Saturday, April 16, 2011

A Snake Bite & the Use of Snake Repellents

A story carried on, in San Antonio reports a 12-year old boy is in stable condition after being bitten late in the baseball field's dugout by a rattlesnake.The bite occurred in Helotes, Texas a town northwest of San Antonio. The league canceled Thursday and Friday’s games after pest control experts sprayed the ball fields with snake repellent, because of concern that the repellent would "agitate" the snakes. 

The story raises the question - are snake repellents effective? Goggle "snake repellents" and you will find a surprising number of available products claiming to prevent snakes from entering your yard, livestock areas, or campground.

A look at the ingredients in snake repellents reveal a wide range of molecules and compounds that are volitile and have strong odors and includes the following: garlic oil, putrescent egg solids, menthol, menthene, camphor, camphene, carvacrol, thymol, carvone or 1,8-cineol; sulfur, cinnamon oil, clove oil, naphthalene, ammonium carbonate, dieldrin, heptachlor, texaphene, petroleum jelly, benzoyl chloride, civit musk, anise oil, cedarwood oil, clary sage oil, giner oil, grapefruit oil, juniper berry oil, lavender oil, rosemary oil, wintergreen oil yucca oil. The list could be much longer. In fact there seems to be little or no evidence that any of the snake repellents are effective. In fact they may be better at repelling humans, than snakes. See the references below. So, if you are looking to repel snakes, you might as well try the old horse hair rope around the tent trick. At least when it fails you still have the rope.

Some Snake Repellent Research Articles
Ferraro, D. M. 1995. The efficacy of naphthalene and sulfur repellents to cause avoidance behavior in the Plaind Garter Snkae. Great Plains Wildlife Damage Control Worksphop Proceedings. 1995:116-120.

Moran, S., Vaisman, S., Tayar, E. 2008. The efficacy of a naphthalene and sulfur formula to repel the venomous snake Vipera palaestinae in Israel. Applied Herpetology 5:225-232.

San Julian, G. J. 1985. What you wanted to know about all you ever heard concerning snake repellents. Second Eastern Wildlife Damage Control Conference 1985:243-248.

Friday, April 15, 2011

Roger Repp's Suzio Report, March, Part 1

Buenos Howdy Herpers,
Several of you have checked in to ask the "what up" of the reports lately. Truth be told, I've been so overwhelmed with what we're finding that I can't begin to report it all. It has been a glorious winter/spring.
The real story is the Gila Monsters. To date, I have seen 18 different Gilas thus far this year. To put that in perspective, last year was also a very good year, and I only racked up 16. I have yet to do a head count on the atrox, but I expect that I'm also kicking a$ with these.

The best day of the year thus far was 3 March. Jeff Smith and I started the day out with plans to go to sweet spots, but we got distracted, and found even better sweet spots. When the day was over, we observed 6 Gila Monsters, 5 of which were new.
I have NEVER seen five new Gila Monsters in day! 3 is the best I've done, albeit several times. We also observed 17 atrox, a lyresnake, two chuckwallas, a tortoise and a glossy snake that Jeff flipped a piece of tin sheet to find. 
Meanwhile, back at the ranch, in 2001 The Peach and I began the Schuett/Repp Suizo Mountain study with a den we call Atrox Den #1 (AD1). Through the years, the den died out--which I'm seeing is more than a relic of hands-on herping. Dens that I've never touched have died out before my eyes, only to spring back to life a couple years later. 
I think it's all a matter of having a female in the hole. Build a den with a girl in it, and the boys will come (literally and figuratively). 
To make a long story short, AD1 is coming back. 
For now, we'll throw a few pics out, and put together another report in a week or so. 
Pic 1: Spectacular in its remoteness, Gila Knob is a new place that Jeff, Melissa Amarello and I are watching.
Pic 2: The glossy snake that Jeff found on 3 March Photo by Jeff Smith
Pic 3: A new atrox den containing five atrox was found on 3 March. Three of the five can be seen in this photo. Unbeknownst to me at the time, there were two MONSTER tortoises in the hole behind these guys.
Pic 4: The same den 3 days later. Photo by Jeff Smith
Pic 5: A young atrox viewed at a den site on 3 March. It is rare to see youngsters occupying a denning situation.
Pic 6: A rerun. In the crevice just downslope from pic 5, a Gila and another young atrox were observed haniging out together. Jeff found both snakes together on his 6 March visit
Pic 7: The den comes back! Picture of a male atrox basking at AD1, 22 March 2010.
Pic 8: Obviously the same male viewed as last picture, 13 March 2011. On 12 March, John Murphy and I saw three males out here--the first time I've seen multiple snakes here since 2006. Welcome back AD1!
Pic 9: Another den to suddenly spring back to life on our little hill is AD8. On 2 April, Dale Denardo and I, along with others, found five atrox. The next day, Natalie Rowe, Gordon Campbell and I found this pair hooked up there.
With the next report, we'll show some more of these Gilas I'm talking about, as well as some drop dead gorgeous tortoise images.
This is not all that is fit to spit, but it will have to do for now.
Best to all, roger

