Friday, December 31, 2010

More Press on the Oldest Fossil Varanus

I commented on this research back in October. What follows is a press release about the research.

University of Alberta researchers have unearthed a mysterious link between bones of an ancient lizard found in Africa and the biggest, baddest modern-day lizard of them all, the Komodo dragon, half a world away in Indonesia.

Biologists Alison Murray and Rob Holmes say the unique shape of the vertebrae links the 33-million-year-old African lizard fossil with its cousin the Komodo, which has only been around for some 700,000 years.

"The African fossil was found on the surface of a windswept desert," said Holmes. "It's definitely from the lizard genus Varanus and there are more than 50 species alive today, including Komodos and other large lizards."

Holmes says the telltale African vertebrae fossils belonged to a lizard that was about a metre- and-a-half long whose ability to swim may be key to figuring out how more than 30 million years later its ancestors turned up on the other side of the world.

Holmes says the ancient African Varanus specimen was found on land that was once the bottom of a river or small lake. "Whether the animals lived in the water or surrounding land, we don't know, but we do know that some modern day species of Varanus are comfortable swimming in fresh water."

The researchers agree that fresh-water swimming wouldn't get the African lizard all the way to Indonesia. Murray says the mystery of how the animals spread deepens when you consider ancient world geography. "From about 100 million years ago until 12 million years ago, Africa was completely isolated, surrounded by ocean, but somehow they got out of Africa during that period," said Murray. "That's why this paper is important because there was no known land connection."

Murray says one unproven theory of how Varanus moved out of Africa is that over millions of years, small land masses or micro-plates may have moved from one place to another, carrying their fauna with them.

The work of the U of A researchers and various co-authors runs counter to some prevailing theories about the origins of some ancient fossil types found in Africa including Varanus lizards and some fresh-water fish. "The assumption for several types of ancient African fossils is that the animals didn't originate in Africa but came there from Asia," says Holmes. "But the fossil record of Varanus shows exactly the opposite path of migration."

Citation
Robert B. Holmes, Alison M. Murray, Yousry S. Attia, Elwyn L. Simons, Prithijit Chatrath. 2010. Oldest known Varanus (Squamata: Varanidae) from the Upper Eocene and Lower Oligocene of Egypt: support for an African origin of the genus. Palaeontology, 53(5):1099 DOI: 10.1111/j.1475-4983.2010.00994.x

Roger Repp Reports on a Recent Field Excursion to Ragtop in Southern Arizona

Howdy Herpers,

Fat, dumb and happy here is busily gathering herp numbers for the year 2010 for the Sonoran Herpetologist. I have one last outing to pull off-- that will be tomorrow.

I don't expect that effort to change the fact that 2010 has been by far the WORST herping year of the Y2K century. There are likely many factors involved as to why, but I do think the nonsoon season of 2009 played a big role.

By the way, a fair number of you pulled a wuss on this upcoming adventure tomorrow. Well, Annamarie Saenger didn't. What will see at 0 degrees C you ask? Oh, probably three to four Gila Monsters, the same number of tortoises, about a dozen rattlesnakes, hopefully a couple chuckwallas. That all depends on how fast we can
cover known ground.

On 2 December of this year, I made a pilgrimage to Ragged Top. The place used to be the best, but the drought of 1996 nearly wiped the place clean of herps.

We'll let the pictures tell the rest of the story:

Pic 1: The place.

Pic 2: In December 2009, a tortoise was viewed deep in a burrow that was the home of tortoise #26 back in 1995. I rejoiced to see a tortoise there again. Well, on 2 December 2010, this is what I saw at the mouth of the burrow
entrance. Good old Ragged Top--burial ground of tortoises great and small.

Pic 3: From 1994 through 1997, just above the burrow of tortoise 26, a large adult chuckwalla was using a crevice. On 2 December 2010, this one was in the crevice. While it is not the same chuck, it is good to know that one has
zeroed in on the haunts of the other. It gives me a reason to go back.

Pic 4: Good news! The chuck #26's inner plumbing is still working!

Pic 5: The white rocks chuck crevice. A chuck or chucks have been using this formation as a hibernacula since 1992! 2 December 2010 was no different.

Pic 6: Photo by Hans-Werner Herrmann. Taken in January 2009. This same bob-tailed chuckwalla used the white rocks crevice then, December 2009, and again in December 2010. I hope we can make it back to the place tomorrow.

I hope that you all had a GREAT holiday season. Wishing you all a
happy new year as well.

Best to all, roger

Wednesday, December 29, 2010

Species Diversity, Geographic Area, and Anolis

 There are more than 377 species of Anolis scattered around the Western Hemisphere's tropic and subtropical areas. There are very few land masses in these regions that lack Anolis.The new work by Rabosky and Glor with Anolis confirms the relations between geographic area and the number of species present, idea proposed by E. O. Wilson and Robert MacAurthur a half century ago.


 The following is a press release from the University of Rochester.

Research Shows that Environmental Factors Limit Species Diversity

It's long been accepted by biologists that environmental factors cause the diversity—or number—of species to increase before eventually leveling off. Some recent work, however, has suggested that species diversity continues instead of entering into a state of equilibrium. But new research on lizards in the Caribbean not only supports the original theory that finite space, limited food supplies, and competition for resources all work together to achieve equilibrium; it builds on the theory by extending it over a much longer timespan.

The research was done by Daniel Rabosky of the University of California, Berkeley and Richard Glor of the University of Rochester who studied patterns of species accumulation of lizards over millions of years on the four Caribbean islands of Puerto Rico, Jamaica, Hispaniola, and Cuba. Their paper is being published December 21 in the journal, Proceedings of the National Academy of Sciences.

Glor and Rabosky focused on species diversity—the number of distinct species of lizards—not the number of individual lizards.

