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Snake Venom Tells Tales About Geography

ScienceDaily (July 15, 2008) — Just as people give away their origins by that southern drawl or New England twang, poisonous snakes produce venom that differs distinctly from one geographic area to another, the first study of the "snake venomics" of one of the most common pit vipers in Latin America has found. 

Scientists are reporting that venom of snakes, such as the Bothrops asper from Costa Rica, could differ based on geographical regions, an important finding in the production of antivenom. (Credit: Courtesy of Mahmood Sasa)

 

In the new study, Juan J. Calvete and colleagues point out that researchers have known for decades that venom collected from snakes of the same species from different geographic locations can differ in terms of their biological effects and symptoms on snakebite victims. However, scientists know little about the chemical differences behind these geographically different venoms.

To find out, the scientists collected venom samples from adult and newborn specimens of the lancehead pitviper from two geographically isolated populations from the Caribbean and Pacific regions of Costa Rica. After a detailed laboratory analysis of the proteins found in the venom -- so-called "snake venomics" -- the researchers found major differences in the venoms collected from the two regions.

They also found distinct differences in proteins collected from newborns and adult snakes. The study "highlights the necessity of using pooled venoms as a statistically representative venom for antivenom production" for human snakebite victims, the report states.

Frogs With Disease-resistance Genes May Escape Extinction

ScienceDaily (July 17, 2008) — As frog populations die off around the world, researchers have identified certain genes that can help the amphibians develop resistance to harmful bacteria and disease. The discovery may provide new strategies to protect frog populations in the wild.

As frog populations die off around the world, researchers have identified certain genes that can help the amphibians develop resistance to harmful bacteria and disease. The discovery may provide new strategies to protect frog populations in the wild. (Credit: iStockphoto/Paul Tessier)

 

New research examines how genes encoding the major histocompatibility (MHC) complex affect the ability of frogs to resist infection by a bacterium that is commonly associated with frog population declines.

"In the short term, captive management of frogs with complementary disease-resistance genes may offer the best hope for saving species from extinction," says Bruce Waldman, a biologist at Lincoln University in New Zealand and one of the paper's authors. "Management practices that maintain or enhance diversity in MHC genes may prove the key to safeguarding frog populations in the wild."

"Massive die-offs of frogs may indicate environmental problems that ultimately will affect other species, including humans," Waldman says. "But, despite the concern, little is known about factors that make individuals susceptible to disease."

Doctoral students Seth Barribeau and Jandouwe Villinger, working with Waldman, exposed African clawed frog tadpoles to several doses of the bacterium Aeromonas hydrophila. They examined the number of tadpoles that survived and measured how fast they grew.

Certain genes allowed tadpoles to survive bacterial infection but at a cost, as these tadpoles sometimes grew more slowly. Among siblings, patterns of disease resistance corresponded to tadpoles' MHC genes rather than other genes that they shared, demonstrating that the MHC genes conferred immunity.

Programs currently are underway to rescue frogs from declining wild populations and breed them in captivity to ensure that species are not lost to extinction. This study suggests that selective breeding of individuals with known disease-resistance genes might produce frogs that can survive infection by pathogens, even after the frogs are reintroduced into the wild.

The research team studied the African clawed frog because its immune system already had been well characterized, but as most frogs and toads have similar immune systems, they believe that their results will be generally applicable to all threatened and endangered amphibians.

 

Rescued Sea Turtle, Dylan, Released In Ocean

ScienceDaily (June 30, 2008) — Dylan, a straggler hatchling who was rescued on Jekyll Island almost 10 years ago and became a national ambassador for sea turtles, is going home. Officials from the Georgia Sea Turtle Center on Jekyll Island, and the Georgia Aquarium in Atlanta will release Dylan into the ocean on Monday, June 30th at 11 a.m.

Visitors to Coastal Encounters Nature Center on St. Simons Island, the University of Georgia’s Tidelands Nature Center, the Georgia Aquarium and (most recently) the Georgia Sea Turtle Center have enjoyed the sights of this graceful sea turtle for many years.  Now that her carapace is over 50 cm long, Dylan is big enough to return to the ocean according to standards set by the Georgia Department of Natural Resources.

Since last summer, when Dylan returned to Jekyll Island from the Georgia Aquarium in Atlanta, she has been learning the skills needed to return to the wild - including identifying and capturing natural prey such as blue crabs, horseshoe crabs and whelks.