Nocturnal Behavior Correlated With Orbit Morphology in Dinosaurs

The movie "Jurassic Park" got one thing right: Those velociraptors hunted by night while the big plant-eaters browsed around the clock, according to a new study of the eyes of fossil animals. The study was published online today (April 14) in the journal Science.

This conclusion overturns the conventional wisdom that dinosaurs were active by day while early mammals scurried around at night, said Ryosuke Motani, professor of geology at UC Davis and co-author of the paper.

Scleral Ring of a Gecko. JCM
"It was a surprise, but it makes sense," Motani said.

The research is also providing insight into how ecology influences the evolution of animal shape and form over tens of millions of years, according to Motani and collaborator Lars Schmitz, a postdoctoral researcher in the Department of Evolution and Ecology at UC Davis.

Motani and Schmitz, a former graduate student of Motani’s, worked out the dinosaur's daily habits by studying their eyes.

Dinosaurs, lizards and birds all have a bony ring called the "scleral ring” in their eye, a structure that is lacking in mammals and crocodiles. Schmitz and Motani measured the inner and outer dimensions of this ring, plus the size of the eye socket, in 33 fossils of dinosaurs, ancestral birds and pterosaurs. They took the same measurements in 164 living species.

Day-active, or diurnal, animals have a small opening in the middle of the ring. In nocturnal animals, the opening is much larger. Cathemeral animals -- active both day and night -- tend to be in between.

The size of these features is affected by a species’ environment (ecology) as well as by ancestry (phylogeny). For example, two closely related animals might have a similar eye shape even though one is active by day and the other by night: The shape of the eye is constrained by ancestry.

Schmitz and Motani wrote a computer program to separate the "ecological signal" from the "phylogenetic signal." The results of that analysis are in a separate paper published simultaneously in the journal Evolution.

By looking at 164 living species, the UC Davis team was able to confirm that eye measurements are quite accurate in predicting whether animals are active by day, by night or around the clock.

They then applied the technique to fossils from plant-eating and carnivorous dinosaurs, flying reptiles called pterosaurs, and ancestral birds.

The measurements revealed that the big plant-eating dinosaurs were active day and night, probably because they had to eat most of the time, except for the hottest hours of the day when they needed to avoid overheating. Modern megaherbivores like elephants show the same activity pattern, Motani said.

Velociraptors and other small carnivores were night hunters, Schmitz and Motani showed. They were not able to study big carnivores such as Tyrannosaurus rex, because there are no fossils with sufficiently well-preserved scleral rings.

Flying creatures, including early birds and pterosaurs, were mostly day-active, although some of the pterosaurs -- including a filter-feeding animal that probably lived rather like a duck, and a fish-eating pterosaur -- were apparently night-active.

The ability to separate out the effects of ancestry gives researchers a new tool to understand how animals lived in their environment and how changes in the environment influenced their evolution over millions of years, Motani said.

The work was funded by the National Science Foundation and a postdoctoral fellowship from the Deutsche Forschungsgemeinschaft (Germany) to Schmitz.

Lars Schmitz and Ryosuke Motani. Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology. Science, 14 April 2011 DOI: 10.1126/science.1200043

Thursday, April 14, 2011

From the Brains of Toads

Bombina maxima
Frog and toad skins already are well known for the of hundreds of germ-fighting substances. Now a new report in the American Chemical Society's Journal of Proteome Research reveals that the toad brains also contain an abundance of antibacterial and ant-iviral substances that could inspire a new generation of medicines.