"Geographic size correlates to diversity," said Glor. "In general, the larger the area, the greater the number of species that can be supported. For example, there are 60 species of Anolis lizards on Cuba, but far fewer species on the much smaller islands of Jamaica and Puerto Rico." There are only 6 species on Jamaica and 10 on Puerto Rico.

Ecologists Robert MacArthur of Princeton University and E.O. Wilson of Harvard University established the theory of island biogeography in the 1960s to explain the diversity and richness of species in restricted habitats, as well as the limits on the growth in number of species. Glor said the MacArthur-Wilson theory was developed for ecological time-scales, which encompass thousands of years, while his work with Rabosky extends the concepts over a million years. "MacArthur and Wilson recognized the macroevolutionary implications of their work," explained Glor, "but focused on ecological time-scales for simplicity."

Historically, biologists needed fossil records to study patterns of species diversification of lizards on the Caribbean islands. But advances in molecular methodology allowed Glor and Rabosky to use DNA sequences to reconstruct evolutionary trees that show the relationships between species.

The two scientists found that species diversification of lizards on the four islands reached a plateau millions of years ago and has essentially come to an end.

Glor said the extent and quality of the data used in the research allowed him and Rabosky to show that species diversification of lizards on the islands was not continuing and had indeed entered a state of equilibrium.

"When we look at other islands and continents that vary in species richness," said Glor, "we can't just consider rates of accumulation; we need to look at the plateau points."

Glor emphasizes that a state of equilibrium does not mean that the evolution of a species comes to an end. Lizards will continue to adapt to changes in their environment, but they are not expected to develop in a way that increases the number of species within a habitat.

Glor believes his work with Rabosky represents the "final word" on the importance of limits on species diversity over the rate of speciation when explaining the species-area relationship in anole lizards.

Citation
Rabosky D. L. and R. E. Glor. 2010. Equilibrium speciation dynamics in a model adaptive radiation of island lizards. Proceedings of the National Academy of Science 107(51): 22178-22183; doi:10.1073/pnas.1007606107

Tuesday, December 28, 2010

Sand Swimming in Scincus scincus

Sand swimming is a specialized locomotion used by several species of lizards and snakes. The following was posted on the Physics Central website. Be sure to visit the website and view the videos that include a Sandfish (Scincus scincus, Family Scincidae) swimming through sand.

Swimming through sand: The secret of sandfish locomotion
Monday, December 27, 2010
We know how airplanes glide in the air and how submarines move through water, but we don't know much about how creatures "swim" through sand. 'Til now...

How an object's shape affects its generation of lift and drag in both the air and in water is well understood. Otherwise, we'd be misplacing submarines all the time. But how objects - animals in particular - create lift and drag in granular materials like sand is less well understood.

A couple of Ph.D. students and their professor have been taking a closer look at what happens when sand-dwelling creatures - like lizards, crabs, snakes and worms - dive below the surface.

Yang Ding and Nick Gravish, along with Daniel I. Goldman, their Georgia Tech professor of physics, have been studying the sandfish lizard, a popular sand-dwelling pet, to see how it maneuvers in its subterranean environment.

Goldman described the sandfish as a little lizard that lives in the desert in North Africa. When startled, it can burrow 10 cm beneath the surface in less than half a second. Its wedge-shaped head, which biologists believe gives the critter its lightning-quick burrowing ability, was the project's inspiration.

"We think the sandfish is the champion of rapid burial," Goldman said.

Another thing the trio noticed about the lizard, Ding said, is that its belly is really flat. "We thought that might have an effect," he said.

To test the theory on both the head shape and the belly, the team dragged three objects of different shapes through a container filled with tiny glass beads that acted as a sand analogue. They watched to see whether each object generated any lift - the force perpendicular to the direction of motion that "pushes" an object up.

The first was a cylinder. The team dragged it horizontally through the beads (if it were a Coke can, it would have been dragged from the dash in between the words "Coca" and "Cola") and measured the forces acting on it.

The cylinder experienced positive lift; it tended to rise within the beads, headed for the surface. A square rod was also dragged through the beads and it, too, rose towards the surface, but just barely. The third object was a half-cylinder. It experienced negative lift, sinking lower into the beads as it was dragged along.

Of the three objects, the half-cylinder most approximates the shape of the sandfish lizard's head. Since the lizard also experiences negative lift when it enters the sand, the lab test showed that the half-cylinder was a good starting point for modeling the lizard's head.

The researchers then dragged flat plates through the sand. The plates were given roughly the same angle of attack - or angle away from horizontal - as the leading edge of each of the objects. To mimic the cylinder, the first plate was at a very small angle almost perpendicular to the floor. Just as for the cylinder, the plate experienced positive lift.

The plate was then dragged forward at a 90 degree angle relative to the floor, and again, as with the cube-shaped rod, there was next to no lift. Then the plate was dragged at a wide angle, leaning back from the direction of motion like a lawn chair leans back from the surf at the beach. This time, as with the half-cylinder, there was negative lift.

These were exciting results for the researchers because they realized that they could break up the shape of any object into flat plates and sum them up in a computer model to see the forces acting on any object. In addition to showing lift, the models also helped them to understand how much drag, or force acting opposite the direction of motion, "tugging" on an object, was being produced.

"We found that we can basically understand the forces by decomposing them in flat plates," Gravish said. "You can build whatever object you want to see what forces it undergoes in granular materials."

A database of how objects respond when traveling through granular materials can be created simply by finding the sum of simple materials - the plates. Since there are no equations to describe locomotion in granular materials, the find was particularly exciting.

"What you really want to do in all this business is figure out the principles of what's going on," Goldman said. The results of this research have opened the door for the physicists to do just that.

On an earlier research project, Goldman's CRAB Lab used high-speed x-ray imaging to observe the lizard's movement when submerged. They found that it doesn't use its legs when swimming through sand, instead tucking them by its side and slithering like a snake.

