged, this species resembles a large rock with its eyes barely perceptible amid its large body. It lives and breeds in large hill streams, usually in forested areas. Interestingly enough, this species has a range of vocalizations with one of them eerily sounding like a child crying, resulting in the nickname “the infant fish.”

These enormous salamanders can weigh as much as a whopping 58 pounds. Commercial overexploitation for human consumption is the main threat to this species, though habitat destruction and degradation also play a role. At the current time the species is listed as critically endangered by the IUCN.

Photo by Silvain de Munck.

Every week the Panama Amphibian Rescue and Conservation Project posts a new photo of a cute frog from anywhere in the world with an interesting, fun and unique story to tell. Be sure to check back every Monday for the latest addition.

Send us your own cute frogs by uploading your photos here: http://www.flickr.com/groups/cutefrogoftheweek/

Food for Frogs at EVACC: What it takes to raise the inverts served for dinner

Big frog, little frog, golden frog, marsupial frog, endangered frog, and common frog; what do all of those guys have in common? They all need to eat.  There is no call-up home delivery in Panama, so here in El Valle at EVACC, we have had to roll up our sleeves and become invertebrate breeders (adding to an eclectic list of “other skills” needed in this particular conservation project).

Lisandro Vasquez

Lisandro Vasquez, rolling up his sleeves in the cricket room at EVACC.

The thing that most people do not think about when thinking about an amphibian conservation project is food for the animals. It would be incredibly difficult to have a successful breeding/conservation project without being able to feed the subjects at hand. At EVACC we think about insects, and other invertebrates, on a very regular basis. And we think about what they eat, in a captive setting, just as much.

ingredients

Some of the ingredients that go into preparing insect diets.

What do our frogs eat?  We have quite a few different species we look after, so we have quite a few invertebrates to offer to them.  For the most part we delineate food items to specific species based on food size, and the mode in which the frog eats.  The smallest food we have to offer is springtails, from the insect order Collembola.  They go through simple metamorphosis, and the different size nymphs can be sifted and fed to different size amphibians.

Springtail colony

Springtail colony.

Working our way up through the sizes we have the two different kinds of fruit flies; Drosophila melanogaster and Drosophila hydei.  The two fruit flies at EVACC do not fly and the smaller one, D. melanogaster, does not have wings. They have both been genetically modified to possess these traits. Fruit flies, with vitamin powders, are fed alternately to our diurnal species, and to some of the nocturnal species at different stages in their life. These two species of Drosophilago go through complete metamorphosis.

Drosophila melanogaster in fly cup

Drosophila melanogaster in fly cup.

Drosophila hydei colony

Drosophila hydei colony.

Domestic crickets (Acheta domesticus) make up a large portion of the diet for many species at EVACC.  This captive food colony requires quite a bit of time and space, but well worth it.  This insect goes through incomplete or simple metamorphosis as well, making it a food item for the smallest of frogs to large ones, as well.

cricket box

Cricket box crawling with one-month-old nymphs.

Cricket breeding room

Cricket breeding room, boxes upon boxes of crickets stacked up at EVACC.

Woodlice, sow bugs, or roly-poly bugs are also on the menu at EVACC. These invertebrates are not insects, but a crustacean from the family Oniscidea.  Leaf litter frogs love these calcium-packed treats.

Woodlice

Woodlice at EVACC.

The super worm (Zophobas morio) is a larva of a species of darkling beetle. Only the larvae are fed out to amphibians, as the adult are not preferred foods for frogs. This insect goes through complete metamorphosis.

We also have a colony of earthworms. Our colonies are not thriving at the moment, so most of the time we harvest from our own backyard. The other food item that we are currently not breeding, but do feed out, is the Neoconocephalus saturatus, a type of cone-headed katydid. We rely on a local family to help us out by collecting these katydids for us.

Last, but certainly not least, is the newest food item on the menu at EVACC; Blaberus discoidalis, a very large cockroach.

Cockroach

Cockroach on the menu.

Larvae pupa and adult stages

Larvae, pupa, and adult stages of Zophobas morio

Heidi Ross, director of El Valle Amphibian Conservation Center

(All photos courtesy of EVACC)

MMMmmmmmmm…….chocolate.

