Thursday, August 30, 2012

New Lady Molossus


Howdy Herpers,                                                   08/28/12

Two days ago, Gordo and I had just parked my battle-scarred truck in Suizo Wash. As we were egressing from the vehicle, we heard some hollering from above us on Iron Mine Hill. It was Marty Feldner, whom we had sent off to track a batch of animals that were not going to be on our list for the day.

"We've got a pairing up here. Marty the Prick has a girlfriend!" Marty shouted.

(Marty the Prick is our newest male black-tailed rattlesnake, CM14. He thus far has been wrongly accused, but we expect him to bomb all over the place any day now. Big male molossus have been know to go 1.5 miles in a day! We expect that from CM14--but thus far, he has been a good little prick in this regard. He has stayed close to Iron Mine Hill. The "Marty" in his inappropriate moniker appears because Marty was the person to find this snake. We fully expect to be cussing Marty the person when his namesake finally takes off. Which he WILL do, and soon, I'm sure.)

Since we had but one transmitter left for the year, and a female molossus was exactly what we wanted, I should have been ecstatic. Instead, the thought of dragging a female snake away from a male that had worked hard to find his girlfriend was bringing me down.

As Gordo will attest, there was a torrent of bitching emanating from my gullet all the way up the hill. Said bitching stopped for a few minutes when our path took us by a whopping male tortoise that was out basking in front his burrow. Two quick photos of that transpired, and we moved up to where Marty was staked out.

See image 1 below. The sight of the two snakes together in the same crevice was uplifting, but daunting as well. Getting the female (the snake on the left) out of that crevice was not going to be a picnic. It was quite possible we would spook it deeper if we bungled the attempt.

And so, off I went to try to bungle the attempt. Marty clamored to the boulder on top of the image to lend assistance if needed. Gordon took position behind me, and I sprawled into the prickly pear in front of the crevice. (This action is still causing some discomfort--but in six months, it will all go away).

The crevice was too narrow to get the tongs in, so I tried to get my snake hook in behind her. Instead of getting the hook behind her, I hit her smack in mid body. My heart sank, but this fumbling action caused her to do something that I've never seen before. She came right out of the crevice toward me! It's always better to be lucky than good!

So we snatched her effortlessly, and bagged her. There was still remorse in my heart for Marty the Prick, who could do nothing but stare at us from his crevice. Bummer for him--huh?

Once the tracking was behind us, we paused in our favorite "shady spot" to engage in the REAL reason for going out there. As this progressed, we removed our new female from the bag for some photos. See image 2.
A plan began to formulate. How can we get this girl back in the game asap? There was trio of consent.
Dale DeNardo can do it! He's our hero! We proceeded to call the hapless DVM, and he consented to perform the surgery the next day.

That night, I met Mr. Feldner with everything that was needed at a stop halfway between Phoenix and Tucson.

Last night, I met Mr. Feldner at the same spot. Everything was done and ready.

This morning, I worked my way back to the crevice. As soon as she was on the ground, she shot into the crevice. Half the job was done. I raised the antenna skyward with hope that Marty the Prick might be nearby.

Bingo--the signal was loud and clear. I found him 30 meters downslope of the crevice, moving away from it.

He was snagged, and carried back to his girlfriends lair. Like his lady love, he shot into the crevice as soon as he hit the ground.

See image 3.
I'm not sure if our meddling will result in successful reproduction with this pair. Time will tell, and we'll be watching.

One thing I do know for sure:
Both snakes will have a LOT to talk about...............

Best to all, roger


Thursday, August 23, 2012

USFW Proposes Four Texas Salamanders as Endangered

Eurycea tonkawae
The following has been adapted from an article by Mike Parker at the Cedar Park-Leander Statesman, published on August 21, 2012

The U.S. Fish and Wildlife Service proposed this morning (August 21, 2012) listing four Texas salamanders on the Endangered Species Act hours before the Williamson County Commissioners Court approved a resolution against the listings.

The Austin blind salamander (Eurycea waterlooensis), Jollyville Plateau salamnder (Eurycea tonkawae), Georgetown salamander (Eurycea naufragia), and Salado salamander (Eurycea chisholmensis) all live within Travis, Williamson and Bell counties, and the proposed listings would designate almost 6,000 acres as a critical habitat for the creatures.

The proposed listings stem from lawsuits filed by Save Our Springs Alliance and the Center for Biological Diversity, which call for the salamanders to be listed among 250 other species as endangered. Colette Adkins Giese, an attorney for the CBD, said the listings give the creatures a “fighting chance.”

“Giving them a critical habitat is a big help in giving them a path to recovery,” she said. “Those areas are essential for their habitat and will keep them from harm.”

Many local officials, county commissioners and federal officials have opposed the listing, saying it is unnecessary and detrimental to local development. In July, U.S. Rep. John Carter introduced the Salamander Community Conservation Act, HR 6219, which would block premature listing of the species as endangered without adequate scientific data to support such a decision, according to a press release.

Williamson County commissioners created the Williamson County Conservation Foundation, which is funding a five-year study on the salamanders. Commissioners have said there is not enough data on the four species to know if they are in need of protection. But Giese said the 346-page proposal from USFWS has ample evidence to support the listings.

“We feel the science behind it is taking the day instead of some of the political pressure heaped upon this,” she said.

Cedar Park Mayor Pro Tem Tony Dale has been a vocal opponent to the listings. In an editorial published by the Cedar Park-Leander Statesman, he wrote evidence collected by the WCCF study is showing expanding development is not harming the salamanders.