Using the data garnered from watching lizards swim and the new lift and drag research, the CRAB Lab got down to serious business and built a sandfish lizard robot they hope to debut at the 2011 International Conference on Robotics and Automation. They envision creating a rubble-swimmer that could aid with search-and-rescue missions after disasters like the earthquake in Haiti or the 9/11 collapse of the Twin Towers.

Ding, Gravish and Goldman's paper, "Drag induced lift in granular media," is due to appear in Physical Review Letters Dec. 31.
Posted by Echo Romeo




Monday, December 27, 2010

Bangladesh Government Plans to Export Snake Venom

bdnews24.com is reporting the following story, it is unedited.  
Mon, Dec 27th, 2010 9:49 pm BdST
by Mohsinul Karim
Dhaka, Dec 26 (bdnews24.com)—Bangladesh is taking initiatives to export snake venom, a high-priced product in the international market.

The fisheries and livestock ministry has called a meeting of experts on Jan 2 to launch a project to this end.

Fisheries minister Abdul Latif Biswas told bdnews24.com on Sunday that Bangladesh, like the neighbouring countries, will be farming snakes under the project to collect large quantities of venom for sale abroad.

He added that the project would also create employment opportunities for snake-charmers and other related poor people.

Ministry officials said that India, Thailand and China earn large amount of foreign currency through venom exports and that they had several government and private-run venom production facilities.

Momtaz Begum MP raised the issue in parliament recently and her proposal was supported by prime minister Sheikh Hasina and the minister.

The Export Promotion Bureau took steps in this regard in 2007.

Ministry officials added that the Bangladesh Livestock Research Institute (BLRI) had already submitted a report of their preliminary survey and review.

BLRI director general Shahidul Huq told bdnews24.com: "The report proposed nurturing a variety of snakes, although initially venom would be collected from a single variety. We also proposed that nurturing vipers would be profitable."

He went on to say that 500 snakes will have to be nurtured for a year to collect 100 grams of dry venom and pointed out that the ratio varies upon the species.

Minister Biswas said his ministry was already discussing ways to implement the project.

"Snake venom is used to manufacture various drugs and is sold in the international market at $200-$2000 per gram. Snake venom export could contribute greatly in the development of the economy," he added.

According to him, the neighbouring countries export around five tonnes of venom every year.

Biswas said there are several types of venomous snakes in the country.

"Snake-charmers have no idea about the extent of the financial value of venom. They capture snake to entertain people and earn money."

The ministry's deputy secretary Rafiqul Islam said the project's implementation was still in a preliminary stage and that zoology and toxicology experts of universities and medical colleges are working on it.

"We are discussing the advantages and disadvantages of its implementation with them."

bdnews24.com/mk/dd/ra/ost/rn/am/1959h

Sunday, December 26, 2010

Is DEET Toxic to Anacondas?

The following is a news article from the Telegraph. This is one story I am more than a bit skeptical about. DEET is N,N-Diethyl-m-toluamide and Google searches in Scholar do not return articles that link this molecule with toxicity in reptiles. If anybody knows about this please let me know. I have no doubt DEET is toxic to snakes at some level. However, it is difficult for me to believe that it is killing anacondas in the concentrations that the snakes would be exposed to from being near tourists. It seems to me an other cause of the snake mortality will be found once it is investigated. JCM The story that follows is unedited.

World's biggest snake threatened by backpackers
The lure of seeing the anaconda in its natural habitat is bringing thousands of British backpackers to a small corner of the Amazon that has become one of the continent's biggest eco-tourism destinations.
By Michael Howie, La Paz 4:47PM GMT 21 Dec 2010

But for the anacondas that live in the swamps surrounding the Yacuma River in northern Bolivia, this invasion of gap year travellers and other hardy tourists is proving disastrous.

Biologists say the entire population of anacondas in one of the jewels of the Amazon basin will be wiped out within three years because of the deadly effect on the snakes of the insect repellant used by most backpackers to help protect against malaria.

The number of tourists going on tours of the pampas that snake there way through jungle and grasslands 250 miles north of La Paz has exploded from a few hundred to nearly 12,000 a year in the past decade.

Travellers are enticed by the promise of getting up close and personal with the world's largest snake - sometimes picking them up and hlding them - as well as swimming with river dolphins, catching pirhanas, and spotting monkeys, sloths and an array of other flora and fauna.

But sightings of the snake are becoming increasingly elusive and as many as 30 of the awe-inspiring creatures, which can measure up to 30ft in length and are known to strangle and devour prey as diverse as caiman crocodiles and cows, are being found dead every year, according to local guides.

Roberto Justiniano, a tour guide and biologist working closely with other scientists to assess the impact of the unrestrained tourism boom, revealed that the growing quantity of toxins being washed into the waterways from travellers is proving too much for the anacondas.

"The high-strength insect repellant that tourists use to protect themselves from mosquitos is absolutely fatal to the anacondas.

"They are amphibians and breath through their skin. The insect repellant, along with some types of sun cream, is extremely toxic. It is getting washed into the pampas and left in the swamps where tourists are hunting for the snakes.

"We are finding between 25 and 30 dead anacondas which have been poisoned. It is terrible."

Amphibians, such as snakes and frogs, are highly susceptible to the chemicals contained in many types of insect repellant, in particular those that contain DEET. This is partly because they breathe and absorb water through their skin, providing an easier way for contaminants to enter the animal's body. Environmentalists recommend using safer insect repellants based on natural oils, but many tourists complains these are less effective.

Zoologists estimate that only around 200 anacondas remain in the Yacuma River swamps, a sharp fall from the population of nearly 1,000 a few years ago.

"A few years years ago you had a 90 per cent chance of seeing anacondas - maybe three or four together. Now you are very lucky if you see one."

He added: "A study has been carried out by other biologists which shows the ecosystem will collapse in three years if things continue as they are."