Despite many studies showing that amphibians synthesize and secrete a remarkably diverse array of antimicrobial substances in their skin, little is known about the molecules produced in their brains. Rui Liu and colleagues decided to begin filling that knowledge gap by analyzing brains from the Giant Fire-Bellied Toad (Bombina maxima), and the Small-webbed Bell Toad (Bombina microdeladigitora). They discovered 79 different antimicrobial peptides, the components of proteins, including 59 that were totally new to science. The diversity of the peptides "is, to our knowledge, the most extreme yet described for any animal brains," they noted. Some of the peptides showed strong antimicrobial activity, crippling or killing strains of staph bacteria, E. coli, and the fungus that causes yeast infections in humans. These promising findings suggest that the toad brains might be a valuable source for developing new antibacterial and antiviral drugs. The antimicrobial peptides discovered belong to two peptide groups (maximin and maximin-H). Some of the antimicrobial peptides showed strong antimicrobial activities against Gram-positive and -negative bacteria and fungi.

Rui Liu, Huan Liu, Yufang Ma, Jing Wu, Hailong Yang, Huahu Ye, Ren Lai. There are Abundant Antimicrobial Peptides in Brains of Two Kinds of Bombina Toads. Journal of Proteome Research, 2011; 10 (4): 1806 DOI: 10.1021/pr101285n

Wednesday, April 13, 2011

Daemonosaurus chauliodus of Ghost Ranch, New Mexico

This rendering of Daemonosaurus
chauliodus shows its size relative to an
 American quarter. The species name 
chauliodus is derived from the Greek 
word for “buck-toothed” and refers to 
the species’ big slanted front teeth.
Artist Credit: Jeffrey Martz

A team of scientists led by the Smithsonian Institution has discovered a fossilized dinosaur skull and neck vertebrae that not only reveal a new species, but also an evolutionary link between two groups of dinosaurs. The new species, Daemonosaurus chauliodus, was discovered at Ghost Ranch, N.M. The team's findings are published in the Proceedings of the Royal Society B, Wednesday, April 13.

The oldest known dinosaurs walked or ran on their hind legs and included early predatory species such as Herrerasaurus. They existed in what are now Argentina and Brazil early in the Late Triassic Period, approximately 230 million years ago. The evolutionary position of these early predatory dinosaurs was contentious because there was a gap in the fossil record between them and later theropod dinosaurs. The team's discovery of Daemonosaurus chauliodus helps fill in this gap.

Because only the skull and neck of Daemonosaurus were found, the total length of the new species is unknown. The dinosaur's skull, however, is narrow and relatively deep, measuring 5.5 inches long from the tip of its snout to the back of the skull and has proportionately large eye sockets. The upper jaw has large, forward-slanted front teeth. It is this feature that helped the scientists name the species. The name Daemonosaurus is based on the Greek words "daimon" meaning evil spirit (because it was found at Ghost Ranch), and "sauros" meaning lizard or reptile. The species name chauliodus is derived from the Greek word for "buck-toothed" and refers to the species' big slanted front teeth.

Daemonosaurus, a basal (primitive) theropod species, was dated to the latest part of the Triassic Period approximately 205 million years ago, just before the beginning of the Jurassic Period. This altered the previous belief that all basal dinosaurs had vanished millions of years earlier. The skull and neck vertebrae of Daemonosaurus also revealed several features similar to those in neotheropods—the succeeding group of dinosaurs on the evolutionary timeline.

"Various features of the skull and neck in Daemonosaurus indicate that it was intermediate between the earliest known predatory dinosaurs from South America and more advanced theropod dinosaurs," said Hans Sues, curator of vertebrate paleontology at the Smithsonian's National Museum of Natural History and lead author of the team's findings. "One such feature is the presence of cavities on some of the neck vertebrae related to the structure of the respiratory system."

This new discovery shows that there is still much to be learned about the early evolution of dinosaurs. "The continued exploration of even well-studied regions like the American Southwest will still yield remarkable new fossil finds," Sues said.