At 3 p.m. on the day prior to her release, Dylan will also be fitted with a special satellite transmitter, providing Georgia Sea Turtle Center (GSTC) researchers and visitors to the GSTC and Georgia Aquarium Web sites the opportunity to monitor her activities and movements. This will be the first time that a sea turtle has been raised entirely in captivity for this long and then released with a tracking device.  By studying her movements, researchers may be able to learn about some of the differences between learned and inherited behaviors.

“We are very pleased with Dylan’s progress,” said Dr. Terry Norton, Director of Veterinary Services and Interim Director of the Georgia Sea Turtle Center. “She has come a long way in the last year and has been a great representative of sea turtle education and conservation, helping to spread the word about the plight of the sea turtle and the marine ecosystem. We are glad to see her depart for her real home at sea and are excited to watch her travels once she is released."

“The Georgia Sea Turtle Center is an exciting project initiated by the Jekyll Island Foundation and the Jekyll Island Authority. The Center reflects our commitment to conservation, preservation and education.” said William Lattimore, Jr., Chairman of the Jekyll Island Foundation. “This is a very special event for the entire community. Dylan’s release is indeed an appropriate finale for Sea Turtle Weekend, the anniversary celebration of the Georgia Sea Turtle Center.”

After outgrowing her tank at the Tidelands Nature Center in Jekyll Island, a partnership was formed with the Georgia Aquarium, where Dylan was relocated in November 2005. She returned to Jekyll Island in May of 2007, arriving at the Georgia Sea Turtle Center shortly before its official public opening, becoming the second patient.

“The Georgia Aquarium’s partnership with the Georgia Sea Turtle Center has been important and hugely successful,” said Ray Davis, Senior Vice President of Zoological Operations at the Georgia Aquarium. “We loved having Dylan in Atlanta and were sad to see her go, but it is certainly important that she will be released and continues to educate and inspire the future stewards of our oceans.”

The loggerhead sea turtle is threatened worldwide and is under consideration for being reclassified as “endangered” due to diminishing populations in the Western Atlantic Ocean.  Because sea turtles nest on land, responsibility for their conservation is shared between the National Marine Fisheries Service, the U.S. Fish and Wildlife Service and various state agencies and independent conservation organizations

 

Agriculture Linked To Frog Sexual Abnormalities

ScienceDaily (July 5, 2008) — A farm irrigation canal would seem a healthier place for toads than a ditch by a supermarket parking lot.

Giant toad (Bufo marinus) in Tampa Florida. Researchers found that toads in suburban areas are less likely to suffer from reproductive system abnormalities than toads near farms -- where some toads had both testes and ovaries. (Credit: Courtesy of Wikimedia Commons, photo taken by Bill Waller, GNU Free Documentation license)

 

But University of Florida scientists have found the opposite is true. In a study with wide implications for a longstanding debate over whether agricultural chemicals pose a threat to amphibians, UF zoologists have found that toads in suburban areas are less likely to suffer from reproductive system abnormalities than toads near farms -- where some had both testes and ovaries.

"As you increase agriculture," said Lou Guillette, a distinguished professor of zoology, "you have an increasing number of abnormalities."

Guillette is one of several UF authors of a paper on the research appearing in the online version of the journal Environmental Health Perspectives. The lead author is Krista McCoy, who did the work as part of her UF School of Natural Resources and the Environment dissertation.

Several past studies have suggested a link between herbicides commonly used in farming and sexual abnormalities in tadpoles and frogs. Such deformities may be responsible for declines in frogs documented in areas affected by agricultural contaminants, such as Sierra Nevada, Calif., McCoy said. Amphibians are declining worldwide and agricultural chemicals are considered to be one likely cause, she said. Others include pathogenic infections and habitat loss.

Past research has compared frogs collected from natural areas with those collected from agricultural areas. Other efforts have pointed to specific chemicals, including the herbicide Atrazine, as causing abnormalities. The UF study is the first peer-reviewed study to compare abnormalities in wild toads -- toads are a variety of frogs -- from heavily farmed areas with frogs from both partially farmed and completely suburban areas. In so doing, it highlights the difference between the impact of agriculture versus development.

"Our study is the first to explicitly ask, of these two areas of human disturbance, do we see a greater proportion of abnormal animals in one versus another?" Guillette said.

Because the results implicate agriculture, future research can narrow the focus to agricultural chemicals, McCoy said.

"Because we know what chemicals are used at these agricultural sites, we can begin to pin down the chemical cause of these abnormalities by conducting controlled experiments with each chemical alone and in combination," she said.