The fear is that insects, fish and smaller amphibians would be wiped out within the river basin, resulting in the collapse of the entire food chain.

Mr Justiniano, who has guided tours of the pampas for four years, blames uncaring tour agencies and the carefree attitude of travellers who come to experience this once untouched natural wilderness.

"People come to be entertained by the natural world, to touch and play with the animals. This is wrong, we have to have more respect," he said.

He is now striving to set up an association of tour agencies to protect the wildlife. A proposed code of conduct would encourage tourists to use only eco-friendly insect repellant and set a cap on visitor numbers.

"During the 1990s only a few hundred people came here. Now we have had 35,000 in total over the last three years, many of them from Britain. The tourism at this moment is completely unsustainable for this beautiful environment," he said.

Anacondas, which are native only to the Amazon basin, are already in increasing danger from loss of habitat due to deforestation.

Mr Justiniano says the snakes continue to thrive in more remote parts of Amazonian Bolivia where tourism has not yet penetrated, but fears that could change as the growing number of travellers encourages tour operators to sell packages further afield.

His fears about anacondas and the rest of the wildlife in the pampas are backed by Conservation International Bolivia, which says tourism is having a "major negative effect" on the ecosystem which the snakes rely on.

Candido Pastor Saavedra, the body's director of programmes, told The Sunday Telegraph that while the invasion of tourists provided an economic boon to relatively poor communities, the anacondas were paying heavily. Water used for washing and showers was returned to the waterways, he said, carrying insect repellant and other chemicals with it.

"In the pampas of the Yacuma, the quantity of tourists has increased so much that there is a negative effect. This is a result of practices such as the manipulation of animals like the anacondas, discharging service water into the river or dumping waste.

"These bad practices must be corrected or we will end up killing the goose that lays the golden egg," he said.

Most backpackers are oblivious to the devastating impact their presence is having for the anacondas.

Roberta Spence, 23, from London, who quit her accounting job to go travelling, was among a group of English backpackers about to go looking for the snake.

"I didn't know they were getting harder to find," she said, as she prepared to head out with her guide. "I really want to touch one. It's very exciting. It's a shame if they are dying out. No-one at the agency told us about this."

Nicola Smith, 22, from Bristol, added: "They advertise the trips as a chance to find anacondas, which was the main reason I wanted to come. But I haven't met anyone who's actually found one yet. It's sad to think they are suffering because of us.

"But I'm not sure I would stop using insect repellant. I don't want to get malaria."

USFWS Proposes Dunes Sagebrush Lizard Endangered

An edited press release.

The U.S. Fish and Wildlife Service (Service) took action today (December 15, 2010) to protect the Dunes Sagebrush Lizard (Sceloporus arenicolus) by proposing it as endangered under the Endangered Species Act (ESA). The Service has also determined that critical habitat for the dunes sagebrush lizard is prudent — but not determinable — at this time. A 60-day public comment period will begin upon publication of this proposal in the Federal Register.

The ESA provides a critical safety net for America’s native fish, wildlife and plants. This landmark conservation law has prevented the extinction of hundreds of imperiled species across the nation and promoted the recovery of many others. The Service has found that the Dunes Sagebrush Lizard is presently in danger of extinction throughout its entire range, based on the immediacy, severity, and scope of the ongoing significant threats of habitat loss and fragmentation.

The Dunes Sagebrush Lizard faces immediate and significant threats due to oil and gas activities, and herbicide treatments. The species is highly restricted in its range, and the threats occur throughout its range. Habitat loss and fragmentation due to oil and gas development is a measurable factor impacting the species due to the removal of shinnery oak and creation of roads and pads, pipelines, and power lines.

The Dunes Sagebrush Lizard, found in southeastern New Mexico and adjacent west Texas, is a small, light brown lizard with a maximum snout-to-vent length of 2.8 inches for females and 2.6 inches for males. This lizard is a habitat specialist native to a small area of shinnery oak dunes extending from the San Juan Mesa in northeastern Chaves County, Roosevelt County, through eastern Eddy and southern Lea Counties in New Mexico. In Texas, the dunes sagebrush lizard is found in a narrow band of shinnery oak dunes in Gaines, Ward, Winkler, and Andrews Counties.

The Service is requesting comments or information from the public, other concerned governmental agencies, Native American Tribes, the scientific community, industry, or any other interested parties concerning this proposed rule. The agency will consider comments received or postmarked on or before February 14, 2011. Also, the Service must receive requests within 45 days for public hearings, in writing, at the address shown below by January 28, 2011. More information is available online at http://www.fws.gov/southwest/.

Thursday, December 23, 2010

Horned Lizard Research and Observations


Phrynosoma modestum, JCM
The Phrynosomatidae, is a group of iguanian lizards that range from Canada to Panama and contains some of the most familiar saurians in North America, including: the spiny lizards (Sceloporus), horned lizards (Phrynosoma), and side-blotched lizards (Uta). The family contains nine genera (ten genera if the genus Sator is recognized separately from Sceloporus) and more than 136 species. Weins et al. (2010) used molecular techniques to show that phrynosomatids are divided into two major clades the Phrynosomatinae and Sceloporinae. Phrynosomatinae contains the horned lizard clade Phrynosoma and the sand lizard clade (Callisaurus, Cophosaurus, Holbrookia, and Uma).

Skull of a Phrynosoma with spiny processes.JCM
Horned Lizards of the genus Phrynosoma are remarkably cryptic. Their dorso-laterally flattened bodies, tan and brown coloration and spine covered heads and bodies make them exceptionally difficult to find. The spine covered heads and bodies of these lizards undoubtedly serve as a deterrent to predators, but horned lizards also eat ants and store the noxious formic acid from the ants in their blood. Yet some predators are able to deal with the spines and chemicals. O’Connor, et al. (2010) report finding an adult female Great Basin Nightsnake (Hypsiglena chlorophaea deserticola) in Kittitas County, Washington that regurgitated a half-digested adult male Pygmy Short-horned Lizard (Phrynosoma douglasii) estimated to be about 41 mm SVL and 6 grams. The snake's mass was estimated to be just over 12 g. so the predator-prey mass ratio was about 0.50.