Hans-Dieter Sues, Sterling J. Nesbitt, David S Berman, and Amy C. Henrici.  A late-surviving basal theropod dinosaur from the latest Triassic of North America. Proceedings of the Royal Society B published online before print April 13, 2011,doi:10.1098/rspb.2011.0410

Sunday, April 10, 2011

Scutulatus from Cochise County, AZ

The Mojave Rattlesnake, Crotalus scutulatus. JCM
Mojave rattlesnakes (Crotalus scutulatus) in Arizona have two quite different kinds of venom. The venom of population A (venom A) contains the toxin known as ‘Mojave toxin’ and it lacks hemorrhagic and specific proteolytic activities- instead it acts on the nervous system. Population B (venom B) does not contain Mojave toxin but instead produces hemorrhagic and proteolytic activities, acting on blood and blood vessels. This situation has been known since at least 1988. Glenn and Straight (1988) examined the venom of 15 Crotalus scutulatus scutulatus from the regions between the venom A and venom B populations in Arizona for the presence of Mojave toxin Seven of the venoms contained both the Mojave toxin of venom A and the proteolytic and hemorrhagic activities of venom B. The i.p. LD50 values of the A+B venoms were 0.4–2.6 mg/kg, compared to 0.2–0.5 mg/kg for venom A individuals and 2.1–5.3 mg/kg for the venom B individuals.Thus, populations with the A+B venom type are almost twice as venomous (at least to mice) as snakes with venom A or B types. Their results suggested an intergrade zone exists between the two venom types which arcs around the western and southern regions of the venom B population. Within these regions, three major venom types (A, B and A+B) can occur in Crotalus s. scutulatus. Thus, the reason for the following article. Crotalus scutulatus is most likely the most dangerous North American rattlesnake.

Glenn, JL and Straight, RC. 1988. Intergradation of two different venom populations of the Mojave rattlesnake (Crotalus scutulatus scutulatus) in Arizona. Toxicon 27, 411-418.

Cochise County's rattlesnakes even deadlier than most
Carly Kennedy
Arizona-Sonora News Service

Like humans, rattlesnakes like the outdoors this time of the year.

And the Mojave rattlesnake that's commonly found in Cochise County might be more deadly than any rattler in any other area of Arizona.

Emergency room doctors in Tucson and Sierra Vista have noticed that patients who suffer from a Cochise County Mojave rattlesnake bite do respond well to the anti-venom, but they often come back to the hospital complaining of the same symptoms.

Herpetologists have gathered from these cases that the Mojave rattlesnakes in Cochise County have venom that is more potent than that from Mojaves in other counties, said Brian Gill, owner of the Tombstone Reptile Exhibit.

One of the supporting theories behind this confusing trend has to do with the type of food the Cochise Mojave eats.

Mojaves typically eat rodents, but in Cochise County there aren't as many rodents available, and so the rattlesnakes in the region have grown accustomed to eating snacks that are more accessible, such as lizards and geckos, Gill said.

"This might be converting the toxins in their body into a more potent toxin," he added.

The Mojave rattlers are one of only four snakes in Arizona that have venom that is a neurotoxin. Upon entering the human body, the toxin starts attacking the nervous system and can ultimately lead to cardiac arrest or respiratory arrest.

Even with its powerful venom, the Mojave is not the most common species in the county, said Tombstone animal control officer James Everetts. He said the most prevalent species of rattler is the Western diamondback.

The diamondback rattlesnake has venom that is a hemotoxin, which affects the surrounding tissue of the bitten area. After the bite has occurred, the hemotoxin starts eating away tissue and causes a "burning" sensation, said Everetts, who has been bitten three times.

"It's like touching an open flame, but you can feel that pain inside your body," he said.

Rattlesnake season spans throughout early spring well into the summer months, seeing its height in May and June, which is the mating season, Gill said.

Experts warn to avoid the snakes altogether, especially during their midday sunning on nearby rocks. "As the snake's energy level increases, so does its aggression," Gill said.

At night, the snakes migrate to roadways because the asphalt acts as a source of warmth. Nighttime serves as their hunting time, so they can be aggressive and should be avoided, Gill said.

During snake season Tombstone Animal Control receives plenty of calls, but those tend to come in spurts as the rattlesnakes migrate in search of food and water. During runs of hotter weather, there will be an average of two calls a week, Everetts said.

"They spread out everywhere to find food and water, so I can go weeks without hearing of any sightings," he added.  Everetts warned victims of a diamondback strike not to place ice or heat on the infected area.

"Ice will keep the hemotoxin centralized, and it will eat away at the surrounding tissue," he said. "And heat will spread the poison too quickly." The best thing a rattlesnake bite victim can do immediately is wash the area with antibacterial soap, circle the marks the snake has made and write down the approximate time of the bite, Everetts said.

"When you get to the hospital, this allows the physicians to judge the severity of the swelling and how fast the poison is moving through the system."