“Many of us involved in working on this issue have seen USFWS is using data that does not support its likely conclusion that the species is endangered,” he wrote.

USFWS is holding public hearings on the proposed listings. The first hearing is 5:30 p.m. Sept. 5 at the Wingate, 1209 N. IH-35 North in Round Rock, and the second hearing is 6:30 p.m. Sept. 6 at the Thompson Conference Center, 2405 Robert Dedman Dr., Room 2.102, in Austin.

Tuesday, August 14, 2012

More on Bullfrogs & BD

Photo by Lisa Schloegel. A bullfrog farm in Brazil. Bullfrogs are raised on farms in Taiwan, 
Brazil and Ecuador, then shipped live worldwide and sold as food for their legs.
ANN ARBOR, Mich. — The global trade in bullfrogs, which are farmed as a food source in South America and elsewhere, is spreading a deadly fungus that is contributing to the decline of amphibians worldwide, according to a University of Michigan biologist and his colleagues.

Amphibian populations are declining worldwide at an alarming rate, and the spread of the deadly chytrid fungus is believed to be a contributing factor. The fungus infects the skin of frogs, toads and salamanders.

In a study to be published in an upcoming edition of the journal Molecular Ecology, University of Michigan evolutionary biologist Timothy James and his colleagues examine the role of bullfrog farming in spreading the chytrid fungus between the forests and frog farms of Brazil and then to the United States and Japan.

The researchers collected and analyzed bullfrogs sold at Asian food shops in seven U.S. cities and found that 41 percent of the frogs were infected with chytrid fungus, which is harmless to humans. Frogs in these shops are imported live primarily from farms in Taiwan, Brazil and Ecuador and sold as food for their legs.

James and his colleagues also analyzed bullfrogs from frog farms in Brazil and several native frog species from Brazil’s Atlantic Forest, one of the most amphibian-rich regions in the world. Their DNA sequencing studies identified the various strains of the chytrid fungus, Batrachochytrium dendrobatidis or Bd for short, present in the frogs.

The studies revealed four previously unknown strains of chytrid, including one that was present on a live bullfrog sold for frog legs in an Asian market in southeastern Michigan. The team determined that the Michigan bullfrog probably came from a frog farm in Brazil’s Atlantic Forest. Sampling of native frogs in that region revealed that the four closely related strains, known collectively by the researchers as the Brazilian strain or Bd-Brazil, are common in Brazil. By comparing their results to data in a previously published study, the researchers showed that the Brazilian strain is also present in bullfrogs in Japan.

The data suggest that the Bd-Brazil chytrid strain probably originated in Brazil among native frogs, rather than being introduced to the country by imported bullfrogs. The Bd-Brazil strain likely spread from infected native frogs to a Brazilian bullfrog farm and from there to other locations in bullfrogs shipped globally.

The North American bullfrog, an aggressive, carnivorous species originally native to eastern North America, is resistant to the chytrid fungus and therefore makes an excellent carrier, or vector, of the disease.

“Our data suggest that chytrid strains have been vectored across the globe by bullfrogs, which may have ultimately led to the disease being so widespread,” said James, an assistant professor in the Department of Ecology and Evolutionary Biology.

“A lot of the movement of this fungus is related to the live food trade, which is something we should probably stop doing,” James said. “We don’t need to have millions of live frogs being shipped from foreign countries into the United States.”

Nearly 5 million live frogs – more than half of them bullfrogs sold for food – are shipped to the United States each year. A previous study by the lead author of the Molecular Ecology paper, Lisa Schloegel, estimated that about half of those frogs are infected with chytrid fungus.

The Brazilian strain of chytrid fungus uncovered by James and his colleagues is genetically very different from the hyper-virulent global strain blamed for amphibian losses. But one of the team’s key findings provides “compelling evidence for the hypothesis that the global trade of amphibians may have significantly contributed to the emergence of hyper-virulent strains of Bd,” according to biologists Valerie McKenzie and Anna Peterson of the University of Colorado, who co-authored a News & Views Perspective article for Molecular Ecology about the James team’s findings.

Among the strains isolated from native frogs in the Atlantic Forest was one that was the product of sexual reproduction between two genetically distinct chytrid strains. Most fungi are able to produce both sexually and asexually, but sexual reproduction had not previously been observed in the chytrid fungus, James said.

The observation of sexual reproduction in the chytrid fungus opens the door to the possibility that two genetically dissimilar strains of chytrid could breed to create a hybrid strain with increased virulence.

McKenzie and Peterson note that there is a healthy debate among chytrid researchers about whether the deadly fungus is a globally endemic organism that only recently started causing high mortality or the result of a virulent strain created from the hybridization of different chytrid strains that came into contact in recent decades, then rapidly spread around the world.

The new findings from James and his colleagues “provide credence to the hybridization hypothesis for the origin of the pandemic by demonstrating sex in chytrid for the first time,” James said. “We now know that hybridization is possible, and we know that there’s strain mixing going on through animal introductions. You put those findings together and it predicts that future epidemics could also occur through more strain mixing.”

The genetic hybrid discovered by the researchers is likely the result of sexual reproduction between the Bd-Brazil strain and one of the highly virulent strains blamed for amphibian die-offs. Those highly virulent strains of Bd are known as the global panzootic lineage, or Bd-GPL.