Lahti, et al. (2010) found Phrynosoma (Tapaja) douglasii inhabiting 3 distinct microhabitat types (lithosol, loamy, and ecotone) within the shrub-steppe of central Washington’s Quilomene Wildlife Area. The study site had been used for grazing until 1979, and fires were minimal in the last 30 years. June and July were the peak activity months for lizards. Most lizards were encountered in lithosol (61%), a habitat with sparse vegetative cover and weathered fragments of rock; followed by ecotone (31%); and loamy (8%) microhabitats. Lizards, particularly those inhabiting lithosol microhabitats, did not usually retreat to shrub cover until approached within 1 m. While horned lizards are considered low-density species relatively high population densities have been reported for Phrynosoma (Tapaja) douglasii (14.3 to 14.6 lizards/ha in eastern Idaho). However, the authors report a density of about 2 lizards per hectare at their study site, a density that is more characteristic of that reported for other Phrynosoma species. Neonates were almost always encountered closest to Thymeleaf Buckwheat and would often retreat toward the plant when approached. Thymeleaf Buckwheat has the smallest and most compact growth form of any perennial plant at Quilomene Wildlife Area. In contrast, adults would usually retreat to either Stiff Sage or Rock Buckwheat, both of which are larger. The authors conclude that Phrynosoma (Tapaja) douglasii occurs at low densities in the shrub-steppe of Washington where females are larger and more abundant than males, neonates are rare, and reproductive output is low. Younger lizards maintain activity into hotter periods and remain active later in the activity season than do adults, a trait likely related to the importance of garnering sufficient energy to emerge in good condition after a long winter. While this species is most commonly encountered in shrub-steppe habitats, it shows considerable spatial and seasonal variation in the use of microhabitats.

Hellgren et al. (2010) describe the effects of rotational livestock grazing and prescribed winter burning on the resources and survival of the Texas Horned Lizard (Phrynosoma cornutum) in southern Texas. Winter burning provided an increase in food resources and led to increased survival rate in the second growing season after fire. However, grazing-induced changes in vegetation cover reduced survival, probably by increasing lizard vulnerability to predation. Fire and grazing reduced litter, increasing open ground and forb cover but did not alter woody vegetation. Ant activity was greater in burned sites and varied with grazing level, season, and year. Higher survival observed on burned sites in the second year after burning. Survival rates were ordered from highest in un-grazed sites to lowest in heavily grazed sites.

In three papers Cooper and Sherbrooke (2010a,b,c) investigated anti-predator behavior in the Round-tailed Horned Lizard (Phrynosoma modestum) and the Texas horned lizard (Phrynosoma cornutum). They (Cooper and Sherbrooke, 2010a) investigated the effects of repeated attacks by a predator on the Texas Horned Lizard, P. cornutum, and the opportunity cost of fleeing during a social encounter in P. modestum. The results suggest flight initiation distance was greater the second time a predator approached and probability of fleeing decreased as the distance between the predator and prey increased, but was greater when the predator turned toward than away from a lizard. The flight initiation distance was shorter during social encounters than when lizards were solitary. It appears that risk assessment by horned lizards conforms to the predictions of escape theory and is similar to that in other prey despite their specialized defenses. The results suggest that escape theory based on costs and benefits applies very generally, even to highly cryptic prey with specialized defense mechanisms.

In a second paper, Cooper and Sherbrooke (2010b) note that Phrynosoma modestum is eucryptic in that it resembles small stones and the authors predicted that flight initiation distance by P. modestum is shorter among stones than on uniform sand and that flight initiation distance is greater after movement and when standing than when still and lying on the ground.  Movement and upright posture disrupt crypsis in this lizard. The authors measured running speed and flight initiation distance to determine relationships among body temperature, speed, and escape decisions. Running speed and flight initiation distance were reduced at lower body temperature, suggesting that crypsis reinforced by immobility is more advantageous than longer flight initiation distance for cool, slow lizards. Thus, the Round-tailed Horned lizard adjusts its escape decisions to the current effectiveness of crypsis and escape ability.

Cooper and Sherbrooke (2010c) found that Texas horned lizards (Phrynosoma cornutum) would take flight sooner when approached rapidly rather than slowly and when approached directly rather than indirectly. They also found  P. cornutum were much more likely to move and jump when a model predatory bird passed overhead and cast a direct shadow on them as opposed to casting a shadow near the lizard. They suggest P. cornutum assess themselves as being in immediate peril when suddenly covered by a shadow. So, while the Texas Horned Lizard relies heavily on crypsis, they make escape decisions based on the degree of predation risk.