Saturday, April 9, 2011

Invasive Herps & Brain Size

Why is it that some amphibian and reptile species become invasive, while others do not? The anwer to this question may rest in the relative brain size of the species. This question is addressed in a new article by Joshua J. Amiel, Reid Tingley, and Richard Shine of the University of Syndney.  They report that amphibians and reptiles have smaller forebrains than birds and mammals, and are often viewed to have less behavioural complexity. In an effort to examine the relationship between larger brain size and capacity to thrive in a novel environment, the authors analysed data on human introductions of amphibians and reptiles to areas outside of their native geographic ranges. They assumed that if a larger brain facilitates dealing with new challenges, success in establishing feral populations following a human introduction will be higher in amphibians and reptiles with large brains relative to their body sizes.

They found brain size relative to body size was, in fact, larger in species of amphibians and reptiles reported to be successful invaders, compared to species that failed to thrive after translocation to new sites.
This was the same evolutionary trend previously found in birds and mammals suggesting that larger brain size enhances the ability to deal with novel environmental challenges in all major clades of terrestrial vertebrates. Interestingly, this pattern was present in all biogeographic regions, except Australasia. Introduced amphibians and reptiles with smaller (rather than larger) brains were more successful at establishing populations in Australasia. This may result from environmental factors selecting against larger brain size where a lack of resources exacerbates the energetic costs of maintaining such an energy expensive organ. The authors prpose that low resource availability in Australasia may favour small brain size and other traits that reduce an animal's total energy requirements. They note evolutionary trends towards reduced fecundity levels in rodents and in birds that have invaded Australia over longer time periods reinforce this hypothesis.

Amiel JJ, Tingley R, Shine R (2011) Smart Moves: Effects of Relative Brain Size on Establishment Success of Invasive Amphibians and Reptiles. PLoS ONE 6(4): e18277. doi:10.1371/journal.pone.0018277

Friday, April 8, 2011

The Decline of the Adder in the United Kingdom

Recent reports from the UK suggest that the only venomous snake found on the island nation is in serious trouble. Herpetologists from Natural England, Zoological Society of London (ZSL) and Oxford University have teamed up examine the status of  the  Adder. In the last decade it has declined, and surveys suggest a third of remaining adder populations may comprise fewer than ten adults, and likely results from degradation and fragmentation of habitat. Small populations, particularly in the English Midlands, are not capable of maintaining a healthy level of genetic diversity, which makes them less resilient to disease, and make them more susceptible to enetic defects, which in turn could lead to local extinctions. Dr Trent Garner, Senior Research Fellow at ZSL’s Institute of Zoology is quoted as saying, “Genetic diversity has been shown to be a key component for successful adder populations in Sweden and Hungary, but has yet to be studied in the UK. Our goal is to provide the first insights into how population size and isolation may be related to genetic diversity of the UK’s adders.” Jim Foster, herpetologist for Natural England, said, “With around a third of adder populations now restricted to isolated pockets of habitat, and with only a handful of snakes per site, they could be especially vulnerable. As we have seen with natterjack toads, populations that are small and isolated can start to decline purely through genetic effects. This ground-breaking study will see if adders are suffering a similar plight....Fortunately, if there are problems we still have time to deploy a number of conservation remedies. Habitat restoration and the creation of wildlife corridors will help get these snakes back on the move. We may even consider moving adders between populations, to artificially promote “gene flow” - although that carries risks and we’d need to look more closely at the genetics results before proceeding.” [Photo: The Adder, Vipera berus. Photo Credit: Marek Szczepanek].

Tobias Uller of Oxford University’s Department of Zoology agreed, saying, “When populations become small and isolated, with it comes the risk of expression of harmful genetic variants that normally remain ‘hidden’ in larger populations. Loss of genetic variation may also compromise the population’s ability to evolve – a problem that is particularly acute when habitats change rapidly or if a new disease emerges.”

The Adder is one of four reptiles  species described as "widespread" because they are scattered over a large area in Britain. It can be found from the south-west England all the way north to Scotland. But this not dose not mean the species is abundant, within their large distribution, they are restricted to grassland, scrub and woodland edge, primarily on sandy soils.

In 2004, English Nature (now Natural England) surveyed naturalists around the country asking them to evaluate the health of Vipera berus populations, the results suggested "disturbance" was the greatest threat. A third of the populations were small (estimated as fewer than 10 adult snakes), and a third of the populations were isolated. Population declines and extinctions tended to be more frequent in small and isolated populations.