W rain-peeper (Pristimantis w-nigrum)

W rain-peeper (Pristimantis w-nigrum)

Cute Frog of the Week: November 12, 2012

The W rain peeper (Pristimantis w-nigrum), native to Ecuador and Colombia, resides at vertigo-inducing heights of between 800 meters and 3,300 meters. As is the Latin American tradition, this species is a frog of many names and additionally referred to as the Zurucucho robber frog and the cualita. They can be found near streams or far from them, in cloud forest and sub-paramo habitats. It may not look it, but this is one hardy frog—it is able to tolerate substantial habitat disturbance. Major threats to this species include water pollution and potentially chytrid.

This species is called the W rain peeper because of its characteristic W-shaped mark on the scapular or shoulder region. The W rain peeper has a more neutral coloration and gruffer appearance, making it the tough guy among peepers. It possesses an inimitable marking around its mouth that makes it look like it just finished eating chocolate. Currently, this species is listed as least concern by the IUCN.

Photo by Alejandro Arteaga via Flickr.

Every week the Panama Amphibian Rescue and Conservation Project posts a new photo of a cute frog from anywhere in the world with an interesting, fun and unique story to tell. Be sure to check back every Monday for the latest addition.

Send us your own cute frogs by uploading your photos here: http://www.flickr.com/groups/cutefrogoftheweek/

Rescue project partner Houston Zoo wins grant to continue work on amphibian biodiversity in Borneo

Brown bullfrog (Kaloula baleata)

This brown bullfrog is one of a number of species that Houston Zoo and partners will be able to continue studying in Borneo thanks to this grant. (Photo courtesy of Houston Zoo)

The Houston Zoo and our partners at Hutan, Cardiff University and the Danau Girang Field Center (DGFC) were recently awarded a Conservation Endowment Fund (CEF) grant from the Association of Zoos and Aquariums (AZA).

The grant will allow the Zoo and our partners to build on the amazing work for the conservation of biodiversity that has been accomplished in Sabah in Borneo by Hutan and DGFC over the last few decades.

The primary threats in the area are the loss of primary and secondary forests to oil palm plantations. In 2008, Australian amphibian conservation biologist Dr. Graeme Gillespie began to work with Hutan and DGFC to include amphibians in their research and conservation programs.

Since 2008 they have intensively sampled the Lower Kinabatangan Wildlife Sanctuary and surrounding oil palm plantations to assess the amphibian fauna of the area. Results of the first phase were published in Biological Conservation earlier this year (Gillespie et al. 2012 152 (2012) 136–1440).

This grant will specifically address some of the questions relating to the value of the secondary forests for amphibian biodiversity by increasing the sampling done in primary areas. Once the dataset is assembled, we will be able to use this information to make additional recommendation for forest management.

Brian Hill, Houston Zoo

Now you see me…

Papillated rain-peeper (Pristimantis phoxocephalus)

Papillated rain-peeper (Pristimantis phoxocephalus)

Cute Frog of the Week: November 5, 2012

The papillated rain-peeper (Pristimantis phoxocephalus), native to Peru and Ecuador, is a small frog that resides at dizzying heights of between 1,800 and 3,100 meters. This species receives its namesake from the small papilla or protuberance on the tip of its nose. It has a characteristic banding around its eyes, which makes it seem like a mini bandit. The papillated rain peeper can be found in the upper humid montane forest at sub-paramo, but mostly on the edges as opposed to the interior. Both livestock and selective wood extraction threaten this adorable species by leading to destruction and loss of habitat.

This peeper, though common in Ecuador, is considered much rarer in Peru. Like most peepers, this species is known for its melodic vocalizations that can be heard throughout the forest edges. It has a unique pattern on its back of alternating brown and black dots, which make it stand out among the greenery, but allows it to disappear into the dead leaf litter. This makes it a veritable Houdini! Currently, this species is listed as least concern by the IUCN.

Photo by Alejandro Arteaga via Flickr.

Every week the Panama Amphibian Rescue and Conservation Project posts a new photo of a cute frog from anywhere in the world with an interesting, fun and unique story to tell. Be sure to check back every Monday for the latest addition.

Send us your own cute frogs by uploading your photos here: http://www.flickr.com/groups/cutefrogoftheweek/