The researchers gathered giant toads, known scientifically as Bufo marinus, from five sites stretching from Lake Worth to Belle Glade and down to Homestead in South Florida. Bufo marinus is a very large, exotic, invasive, species known to be deadly to small animals. Guillette said the researchers studied the toad in part because they are easy to catch and their large size ensures enough blood for analysis. Also, he said, "they are common in other agricultural areas around the world," which means they are a good generalist species.

One of the sites consisted almost entirely of land devoted to sugar cane or vegetable farms. The amount of farmland declined in three other sites, with the last being entirely suburban. Researchers calculated the amount of farmland in each site using Google Earth images.

Each site was 2.1 square miles, with the toads collected at the center. That's because the toad's home range is known to be about 1.2 miles, and the researchers sought only those toads living entirely within each site. The researchers collected at least 20 toads from each site in 2005 and 2006.

Examination of the euthanized toads revealed a pattern: The more agricultural the land where they lived, the more sexual organ abnormalities or so-called "intersex" toads -- toads who have both female and male internal reproductive organs, not a normal condition for this and most species of amphibians.

While normal male toads' forelimbs are thicker and stronger than those of their female counterparts, more of the intersex frogs only found in agricultural areas had thin, weak forearms. Also, intersexes had fewer "nuptial pads," areas of scrappy skin on their feet used to grip females during copulation.

Where a sex was clear, the male toads appeared by far the most affected. Normal males are brown, while females are mottled with brown stripes. However, males from agricultural areas were mottled, looking like females.

Internally, the more agricultural the sites, the more feminized the males' reproductive organs. Many had both ovaries and testes. Not only that, both the impacted males and the intersex frogs had less of the male hormone testosterone than normal males, suggesting diminished reproductive capabilities, Guillette said.

Guillette and McCoy said the study's results may have important implications not only for other wild species, but also for people.

"What we are finding in Bufo marinus might also occur in other animals, including other amphibian species and humans," McCoy said. "In fact, reproductive abnormalities are increasing in humans and these increases could partially be due to exposure to pesticides."

The paper's other authors are Colette St. Mary, a UF associate professor of zoology; Heather Hamlin, a postdoctoral associate; and Lauriel Bortnick and Chelsey Campbell, who both worked on the study as UF undergraduates.

Malagasy Chameleon Spends Most Of Its Short Life In An Egg

ScienceDaily (July 2, 2008) — There is a newly discovered life history among the 28,300 species of known tetrapods, or four-legged animals with backbones. A chameleon from arid southwestern Madagascar spends up to three-quarters of its life in an egg. Even more unusual, life after hatching is a mere 4 to 5 months. No other known four-legged animal has such a rapid growth rate and such a short life span.

Adult male Labord's chameleon (Furcifer labordi) from Ranobe, Southwestern Madagascar. (Credit: Christopher J. Raxworthy)

"It really is a huge surprise," says Christopher Raxworthy, Associate Curator in the Department of Herpetology at the American Museum of Natural History. "Adding to that, until now, the short life span of chameleons in captivity has always been considered as a failure to thrive. We need to rethink this."

Most mammals, reptiles, birds, and amphibians (all tetrapods) typically live 2 to 10 years, an average bracketed at the upper end by some long-lived animals (for example, turtles and humans that can live for a century) and at the lower end by a handful of animals that only live for about a year.

The males in nine species of marsupials die off after a year, for example, as do most adults in about twelve species of lizards. But the chameleon described here, Furcifer labordi, not only has a brief, yearly life cycle, but the bulk of that time is spent incubating inside an egg. Once outside of the egg, all individuals in the population die within 4 to 5 months.

Kristopher Karsten, a graduate student from the Department of Zoology at Oklahoma State University, discovered the unusual life cycle almost by accident. "I showed up late in the season and found something weird," recalls Karsten. "There were no juveniles. But by February, I found carcasses all over with no signs of mutilation or predation. The population plummeted--we've never seen this with other lizards."

Now, after five seasons of data and sightings of nearly 400 individuals, the life cycle of F. labordi can be described. Hatching begins with the rains in November, and, once emerged, the chameleons develop rapidly, growing up to 2.6 mm (0.1 inches) a day--up to two orders of magnitude greater than other known lizard growth rate. In less than 60 days, for example, there can be a 300%-400% increase in body size for males to reach adulthood. After reaching maturity, the population reproduces, and females burrow through about 138 mm (5.4 inches) of sand to lay their eggs. Once covered, the eggs wait out the dry season for the next 8 to 9 months, and all adults die.

"It is amazing to think that for most of the year, this chameleon species is represented only by developing eggs buried in the ground," says Raxworthy. "This species really illustrates just how much there is still to discover about the natural history of Madagascar." Karsten agrees, adding: "We've identified a species that does something really different from the others, but what is driving this system? One bad year could wipe out these chameleons."