Citation
SCHLOEGEL, L. M., TOLEDO, L. F., LONGCORE, J. E., GREENSPAN, S. E., VIEIRA, C. A., LEE, M., ZHAO, S., WANGEN, C., FERREIRA, C. M., HIPOLITO, M., DAVIES, A. J., CUOMO, C. A., DASZAK, P. and JAMES, T. Y. (2012), Novel, panzootic and hybrid genotypes of amphibian chytridiomycosis associated with the bullfrog trade. Molecular Ecology. doi: 10.1111/j.1365-294X.2012.05710.x

Snake & Viruses



A novel virus has been identified as the possible cause of a common but mysterious disease that kills a significant number of pet snakes all over the world, thanks to research led by scientists at the University of California, San Francisco (UCSF)—and three snakes named Juliet, Balthazar and Larry.

The virus, previously not thought to infect snakes at all, appears to cause "inclusion body disease." Long the bane of zoo officials and exotic pet owners, the deadly illness spreads among boas and pythons in captivity, causing micro clumps of clustered proteins to form inside the snake, leading to bacterial infections, neurological problems, anorexia and withering, leading to death.

The new work, described this week in the American Society for Microbiology's new open-access journal mBio, paves the way toward developing diagnostics and treatments, which may make it possible to eradicate the disease from snake collections worldwide.

"It's a devastating disease when it gets into a collection, zoo or aquarium because it's essentially fatal every time," said Joe DeRisi, PhD, the senior author of the study, a Howard Hughes Medical Institute investigator (HHMI) and vice chair of the Department of Biochemistry and Biophysics at UCSF.

Surprisingly, he said, the cause of the illness appears to be a completely new set of viruses of a type known as an arenavirus. The discovery came as a complete a shock to the team of scientists because, while arenaviruses are common in rodents and cause extremely nasty infections in other mammals, nobody knew they could infect reptiles.

"Now we have found that they infect snakes, as well," said Mark Stenglein, PhD, a postdoctoral fellow at UCSF who is the first author on the paper.

Stenglein, DeRisi and their colleagues isolated at least two strains of the arenaviruses from half a dozen snakes afflicted with inclusion body disease. They could find no traces of the same viruses in snakes that were free from disease.

Arenaviruses infect mostly rodents but occasionally people, and can cause fatal hemorrhagic diseases like Lassa fever, which kills thousands of people every year in Africa. There is no evidence, however, that a snake has ever transmitted an arenavirus infection to a person despite the fact that snake owners and veterinarians handle infected snakes all the time, said DeRisi.

For years, many experts have hypothesized that a virus or some other infectious pathogen might cause inclusion body disease because of evidence that it spreads easily from snake to snake. No definitive cause has been identified until now, and the discovery may never have occurred if not for a random sequence of events, including cases of inclusion body disease in an aquarium collection, a friendly DNA sequencing competition among scientists, a postdoctoral researcher who was looking for a project, and a snake owner worried about her favorite pet.

The story began with a snake named Larry, and his owner, Taryn Hook of San Jose, California. Before Larry, Hook had lost two snakes to inclusion body disease, and, in early 2009, she became convinced Larry had it as well. He was developing bacterial infections similar to what Hook had seen with her two other snakes. Knowing there was no treatment or cure, she was desperate to find anyone who might save her snake.

Hook took Larry to see the exotic pet veterinarian Chris Sanders, DVM, owner of the nearby Wildwood Veterinary Hospital. Sanders had just attended a conference at which he had heard DeRisi talking about his Virochip DNA microarray technology and its ability to identify viruses, fungi and other pathogens—including at least one exotic pet disease, a mysterious parrot virus—when no other gene probing technology could. The parrot virus was discovered by DeRisi and Don Ganem, MD, at the time an HHMI investigator and professor of microbiology and medicine at UCSF, in 2008.

Could DeRisi help save Larry the snake as well? Sanders suggested to Hook she had nothing to lose by asking.

DeRisi was in his office one morning in early 2009 when he spied a hand-written letter in his stack of daily mail. Inside was a plea from Hook describing Larry's illness. She had heard he had found the cause of a mysterious parrot disease. Would he do for snakes what he did for parrots? She enclosed a picture of herself with Larry.

Having never heard of the disease, DeRisi set the letter aside and it was lost under a pile of paper. Only months later, while cleaning his office, did he stumbled across it again. He was about to toss it away, but in scanning the letter again he noticed Hook mentioned the local exotic pet veterinarian Sanders. So he called, they spoke, and DeRisi decided to take on the project.

"It satisfied all the criteria as an interesting disease," DeRisi said. But first he had to find samples to test from infected snakes.

Around the same time, inclusion body disease was diagnosed in a snake at the Steinhart Aquarium in the California Academy of Sciences in San Francisco. Also discovered were snake mites, which are believed to be a possible vector for passing the disease from snake to snake.

Academy veterinarian Freeland Dunker decided to test all of the boas exposed to the infected snake for the disease—a complicated procedure requiring a surgical biopsy of the liver. He discovered a few more were infected, and all of them had to be euthanized to prevent any spread of the disease. Dunker asked his pathologist, Drury Reavill DVM if she knew of any current research being done on inclusion body disease for which tissues from the euthanized snakes could be used. As it turned out, Reavill had already been in touch with DeRisi's group and knew they were looking for samples.

The effort to find the virus went into overdrive after Stenglein joined the DeRisi laboratory as a postdoctoral fellow and took on the project. But before he and DeRisi could find traces of the virus they needed to know the sequence of the boa constrictor genome so they could distinguish snake DNA sequences from viral sequences in the diseased animals. The problem was that there were no snake genomes available.