Literature
Cooper, W. E. and W. C. Sherbrooke. 2010a. Plesiomorphic Escape Decisions in Cryptic Horned Lizards (Phrynosoma) Having Highly Derived Antipredatory Defenses. Ethology, 116: 920–928. doi: 10.1111/j.1439-0310.2010.01805.x
Cooper, W. E. and W. C. Sherbrooke. 2010b. Crypsis influences escape decisions in the Round-tailed Horned Lizard (Phrynosoma modestum). Canadian Journal of Zoology, 88:1003-1010.
Cooper, W. E. and W. C. Sherbrooke. 2010c. Initiation of Escape Behavior by the Texas Horned Lizard (Phrynosoma cornutum). Herpetologica 66:23-30.
Hellgren, E. C., A. L. Burrow, R. T. Kazmaier, and D. C. Ruthven. 2010. The Effects of Winter Burning and Grazing on Resources and Survival of Texas Horned Lizards in a Thornscrub Ecosystem. Journal of Wildlife Management 74(2):300-309.
Lahti, M. E., D. D. Beck, and T. R. Cottrell. 2010. Ecology of the Pygmy Short-Horned Lizard [Phrynosoma (Tapaja) douglasii] in Washington. Northwestern Naturalist 91(2):134-144.
Montanucci, R.R. 2004. Geographic variation in Phrynosoma coronatum (Lacertilia, Phrynosomatidae): further evidence for a peninsular archipelago. Herpetologica 60 (1): 117-139
O'Connor, A. P., J. L. Wallace, R. E. Weaver, and M. P. Hayes. 2010. Pygmy Short-Horned Lizard (Phrynosoma douglasii): Unrecorded Prey for the Great Basin Nightsnake (Hypsiglena chlorophaea deserticola).  Northwestern Naturalist 91(1):79-81.
Wiens , J. A., C. A. Kuczynski, S. Arif , and T. W. Reeder. 2010. Phylogenetic relationships of phrynosomatid lizards based on nuclear and mitochondrial data, and a revised phylogeny for Sceloporus. Molecular Phylogenetics and Evolution 54:150–161

Wednesday, December 22, 2010

The Salamander and the Rockslide

 Photo Credit: Arie van der Meijden.
Charles Camp described the Mount Lyell Salamander, Spelerpes platycephalus, in 1916 from specimens he collected at the head of Lyell Canyon, about 10,800 ft above sea level in Yosemite National Park. He described the habitat as at the upper edge of the Hudsonian life-zone. Two specimens were taken in a patch of heather among the rocks where water was flowing beneath the surrounding snowbanks. Today the Mount Lyell Salamander is know to have a wide distribution in the Sierra Nevada's from elevations of 1220 to 3660 meters above sea level. Stejneger and Barbour (1917) considered it to be in the genus Eurycea, but in 1923 Dunn placed it in Hydromantes, a genus erected by Gistel in 1848. Today Hydromantes contains three species, all are endemic to California. H. platycephalus inhabits exposed granitic rock outcrops, talus, and rock fissures, near seepages from streams or melting snow, and it has also been found in the spray zone of waterfalls. Eggs are thought to be deposited in terrestrial situations such as cracks and crevices below the surface in moist or wet limestone talus or in other subterranean cavities - they remain undiscovered. Eggs are also thought to undergo direct development because its close relatives undergo direct development. This is a cold-tolerant species, with body temperatures reported to be as low as -2.0 ˚C to 11.5 ˚C, but laboratory specimens preferred 13–14 ˚C (Brattstrom, 1963).

Today, a Yosemite National Park population of Hydromates platycephalus is part of a battle of conflicting interests involving traffic, ecotourists, and a landslide. There is a one-lane bridge over the Merced River with traffic lights on each end which alternate in a cycle that lasts several minutes, the westbound traffic is allowed through, then eastbound. It's a slow process that results in lengthy delays, and could be vulnerable to floods. The reason for the traffic bottleneck is a landslide that occurred five years ago on Highway 140. An estimated 800 million tons of rocks and debris blocked the road and forced tourists from the San Francisco Bay area to take hours-long detours to reach the valley. Engineers responded quickly and installed a temporary solution. But a longer-term fix has proven more difficult. One solution involves installing a cement bridge, but that's clearly inappropriate for a national park since it would spoil the natural surroundings. Another possibility is to build  two viaducts, but that would destroy a wildflower area. A third solution would be to tunnel under the landslide, but the Mt. Lyell Salamander inhabits the rockslide and construction could destroy it. Finally, the current situation could be kept as is as long as the existing road does not wash out in a flood (Baume, 2010; Burke, 2010).

Tuesday, December 21, 2010

A Different Point Of View: Ontario's Fox Snake Restoration Program

The following commentary presents a different, but familiar point of view, regarding taxes spent on conservation projects. This view point is always interesting to me because it is so different than mine. Be sure to follow the link at the bottom and read the comments, some are interesting. Some background: The Eastern Fox Snake (Pantherophis gloydi) is considered threatened provincially and nationally in Canada. It is thought to have declined in Ontario as wetlands were drained and shorelines were developed for cottages. It is protected under Ontario's 2007 Endangered Species Act but it is also protected in two National Parks, and 16 Provincial Parks and Nature Reserves. In Ontario, this species is also protected under the Fish and Wildlife Conservation Act.  

Vander Doelen: Millions spent on snake housing
Did you know that the endangered eastern fox snake can climb like a monkey?
Well, not exactly like a monkey. Although rather talented for a snake, the eastern fox is a little short on fingers. But the remarkable fact that a two-metre-long snake native to Canada can climb at all means that the new Windsor-Essex Parkway, when completed, will be protected on both sides by more than 22 kilometres of snake-proof fencing.

The fence will be nearly two metres tall itself, and its bottom edge will be buried two feet deep because the wily fox snake burrows even better than it climbs.

The fences will be there entirely for the protection of the snake, however, rather than squeamish drivers who might be creeped out by seeing such a large reptile sunning itself on the road, as they like to do.

The plan is to prevent the handsome spotted devils from straying onto the six-lanes of concrete pavement, where they would become snake pizza.
Protecting the eastern fox snake and other seldom-seen species of flora and fauna along the 11-kilometre route of the new parkway will account for a significant chunk of the $2.2 billion Ontario intends to spend to build and maintain the highway over the next 30 years.

News of the snake-proof fence was among the project details revealed last week by provincial bureaucrats who've been planning the international highway link for the last five years. In addition to the fences, accredited herpetologists have been seconded to the project from other ministries, or hired on as consultants.

There won't be any full-time snake wranglers on site during construction, per say. But enough snake-spotting training will be provided for all the staff -- from supervisors to heavy equipment operators -- that by the end of the three years of work the province will be able to boast truthfully that no snakes were carelessly harmed during the building of the project.