The new research is reported in the June 30 issue of Proceedings of the National Academy of Sciences. The research was carried out by Karsten and Laza Andriamandimbiarisoa of the Département de Biologie Animale, Université d'Antananarivo in Madagascar. Raxworthy and Stanley Fox of the Department of Zoology at Oklahoma State University helped design the study and write the research paper. The project was funded by a National Science Foundation grant to Raxworthy.

 

When Threatened, A Few African Frogs Can Morph Toes Into Claws

ScienceDaily (June 23, 2008) — Biologists at Harvard University have determined that some African frogs carry concealed weapons: When threatened, these species puncture their own skin with sharp bones in their toes, using the bones as claws capable of wounding predators.

Close-up of the foot of a living Trichobatrachus robustus showing the white bony claws protruding from the tips of the toes. (Credit: David C. Blackburn)

The unusual defense mechanism is described by Harvard's David C. Blackburn, James Hanken, and Farish A. Jenkins, Jr., in a forthcoming issue of the journal Biology Letters.

"It's surprising enough to find a frog with claws," says Blackburn, a doctoral student in Harvard's Department of Organismic and Evolutionary Biology. "The fact that those claws work by cutting through the skin of the frogs' feet is even more astonishing. These are the only vertebrate claws known to pierce their way to functionality."

"Most vertebrates do a much better job of keeping their skeletons inside," he adds.

Blackburn first became aware of the clawed frogs while conducting fieldwork in the central African nation of Cameroon. When he picked up one of the hulking fist-sized frogs, it flailed its hind legs violently, scratching him and drawing blood.

Back in the U.S., Blackburn examined museum specimens of 63 African frog species. He noticed that in 11 species -- all in the genera Astylosternus, Trichobatracus, and Scotobleps and all native to central Africa -- the bones at the ends of the toes were pointed and hooked, with smaller, free-floating bones at their tips. Eventually he determined that these small nodules at the tips of the frogs' feet were connected to the rest of the toe by a collagen-rich sheath.

"These nodules are also closely connected to the surrounding skin by dense networks of collagen," Blackburn says. "It appears they hold the skin in place relative to these claw-like bones, such that when the frog flexes a certain muscle in the foot, the sharp bone separates from the nodule and bursts through the skin."

This claw-like structure is no conventional claw, though: It is pure bone, free of the keratin sheath that normally surrounds vertebrate claws. And unlike a claw that retracts into a specialized structure in an animal's foot, as in cats, the site where the frogs' foot bones emerge appears to be covered with ordinary skin.

While these frogs were mentioned in the scientific literature on a few occasions from 1900 to 1925, they are generally little-known in the U.S., appearing in few museum collections. Even the handful of researchers who wrote about them a century ago often misinterpreted the piercing of the skin as damage incurred during preservation of specimens.

The frogs are widely roasted and eaten in Cameroon, where hunters -- evidently well aware of the risk of injury -- go to great lengths to avoid handling them when alive.

"Cameroonian hunters will use long spears or machetes to avoid touching these frogs," Blackburn says. "Some have even reported shooting the frogs."

Of more than 5,500 known frog species, Blackburn and his colleagues found just 11 with claws, and speculate there may be another couple of similarly equipped species.

Blackburn plans to study live specimens of the African frogs to determine whether retraction of the foot bones back into the body is an active or a passive process, and how the damaged skin regenerates after the claws are deployed.

"We suspect, since the frog does suffer a fairly traumatic wound, that they probably use these claws infrequently, and only when threatened," Blackburn says.

Blackburn, Hanken, and Jenkins' work was funded by the National Science Foundation's AmphibiaTree project and by a Putnam Expeditionary Grant from Harvard's Museum of Comparative Zoology.

I will post more credited info, but i just thought it was cool to discover that when ticks, that carry Lyme disease in their gut, feed off of the blood of the Western Fence Lizard (Sceloporus occidentalii) The blood kills off the Lyme disease, and in theory, I think that this could be the reason why there isnt a such an outbreak on the West coast, like there is on the East Coast!

Lizards Pull A Wheelie

ScienceDaily (Jun. 17, 2008) — Why bother running on hind legs when the four you've been given work perfectly well? This is the question that puzzles Christofer Clemente. For birds and primates, there's a perfectly good answer: birds have converted their forelimbs into wings, and primates have better things to do with their hands. But why have some lizards gone bipedal? Have they evolved to trot on two feet, or is their upright posture simply a fluke of physics? Curious to find the answer, Clemente and his colleagues Philip Withers, Graham Thompson and David Lloyd decided to test how dragon lizards run on two legs.