Thus, their first step was to sequence the entire boa constrictor genome, and they had to start with a snake that they were sure was free of inclusion body disease. At the Academy, Dunker helped in this effort by collecting blood from a boa constrictor named Balthazar, an education animal which was housed separately, had no contact with the rest of the boa snake collection and tested negative for the inclusion body disease.

Substantial help in the sequencing effort came from scientists participating in a friendly competition called the Assemblathon 2, which was sponsored by UC Santa Cruz and UC Davis. Balthazar's DNA was sequenced and a number of groups around the country competed to build (assemble) the most complete genome sequence possible using the raw data.

Characterizing Balthazar's genome paved the way for finding the arenavirus in the midst of millions of other sequences of the snakes' DNA. This "needle in the haystack" problem was solved using custom software written in the DeRisi lab, and made available for free on his website.

The team found two arenavirus strains in the snakes—a surprise in itself; but in addition, they observed that theviruses did not look like your ordinary arenaviruses. They looked like distant relatives of other arenaviruses but had protein coats that were more similar to those of Ebola viruses. Like arenaviruses, Ebola virus can cause fatal hemorrhagic fever when transmitted to humans. Neither of those viruses has ever been known to infect reptiles, and although it had been postulated that they share a common ancestor, no such virus linking them had ever been discovered.

Once the virus was computationally identified, the team had to find a way to grow the virus so that it could be studied further. Because the virus infects boa constrictors, the ideal way to grow it, the team reasoned, would be to infect boa constrictor cells, but no such cell line existed. So DeRisi and Stenglein turned to a third snake, named Juliet.

Juliet was a red tailed boa owned by Chris Sanders, who'd had her since his days as a young veterinary student. She was about 20 years old when Balthazar's genome was being assembled and was dying of lymphoma. When she ultimately succumbed to the cancer, Sanders harvested her kidneys and the DeRisi laboratory was able to use them to make a boa constrictor cell line.

The scientists took virus from diseased snakes, added it to Juliet's kidney cells growing in petri dishes and showed that the snakes accumulated exactly the same "clumps" of proteins as had been observed in the sick snakes from the Academy. Antibodies raised against the virus showed that these clumps were formed from arenavirus protein, further strengthening the association of this new virus and the deadly disease.

In solving this longstanding veterinary mystery and setting the stage for treatments, vaccines, and perhaps even eradication of this disease, the scientists also discovered an unexpected new branch of virus biology: The viruses they found appear to be a combination of arenaviruses and filoviruses, neither of which has been known to infect reptiles.




Citation

Mark D. Stenglein, Chris Sanders, Amy L. Kistler, J. Graham Ruby, Jessica Y. Franco, Drury R. Reavill, Freeland Dunker, and Joseph L. DeRisi. 2012. Identification, characterization, and in vitro culture of highly divergent arenaviruses from boa constrictors and annulated tree boas: a candidate etiological agent for snake inclusion body disease (IBD). mBio: http://dx.doi.org/10.1128/mBio.00180-12

Largest Everglades Python Found to Date

GAINESVILLE, Fla. — On Aug. 10, 2012, researchers at the Florida Museum of Natural History on the University of Florida campus examine the internal anatomy of the largest Burmese python found in Florida to date. The 17-foot-7-inch snake weighed 164 pounds and carried 87 eggs in its oviducts, a state record. Following scientific investigation, the snake will be mounted for exhibition at the museum for about five years, and then returned for exhibition at Everglades National Park. Pictured are Rebecca Reichart (from left), Leroy Nunez, Nicholas Coutu, Claudia Grant and Kenneth Krysko. University of Florida Photo by Kristen Grace.

GAINESVILLE, Fla. — University of Florida researchers curating a 17-foot-7-inch Burmese python, the largest found in Florida, discovered 87 eggs in the snake, also a state record.

Scientists at the Florida Museum of Natural History on the UF campus examined the internal anatomy of the 164.5-pound snake Friday. The animal was brought to the Florida Museum from Everglades National Park as part of a long-term project with the U.S. Department of the Interior to research methods for managing the state’s invasive Burmese python problem. Following scientific investigation, the snake will be mounted for exhibition at the museum for about five years, and then returned for exhibition at Everglades National Park.

“This thing is monstrous, it’s about a foot wide,” said Florida Museum herpetology collection manager Kenneth Krysko. “It means these snakes are surviving a long time in the wild, there’s nothing stopping them and the native wildlife are in trouble.”

Krysko said the snake was in excellent health and its stomach contained feathers that will be identified by museum ornithologists. Burmese pythons are known to prey on native birds, deer, bobcats, alligators and other large animals.

“A 17.5-foot snake could eat anything it wants,” Krysko said. “By learning what this animal has been eating and its reproductive status, it will hopefully give us insight into how to potentially manage other wild Burmese pythons in the future. It also highlights the actual problem, which is invasive species.”

Native to Southeast Asia and first found in the Everglades in 1979, the Burmese python is one of the deadliest and most competitive predators in South Florida. With no known natural predator, population estimates for the python range from the thousands to hundreds of thousands. They were determined to be an established species in 2000 and are a significant concern, Krysko said.

“They were here 25 years ago, but in very low numbers and it was difficult to find one because of their cryptic behavior,” Krysko said. “Now, you can go out to the Everglades nearly any day of the week and find a Burmese python. We’ve found 14 in a single day.”