And don't think they won't boast. If there's one thing we know for certain about Premier Dalton McGuinty's Liberals is that they define themselves by their green credentials, no matter how much they cost taxpayers.
Officials sent to Windsor to release further details of the project last week weren't able to provide us with estimates of the environmental protection costs embedded in the project, but they are certain to run into millions. Perhaps tens of millions.

"We can't kill anything," says Fausto Natarelli, the senior Ministry of Transportation official running the project. "We're going to extraordinary measures because it's the right thing to do."

As a nature lover myself -- including the half dozen snake species which share our woodlot near Harrow -- I'm glad the province is spending my money to avoid unnecessarily killing these creatures.

I'm a little less convinced of the need to protect five species of so-called "endangered" wildflowers and trees which have been identified along the 11-kilometre route.

These plants are rare only in Canada. Utterly common in warmer U.S. climes, their survival as a species wouldn't be threatened by the parkway project even if every one of them was buried under a metre of concrete.
But they've already started marking some of them for relocation, if you've noticed all the pretty pink tape dotting the ditches along Talbot Road.

By next summer, hundreds of plants will have been transplanted to the parks and nature reserves which dot the west end of the city.

The species involved include the fabulous dense blazing star, a one-metre-tall perennial weed of dazzling purple magnificence which I intend to find for our own gardens, now that I know what it looks like. Other species to be relocated include the colic root (sometimes called the wild native yam), and the Kentucky coffee tree, a large hardwood with a deep tap root which will be tough to move unless they find small specimens.

They have until the fall of 2011 to find new homes for the "dislocated" species. Although design work is well underway, little of the three million cubic metres of dirt which has to be moved for the project will be disturbed until late next summer at the earliest, officials say.

Before then, biologists will recreate "hibernacula," or winter hibernation burrows, in nearby nature reserves for the 100-odd eastern fox snakes known to occupy the site.

You heard that right. In McGuinty's Ontario, we even build government housing for snakes. Maybe it's best I don't know how much of our money they're spending. I'm already irked enough by the hydro bills.

Read more: http://www.windsorstar.com/technology/Vander+Doelen+Millions+spent+snake+housing/4006375/story.html#ixzz18n3n4h1M

Hanoi's Giant Softshell Faces an Invasive North American Turtle


Rafetus swinhoei Photo Credit:
Asian Turtle Conservation Network
Turtles have cultural importance in the societies of Southeast Asia. In Vietnamese culture the Ho Guom Turtle (Rafetus swinhoei) is considered holy because of a 15th-century legend describing how King Le Loi drove out invading Chinese with a magical sword, which the gods gave him and which he later returned by giving it to the lake's turtle, which swam it back to the gods. Hoan Kiem Lake is an oasis in urban Hanoi that attracts tourists and locals alike, and the place to go to catch a glimpse of the 300-kilogram Ho Guom Turtle, it’s most famous resident (there is a population of these turtles in the lake, not just one individual). Today (December 21, 2010), m&cnews.com is reporting that Vietnamese scientists are urging Hanoi authorities to wipe out the invasive Red-eared Slider (Trachemys scripta) which is believed to be a threat to Hoan Kiem Lake's legendary chelonian. Professor Ha Dinh Duc, an expert on the giant softshell Rafetus swinhoei, said 'Hanoi's authorities need to make a plan to kill these invaders because if there are no timely and proper measures, red-eared turtles would eat all foods of our native turtle...They even eat all plants in the lake, and the lake would not be green anymore."

Many Hanoians release the North American Red-eared Slider into Hoan Kiem for good luck at holidays, such as the Tet New Year. Thus, they have created the situation, said Pham Dinh Quyen, general secretary of the Vietnam Association for Conservation of Nature and Environment. Red-eared Sliders are now doing well in the lake.

Rafetus swinhoei is probably the world’s largest and rarest softshell turtle species (Family Trionychidae). There are few recent records of them, and what we known about them suggest they have a discontinuous and relictual distribution. The species is known from Tai Hu Lake and the Suzhou area, west of Shanghai, the Red River drainage in Yunnan, in southern China, and from the same river system in northern Vietnam. Rafetus swinhoei have also been reported from Thanh Hoa Province, Vietnam and this is the most southern reported locality for the species, if its presence can be documented. Rafetus swinhoei was already rare in the 1870’s, when Pierre-Marie Heude collected some specimens from the Tai Hu Lake area. In 2009 there were only four captive specimens in China and one in Vietnam, although fishermen’s accounts indicate that some wild animals existed as recently as 10-20 years ago (Le and Pritchard, 2009). Search for museum specimens was conducted by Peter Pritchard, who located about 20 specimens, most of them decades old, and nearly all had been misidentified as species of Pelochelys. Taxonomic confusion started when Heude (1880) ignored John Gray’s description of Oscaria swinhoei (Gray, 1873) and named five species within the genus Yuen to a group of swinhoei specimens from the eastern population. This was not sorted out until 1998 when Meylan and Webb (1998) carefully examined Gray’s type specimen in the British Museum of Natural History and confirmed the validity Rafetus swinhoei. To add to the confusion, Ha Dinh Duc (2000) described Rafetus leloii, based on specimens collected from Hoan Kiem Lake in downtown Hanoi, but Farkas and Webb (2003) placed leloii into the synonymy of swinhoei.

Rafetus swinhoei appears to be on the brink of extinction. Unless immediate action is taken to increase its populations it seems probable that it won't last the century.

Literature


Farkas, B. L. and R. G. Webb, 2003. Rafetus leloii Ha Dinh Duc, 2000 – an invalid species of softshell turtle from Hoan Kiem Lake, Hanoi, Vietnam (Reptilia, Testudines, Trionychidae). Zoologische Abhandlungen 53: 107-112.