Why bother running on hind legs when the four you've been given work perfectly well? (Credit: Copyright Simon Pynt, Courtesy Dr. C. Clemente)

 

But first Clemente had to catch his lizards. Fortunately Thompson was a lizard-tracking master. Driving all over the Australian outback, Clemente and Thompson eventually collected 16 dragon lizard species, ranging from frilled neck lizards to the incredibly rare C. rubens, found only on a remote Western Australian cattle station. Returning to the Perth lab, Clemente and Withers set the lizards running on a treadmill, filming the reptiles until they were all run-out.

Clemente admits that when he started, he thought that the lizards would fall into one of two groups; lizards that mostly ran on two legs, occasionally resorting to four, and lizards that never reared up. Not so. Even the lizards that he'd never seen on two legs in the wild managed an occasional few steps on their hind legs. In fact, the lizards' propensity for running on two legs seemed to be a continuum; C. rubens and P. minor spent only 5% of the time on their hind legs while L. gilberti spent 95% up on two.

Curious to know whether or not bipedalism has evolved, Clemente drew up the lizards' family tree and plotted on the percentage of time each species spent on their rear legs, but there was no correlation. The reptiles had not evolved to move on two feet. Something else was driving them off their front legs; but what?

According to Clemente, other teams had already suggested reasons for the lizards rearing up; maybe running on two legs was faster or more economical than running on all four. But when Clemente analysed the lizard running footage he realised that running on hind legs was more energetically costly, and the bipedal runners were no faster than the quadrupeds. Knowing that Peter Aerts had suggested that lizards improved their manoeuvrability by moving their centre of mass back towards the hips, Clemente wondered whether the lizards' front legs were leaving the ground because of the position of their centre of mass. Maybe they were 'pulling a wheelie'.

Teaming up with David Lloyd and modelling the running lizards' movements as the lizards accelerated, they realised that there was a strong correlation between the lizards' acceleration and their front legs pulling off the ground. Clemente explains that by moving their centre of mass, a turning force acts on the lizards' torso; lifting it off the ground making them run upright.

So running on two legs is a natural consequence of the lizards' acceleration. Clemente adds that 'some dragon lizards have exploited the consequence and chosen to go bipedal because it gives them some advantage, but we have no idea what that advantage is'.

 

Here is what is supposed to be on the forum (This is only temporally in the blog section until the morning)

Do not worry about the Quiz text under each family below, i am just so tired! lol

First 3 things of this summer’s term

Since we are off to a rough start and waiting on the permission slip from Derek Hall, I have some materials and ideas that we can do! I thought we could begin this class session with learning some scientific names of lizards in by which of memorizing, spelling, and comparing the names with others, as well as, understanding how it can be easy to look at a scientific name that is not familiar to us and being able to narrow down to the common name just a little bit to understand what family or genus it could be from. It will be fun practice as well as building that tool box every herpetologist needs, and you can go to work and impress your co-workers, family members in a conversation!

First assignment will be given this week, and it is an easy assignment. The assignment will be a short essay on what you want to learn about lizards. I will take all submission into an account and will be more than willing to make sure we at least cover something you want to learn. Please use this assignment to your advantage, because after the due date I will bust my behind to try to create a fun, yet learning experience for both the class as a whole and for the individual submission of this assignment. This is due Friday the 20^th of June. And YES I will accept late work on this one!!!

We will be looking at 16 different families of the Lizards. I will be using the ultimate guide to snakes and reptiles, just not copying it word for word, but reading it and typing it in my own words. I just hope you all trust my integrity and if you would like to double check my work, please by all means go out and buy the book for yourself. I will also be using images from the internet in place of what Derek has in his book to represent a clear picture to what you’re reading, plus more photos than what is in the book. Here is the list of families that we are going to look at, and I if you go to the voting polls you can vote on the four I have selected! Also please reply in the HIC group forum under “Families of your pick” so I can feedback on which of the four families you would like to vote on!

Family: Agamidae

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Family: Chamaeleonidae

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Family: Iguanidae

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Family: Gekkonidae

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Family: Pygopodidae

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Family: Teiidae

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Family: Lacertidae

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Family: Xantusiidae

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Family: Scinidae

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Family: Cordylidae

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Family: Dibamidae

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Family: Xenosauridae

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Family: Anguidae

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Family: Helodermatidae

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Family: Lanthanotidae

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Family: Varanidae

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Discussion

Sm. Assignments

Short Testn