The rapid population growth led to recent state laws prohibiting people from owning Burmese pythons as pets or transporting the snakes across state lines without a federal permit. Florida residents also may hunt pythons in certain wildlife management areas during established seasons with a hunting license and required permits.

Everglades National Park and the Florida Fish and Wildlife Conservation Commission are partnering with other agencies to address the increasing populations.

Skip Snow, a park wildlife biologist, said research of the snake’s biology is important for understanding how to curtail the future spread of invasive species.

“I think one of the important facts about this animal is its reproductive capability,” Snow said. “There are not many records of how many eggs a large female snake carries in the wild. This shows they’re a really reproductive animal, which aids in their invasiveness.”

Non-native species are considered invasive if they have a negative impact on native species or habitat, cause economic damage or pose a threat to human health and safety. Exotic snakes found in Florida are often the result of pet owners accidentally or intentionally releasing the animals. Citizens may dial 1-800-IVE-GOT1 to receive removal assistance by trained handlers.

Previous records for Burmese pythons captured in the wild were 16.8 feet long and 85 eggs.

“I’m really happy to be part of this team of researchers working on the Burmese python problem in Florida, and have been for a number of years,” Krysko said. “But when I’m able to conduct this type of research here at the university, I’m able to teach new students and new researchers about python anatomy and discuss the problem with invasive species. We need all the help we can get, we really do.”

Florida has the world’s worst invasive reptile and amphibian problem. Krysko led a 20-year study published in September 2011 in Zootaxa showing 137 non-native species were introduced to Florida between 1863 and 2010. The study verified the pet trade as the No. 1 cause of the species’ introductions and the Burmese python was one of 56 non-native species determined to be reproducing and established in the state.

Monday, August 13, 2012

Survivorship in Hatchlings of Two Species of Emydid Turtles.

A hatchling Blanding's Turtle, Emydoidae blandingii

Turtles are one of the most endangered reptile clades worldwide and information about their population ecology is essential for species recovery. Although adult spatial ecology and demography of several turtle species is well studied, little is known about early life stages. The small size, soft shell, and limited mobility of hatchling turtles may result in differences in survivorship and habitat selection when compared to compared adults.

Paterson et al. (2012)  tested the hypothesis that hatchling turtles select habitat as they move away from nests to reduce the risk of predation and desiccation. They  examined survivorship, behaviour and habitat selection in hatchling Blanding’s turtles (Emydoidea blandingii) and wood turtles (Glyptemys insculpta) in 2009 and 2010, using radio-telemetry. In addition, temperatures of sites used by hatchlings during winter were compared with those at haphazard stations in various habitats.The study was done in Algonquin Provincial Park, Ontario, Canada.

 They found the hatchling mortality rate was high, with only  42% of Blanding's Turtles and 11% of of wood turtle hatchlings surviving to winter; most mortality was caused by predation. Behavioural observations for both species were mostly  of individuals hiding under cover. Both species showed evidence of macrohabitat and microhabitat selection as they dispersed from nests towards overwintering sites, and important variables in the models differed between species. Likewise, the adult stages of these two species differ in their macrohabitat specialisation. There was also evidence that hatchlings chose overwintering sites on the basis of temperature. Despite significant differences in survivorship between hatchlings and adults, resource selection was similar between these two demographic stages, and conservation plans based on adult habitat use should simultaneously protect hatchlings. Understanding habitat selection by juveniles is important for testing hypotheses about ontogenetic shifts in resource selection and for protecting habitat for species at risk.

Citation:
Paterson, J. E., Steinberg, B. D., and Litzgus, J. D. (2012) Revealing a cryptic life-history stage: differences in habitat selection and survivorship between hatchlings of two turtle species at risk (Glyptemys insculpta and Emydoidea blandingii). Wildlife Research 39, 408–418.

Saturday, August 11, 2012

New Light on Rattlesnake Foraging Behavior

Crotalus ruber

Rattlesnakes rely on multiple sensory systems during foraging and like all pit vipers, rattlesnakes have a pair of heat sensitive, image-forming pits located on the front of their face. Thermal cues from these pits are integrated with visual cues in the central nervous system to produce a single image of the environment . The pits are particularly good at detecting warm images against cool backgrounds and therefore compensate for the reduced levels of ambient light at night. Aditionally, snakes rely on a chemosensory system that is not limited by the amount of light and they can obtain chemical cues in two ways: a nasal olfactory system that detects volatile chemicals; and a vomeronasal system which may obtain volatile and non-volatile chemical cues through tongue-flicking . The degree to which rattlesnakes rely on chemical and thermo-visual cues varies during the foraging process. Matt Barbour and Rulon Clark used radio telemetry and video surveillance cameras to quantify the sit-and-wait chemosensory foraging behavior of free-ranging red diamond (Crotalus ruber) and northern Pacific (Crotalus oreganus oreganus) rattlesnakes during day and night periods. The two most common behaviors they observed were chemosensory probes, a behavior they describe for the first time, and mouth gapes. During a chemosensory probe, the rattlesnake extends their head beyond their coil, explores the surrounding area while tongue-flicking, and subsequently return to a stationary position inside their coil. Foraging rattlesnakes probed at significantly higher rates at night than during the day. The snakes also mouth gaped at a higher percentage of nocturnal vs. diurnal hours for foraging snakes. Almost half of all mouth gapes were followed immediately with a chemosensory probe, suggesting that mouth gaping also serves a chemosensory function. Their results suggest that chemical cues play an increasingly important role in mediating rattlesnake foraging behavior at night. Examining how abiotic factors, such as light availability, influence the sensory ecology of free-ranging predators is essential for accurately characterizing their interactions with prey.
Citation
Barbour, M. A. and Clark, R. W. (2012), Diel Cycles in Chemosensory Behaviors of Free-Ranging Rattlesnakes Lying in Wait for Prey. Ethology, 118: 480–488.