Gray, J. E. 1873. Notes on Chinese mud-tortoises (Trionychidae), with the description of a new species sent to the British Museum by Mr. Swinhoe, and observations on the male organ of this family. Ann. Mag. Nat. Hist. 12:156-161.

Ha, D. D. 2000. A new species of the genus Rafetus (Family: Trionychidae) from Hoan Kiem Lake of Vietnam. Archeology Magazine 4:104.



Meylan, P. A . and R. G. Webb, 1988. Rafetus swinhoei (Gray) 1873, a valid species of living soft-shelled turtle (family Trionychidae) from China. Journal of Herpetology 22:118-119.

A New Gastropod-eating Snake


Sazima’s Gastropod-eating Snake, Dipsas sazimai.
Photo credit. João L. Gasparini
 The Neotropical snake genus Dipsas (Family Dipsididae) contains about 35 known species with exceptionally gracile bodies and large heads. The majority of species with known diets feed on gastropods, slugs and snails. The snakes hunt for their soft bodied prey on the ground and in shrubs and trees, and their light weight bodies make it possible for the snakes to use exceptionally slender branches to support their weight. Daniel Fernandes and colleagues have now described Dipsas sazimai from the Atlantic Forest of Brazil. A species in the Dipsas incerta Group that is distinguished from all congeners a combination of patterns and scale counts.  The species is named in honor of Ivan Sazima for his contributions to Brazilian herpetology. Dispas sazimai  inhabits Brazil’s Atlantic Forest from the  state of Alagoas to north of São Paulo from sea level to about 700 m. Sazima’s Dipsas inhabits dense umbrophilous forests and the sample the authors had suggest it is the rarest species of Dipsas in the Atlantic Forest.

Citation
Fernandes, D. S., O. A. V. Marques, and A. J. S. Argolo. 2010. A new species of Dipsas Laurenti from the Atlantic Forest of Brazil (Serpentes: Dipsadidae). Zootaxa 2691:57-66.

Monday, December 20, 2010

Snake on a Rope

Boa constrictor climbing up a rope.
How does a snake climb a vertical
surface without slipping?
(Credit: Bruce C. Jayne)
In a unique study involving young boa constrictors, University of Cincinnati researchers put snakes to work on varying diameters and flexibility of vertical rope to examine how they might move around on branches and vines to gather food and escape enemies in their natural habitat.

The findings by Greg Byrnes, a University of Cincinnati postdoctoral fellow in the department of biological sciences, and Bruce C. Jayne, a UC professor of biology, are published in the December issue of The Journal of Experimental Biology.

The UC researchers sent the snakes climbing up varying widths and tensions of ropes as they explored snake movement in relation to their musculoskeletal design and variation in their environment.

They found that regardless of diameter or flexibility of the rope, the snakes alternated curving between left and right as they climbed the ropes. On the thicker ropes, they were able to move greater portions of their bodies forward as they climbed. As the ropes became thinner and more flimsy, the snakes used more of their bodies -- including their back, sides and belly -- to manipulate the rope for climbing. On larger diameter ropes, snakes applied opposing forces at the same location to grip the rope. While on smaller diameter ropes forces were applied in opposite directions at different locations along the rope, resulting in increased rope deformation. Although energy is likely to be lost during deformation, snakes might use increased surface deformation as a strategy to enhance their ability to grip.

"Despite the likely physical and energetic challenges, the benefits of the ability to move on narrow and compliant substrates might have large ecological implications for animals," write the authors. "Arboreal organisms must often feed or hunt in the terminal branch niche, which requires the ability to move safely on narrow and compliant substrates."

Jayne points out that although the large muscles of boa constrictors make them fairly stocky and heavy compared to other snakes, this anatomy probably increases their strength. All of the snakes gripped the ropes using a concertina mode of locomotion, which is defined by some regions of the body periodically stopping while other regions of the body extend forward. "It turns out boa constrictors are strong enough so that they can support their weight with a modest number of gripping regions," adds Jayne.

The researchers say their findings are the first study that has explicitly examined the combined effects of diameter and compliance on how an animal gets around. Future research is underway to compare differing muscular anatomies in snakes and relate it to their function in terms of their behavior and their environment.

Citation
Byrnes, G. and  B. C. Jayne. Substrate diameter and compliance affect the gripping strategies and locomotor mode of climbing boa constrictors. Journal of Experimental Biology, 2010; 213 (24): 4249 DOI: 10.1242/jeb.047225

Sunday, December 19, 2010

Sex Determination in Gekkota


The Leopard Gecko, Eublepharis maculatus, is
one of the best studied geckos in terms of its
sex-determination mechanism. JCM
The known number of sex determining mechanisms and variations on them seem to be ever increasing in reptiles as we learn more about them. There are species with male and female heterogamety - sex chromosomes; species with temperature-dependent sex determination, and species with both systems. Within each of these there seems to be many variations. Geckos (Gekkota) are the second most specious lineage of lizards (skinks are the first) with more than 1300 species placed in six different families. The diversity of geckos and their sex determination mechanisms make them excellent candidates for studying the evolution of these mechanisms and current knowledge suggests that geckos have transitioned from one mechanism to another many times during their evolutionary history. Yet, of the 1300 species, relatively few (about 46) have been examined for the mechanisms they use. Tony Gamble of the University of Minnesota has recently summarized the sex determination mechanisms used by geckos in various lineages and discovered that at least 8 or 9 transitions have occurred within the last 150 million years, despite the low number of species that have been examined to date. The Carphodactylidae has not been studies at in this regard, and the Diplodactylidae, Phyllodactylidae, and Sphaerodactylidae are poorly known in terms of how they determination the sex of their offspring. Gamble’s work suggests the ancestral gecko used male heterogamety as the determining mechanism with temperature-dependent sex determination evolving 5 times independently from a genetic sex determination ancestor.

Citation