Thursday, August 9, 2012

Amphibian Milestone - 7000 Species

This new species of high-altitude glass frog, 
Centrolene sabini, in the amphibian family of
 Centrolenidae, was discovered by Allessandro 
Catenazzi in the cloud forest of Peru's Manu 
National Park at an elevation of nearly 
10,000 feet. This Peruvian glass frog tadpole, 
Centrolene sabini, was hatched from eggs
laid on the surface of a leafin Peru's Manu 
National Park.. Photo: Alessandro Catenazzi / SF

The total number of amphibian species reached 7,000  on Monday, July 31 2012. The 7000th known amphibian is a new glassfrog from Peru, Centrolene sabini (Catenazzi et al 2012), which was discovered at high elevations in Manu National Park, Peru. Glassfrogs have increased from 65 in 1985 to 152 known today, illustrating the paradoxical phenomenon of amphibian discovery during a time of great concern for amphibians. In June 2012, IUCN reported 41% of amphibian species at risk of extinction. Yet, the number of known amphibian species has increased dramatically, from 4,013 in 1985 to 7,000.

Citation
ALESSANDRO CATENAZZI, RUDOLF VON MAY, EDGAR LEHR, GIUSSEPE GAGLIARDI-URRUTIA  & JUAN M. GUAYASAMIN. 2012. A new, high-elevation glassfrog (Anura: Centrolenidae) from Manu National Park, southern Peru. Zootaxa  3388: 56–68

When Geckos Get Their Feet Wet

University of Akron Photo.
Scientists already know that the tiny hairs on geckos’ toe pads enable them to cling, like Velcro, to vertical surfaces. Now, University of Akron researchers are unfolding clues to the reptiles’ gripping power in wet conditions in order to create a synthetic adhesive that sticks when moist or on wet surfaces.

Place a single water droplet on the sole of a gecko toe, and the pad repels the water. The anti-wetting property helps explain how geckos maneuver in rainy tropical conditions. However, saturate that same toe pad in water or drench the surface on which it climbs, and adhesion slips away, the researchers say

As researcher Alyssa Stark, a doctoral candidate in UA’s Integrated Bioscience Program and research team leader explains, geckos don’t fall from trees during downpours in the tropics. What, then, makes them stick? The team hopes to make that discovery in order to create synthetic materials that hold their grip in wet environments, such as inside the body, for surgical procedures.

Findings by Stark, Timothy Sullivan, who received his bachelor’s degree in biology in May, and Peter Niewiarowski, UA professor of biology and integrated bioscience, are published in the August 9, 2012 issue of The Journal of Experimental Biology.

“We’re gathering many clues about how geckos interact with wet surfaces and this gives us ideas of how to design adhesives that work under water,” says Ali Dhinojwala, UA department of polymer science chair and Morton professor of polymer science. “Nature gives us a certain set of rules that point us in the right direction. They help us understand limitations and how to manipulate materials.”

Stark and her research team members tested gecko toe hair adhesion in a series of scenarios: dry toe pads on dry, misted and wet surfaces and soaked toe pads on dry, misted and wet glass. The soaked toe pads demonstrated low to no adhesion proportionately with the wetness of the surface on which they were applied and pulled. Likewise, dry toe pads lost their adhesive grip increasingly with the amount of water applied to the surface upon which they were pulled. For the experiments, geckos were pulled on a glass surface by way of a small, gentle harness placed around their midsections.

“There were anecdotes before the study that geckos can’t stick to wet glass. We now know it is a bit more complicated than that. What we expect to learn is going to be relevant to synthetics and ther capabilities to work not only on dry surfaces, but also wet and maybe, submerged ones,” Niewiarowski says. “This implies a more versatile adhesive capability.”

After close study of the tiny hairs at the bottom of gecko feet that enable them to cling to surfaces, Dhinojwala and his colleagues have already developed a dry synthetic adhesive, comprised of carbon nanotubes, that outperforms nature’s variety. Now, with these new findings, Dhinojwala and his colleagues are one step closer to unfolding the secrets behind gecko toe adhesion in wetness.

The researchers plan to further study the lizards in their natural habitats and in laboratory conditions that simulate them. They’ll investigate grasping and release mechanisms, habits of the geckos in wet environments and other factors that enable the lizards to adhere to surfaces in wetness, such as to trees during rainfalls.

“Our goal is to go back and look at what they’re doing in nature and at what kind of surfaces they are walking or running on,” says Stark, noting that UA researchers have already studied such behavior of geckos in Tahiti

Citation
A. Y. Stark, T. W. Sullivan, P. H. Niewiarowski. The effect of surface water and wetting on gecko adhesion. Journal of Experimental Biology, 2012; 215 (17): 3080 DOI: 10.1242/jeb.070912

Monday, August 6, 2012

Snake bite victims given wrong treatment

The tiger snake, Notechis scutatus.

The following story is from the Australia media outlet 9News, but the original article it is based upon is cited at the bottom of the post with a link.

Many snake-bite victims have been given the wrong antivenom because of flaws in a common test for tiger snake venom, a study shows.

An analysis of tiger snake bite cases between 2004 and 2011 has found the sVDK test used to detect the venom is unreliable.

A quarter of the cases tested negative for tiger snake venom, and in four cases patients were given anti-venom for brown snake bites instead.

Fortunately there were no adverse effects because brown snake antivenom can provide protection against poison from several snake species.

The study, led by toxicologist Associate Professor Geoffrey Isbister of the University of Newcastle, also found some bite victims had been given four or more vials of tiger snake antivenom, when one vial - as initially recommended by manufacturer CSL - was sufficient.

A total of 56 tiger snake bites were identified over the seven-year period from a database drawn from more than 100 Australian hospitals.

Nine of the bites were inflicted by snakes in captivity.

Nearly all victims suffered blood-clotting abnormalities, a third suffered neurotoxicity which affected nerves, while nausea, vomiting and headache were common symptoms.

No deaths were reported.

"Our study brings into question the reliance on the sVDK test for determining appropriate antivenom treatment," the report on the study, published in the Medical Journal of Australia, says

"The sVDK result was incorrect in five out of 44 cases, giving a positive result for brown snake venom, which led to the incorrect use of antivenom in four of the five cases.

"The use of sVDK is thus problematic and may confuse clinical assessment," the authors say.

The data shows one vial of antivenom to treat tiger snake bites is an adequate dose, they say.

Citation
Geoffrey K Isbister, Margaret A O’Leary, Matthew Elliott and Simon G A Brown. 2012. Tiger snake (Notechis spp) envenoming: Australian Snakebite Project (ASP-13). Med J Aust 2012; 197 (3): 173-177

Sunday, August 5, 2012

Do Snakes Have Necks?



Erpeton tentaculus. Is this animals mostly an elongated neck?
Garth Underwood, has been reported to have said that "....snakes are not necks..." in response to research that suggested that snakes evolved from lizards by  elongating  their cervical regions at the expense of their bodies.

The absence of a pectoral girdle in snakes makes it difficult to determine whether or not snakes have a distinct neck, and it clouds an understanding how the neck and trunk of snakes evolved  from their limbed lizard ancestor.  Tsuihiji and colleagues (2012) found three alternative hypotheses that had been proposed over the years about snake necks: (1) The neck in snakes is extremely elongated. (2) The cervical region is completely lacking in snakes. (3) The various anatomical structures usually associated with the neck–trunk boundary in squamates with limbs are displaced relative to one another in snakes.

Hypothesis 1 was based on the fact that snakes have numerous precloacal vertebrae bearing hypapophyses as well as have the heart and lung positioned rather posteriorly. Similarly, some authors regarded snakes as having a very long neck based on the posterior extent of hypapophysis-bearing vertebrae and then proposed the presence of such  a long neck as a potential synapomorphy that unites snakes and the Cretaceous dolichosaurids as sister clades, an idea first proposed by Nopcsa  in  1908. The possible presence of a long neck in ancestral snakes has led to the hypothesis that the ancestral snake lived in an aquatic environment.

Hypothesis 2 was proposed by Cohn and Tickle (1999), who observed that the anterior expression boundaries of two HOX proteins (HOXC8 and C6) that are located in the trunk region or close to the neck–trunk boundary in other tetrapods extend up to the craniovertebral boundary in the somites and lateral plate mesoderm in Python sp. These expression patterns were interpreted as indicating that the entire precloacal vertebral column has a ‘‘dorsal’’ or trunk identity with no actual cervical region present in this species. Cundall and Greene (2000) also suggested that the cervical and anterior trunk regions are absent in snakes based on observations that ribs, hypaxial muscles, and the pleuroperitoneal cavity all extend to the craniovertebral boundary in snakes.

 Hypothesis 3 was proposed by Hoffstetter and Gasc (1969), who observed that the anatomical structures usually associated with the neck–trunk boundary in limbed  lizards such as  the anterior end of the body wall musculature, posterior extents of the hypapophyses and subvertebral musculature, and position of the heart, tend to be displaced relative to one another in snakes. Hoffstetter and Gasc proposed that elongation of the precloacal region in snakes cannot be attributed solely to elongation of the cervical region.

Thus, various anatomical structures have been proposed as landmarks delimiting the neck–trunk boundary in snakes in the past. However, the axial myology has not been extensively examined for  defining the neck–trunk boundary of snakes despite the fact that the morphology of the axial muscles itself has been studied rather intensively in snakes.

But, Pregill (1977) examined changes in the axial myology in the anterior precloacal region toward the head in several colubrid snakes and demonstrated differentiation and emergence of craniovertebral muscles inserting on the skull as seen in the cervical as well as the anterior trunk regions of lizards with limbs. He concluded snakes have a distinct neck based upon the musculature. Similarly, Al Hassawi (2007) showed the presence of craniovertebral muscles in the viperid Trimeresurus (=Tropidolaemus) wagleri. These results agree with previous observations by Nishi (1916) that Python molurus has modifications of the axial musculature producing craniovertebral muscles homologous with those in four-legged lizards, but he did not specifically address the issue of the snake neck.

Tsuihiji and colleagues (2012) examined the cervical and trunk regionalization of the precloacal musculoskeletal system in snakes based on observations of the axial myology, using an approach similar to the one used by Pregill (1977). In particular, they  focused on the positions where craniovertebral muscles arise in various noncolubroid snakes to shed light on the plesiomorphic location of the neck–trunk boundary in snakes. In addition, several other limb-reduced squamates such as amphisbaenians that still retain vestigial pectoral girdle elements were compared to snakes. Based these observations, they attempted to test the three hypotheses concerning the neck–trunk boundary of snakes outlined above.

They found that the four craniovertebral muscles in lizards and reduced-limb squamates are also present in all  of the snakes they examined, confirming observations by Nishi (1916), Pregill (1977), and Al Hassawi (2007) that the anterior-most  region in snakes shows the same modification of vertebral muscles as observed in the cervical region of limbed lizards and has musculature  distinct from the more posterior region.

Tsuihiji and colleagues (2012)  confirmed the musculature features characterizing the neck in  squamates with well-developed limbs are retained in all examined snakes, contradicting the idea that snakes completely lack a neck  However, the posterior-most origins of the craniovertebral muscles and the anterior-most bony attachments of the body wall muscles that are located at  the neck–trunk boundary in limbed lizards are dissociated anteroposteriorly in snakes. This combined with results of a recent study that shows the anterior expression boundaries of Hox genes coinciding with the neck–trunk boundary in amniotic tetrapods  were dissociated anteroposteriorly in a colubrid snake, support the hypothesis that structures usually associated with the neck–trunk boundary in limbed lizards are displaced relative to one another in snakes.  Therefore suggesting that the trunk of the body, not the neck contributed most to the elongation of the snake.

Citation
Tsuihiji, T., Kearney, M. and Rieppel, O. (2012) Finding the neck–trunk boundary in snakes: Anteroposterior dissociation of myological characteristics in snakes and its implications for their neck and trunk body regionalization. Journal of  Morphology. doi: 10.1002/jmor.20037

Natracine Snakes Came Out of Asia to Colonize Africa and the Western Hemisphere

Natracines, often called water snakes, have a Holarctic distribution with about 29 genera and 210 species found across Asia, Europe, North Africa, sub-Saharan West Africa, as well as North and Central America. Many of these snakes are associated with aquatic habitats and feed on fish and frogs, some have adapted to xeric conditions and may feed on invertebrates or mammals. Molecular studies suggest the natricines evolved from a colubroid ancestor in the Eocene/Oligocene, suggesting they most likely encountered the same environmental conditions as the ratsnakes, skinks and crotalinae snakes as they dispersed across the globe. Molecular studies suggest the New World natricines form a monophyletic group (the Thamnophiini) implying they originated from a single dispersal event from an Old World ancestor. Edmund Malnate (1960) had previously hypothesized natricines originated in Asia and dispersed from there to Europe, Africa, Australia and North America, and that Natrix (sensu lato) dispersed to North America over the Bering Strait. Given the timing of origin of the global natricines in Eocene, it is also possible that they could have colonized the New World via the Atlantic through the Thulean Land Bridge or though the Pacific via Beringia. However, dispersals after the first half of the Cenozoic are unlikely to have occurred via the Thulean Land Bridge, due to declining environmental conditions suitable for ectotherms. Crucially, relationships among Old World genera and Thamnophiini are unclear, and divergence dating and ancestral area reconstructions are needed to understand basic biogeographic patterns relating to areas of origin, dispersal, and the rise of the several regional assemblages. 
Pen Guo of the College of Life Science at Yibin University in China and a researh team of other Chinese workers, as well as two Americans (R. Alexaner Pyron and Frank Burbrink) examine the temporal and geographic origins of natricine snakes in order to provide a comparison to the patterns and timing of origin of the ratsnakes, skinks, and crotalines, which all demonstrate similar timing and routes of dispersal through Beringia to the New World. In addition to sequencing several new species, they test hypotheses about the timing and area of origin of natricines in the Old W.orld . They also attempt to understand the causes of the Holartic distribution, which for the other groups of squamates have suggested a single unidirectional dispersal from Asia through Beringia to the New World during the Oligocene and Miocene (the Cenozoic Beringial Dispersal Hypothesis).

Using a combination of six mitochondrial gene fragments (12S RNA, cyt b, ND1, ND2, ND4 and CO1) and one nuclear gene (c-mos) from 22 genera the authors infered phylogenetic relationships among natricine snakes and examine the date and area of origin of these snakes. The phylogenetic results indicate the subfamily Natricinae is strongly supported as monophyletic including a majority of extant genera, and a poorly known and previously unassigned species Trachischium monticola; two main clades are inferred within Natricinae, one containing solely taxa from the Old World and the other comprising taxa from a monophyletic New World group with a small number of Old World relatives. They found that within the Old World clade, the genera Xenochrophis and Amphiesma are apparently not monophyletic. Divergence dating and ancestral area estimation indicate that the Old World natricines originated in tropical Asia during the later Eocene or the Oligocene. Additionally they recover two major dispersals events out of Asia, the first to Africa in the Oligocene, 28 million years ago and the second to the Western Palearctic and the New World at 27 million years ago. This date is consistent with the dispersal of numerous other Old World groups into the New World.
Trachischium monticola, a fossorial, worm-eating natracine
 snake from South Asia
Citation
Peng Guo, Qin Liu, Yan Xu, Ke Jiang, Mian Hou, Li Ding, R. Alexander Pyron, Frank T. Burbrink. 2012. Out of Asia: Natricine snakes support the Cenozoic Beringian Dispersal Hypothesis. Molecular Phylogenetics and Evolution, 63:825-833.