Make the Adder Count, is a project encouraging local Adder conservation and long-term monitoring of populations, information from a small but dedicated band of Adder-watchers around the countrymay be able to alert conservationists of populations in trouble. Disturbance can have different causes. In some cases it is destruction of habitat, but the snakes are still being killed by humans. And, disturbance can also result from people visiting well-known adder sites.
Baker, J. 2011. Why we must make the adder count., April, 3, 2011.

Georgia Wildlife Officials Criticized for Rattlesnake Roundup Permit

ATLANTA— The Center for Biological Diversity and allies today sent a letter to the Georgia Department of Natural Resources denouncing a state wildlife exhibition permit issued for the Claxton Rattlesnake Roundup held on March 12 in Evans County. In January the groups sent a letter to the agency pointing out that state law requires a permit to display wildlife in public. The law states that the permit can only be issued if the display is solely for educational purposes. The Wildlife Resources Division issued the permit anyway, even though the display of rattlesnakes at the controversial roundups is not solely for educational purposes. Today’s letter urges state wildlife officials not to issue permits for roundups in the future.

“Roundups, which persecute and exploit Georgia’s wildlife, are obviously not solely for educational purposes,” said Tierra Curry, a biologist at the Center, which has opposed rattlesnake roundups in part because they harm eastern diamondback rattlesnakes, a once-common species in the Southeast that in recent years has seen its populations decline.

“Rattlesnake roundups” are annual contests where hunters bring in as many snakes as they can catch in a year to be milked for venom, butchered, then sold for meat and skin. Two roundups take place every year in Georgia, one in Whigham in January, the other in Claxton in March. The letter was sent by the Center, One More Generation, the Coastal Plains Institute and Land Conservancy, and Protecting All Living Species.

“The Department of Natural Resources is charged with protecting Georgia’s resources for future generations, not with endorsing the unlimited hunting of one of our state’s rare species,” said Jim Ries, community director at One More Generation, which was founded by two elementary students in Georgia.

“The Georgia legislature never intended for this law to be used to justify the removal of animals from the wild for entertainment purposes. By issuing this permit the agency is contributing to the impending destruction of this species,” said Bill Matturro, founder of Protecting All Living Species, based in south Georgia.

A recently published study shows that rattlesnake roundups have depleted populations of eastern diamondback rattlesnakes in the southeastern United States. This once-common species is being pushed toward extinction by hunting pressure, habitat loss and road mortality. The snake hasn’t been seen in Louisiana since 1980, and is now uncommon throughout its range in Alabama, Florida, Georgia, Mississippi and the Carolinas. In response to dwindling rattlesnake populations, public pressure and environmental concerns, the town of Fitzgerald, Ga., replaced its rattlesnake roundup with a wild chicken festival, which organizers report has been an enormous success.

“All rattlesnake roundups should be replaced with festivals celebrating wildlife and offering educational programs on the importance of saving native species,” said Dr. Bruce Means, author of the recent study and executive director of the Coastal Plains Institute and Land Conservancy.

Thursday, April 7, 2011

Evidence of the Benefits of Biodiversity

The following is a press release from NFS - April 6, 2011
View a webcast with Bradley Cardinale of the University of Michigan.

Frequent reports of accelerating species losses invariably raise questions about why such losses matter and why we should work to conserve biodiversity.

Biologists have traditionally responded to such questions by citing societal benefits that are often presumed to be offered by biodiversity--benefits like controlling pests and diseases, promoting the productivity of fisheries, and helping to purify air and water, among many others. Nevertheless, many of these presumed benefits are have yet to be supported by rigorous scientific data.

But Bradley J. Cardinale of the University of Michigan has produced a new study that finally verifies that biodiversity promotes water quality and explains how it does so. Specifically, the study reveals how biodiversity helps remove excess levels of nutrients from streams that commonly degrade water quality.

Cardinale said, "This is the first study that nails the mechanism by which biodiversity promotes water quality. And by nailing the mechanism, it provides solid evidence of a cause-and-effect relationship between biodiversity and water quality that was previously missing."

Here's how Cardinale's mechanism works: as the number of species of algae in a stream increases, the geographical distribution of these organisms within the stream expands, and the more water these widely distributed organisms may cleanse through a pollution-removing process common to algae.

Cardinale's study, which appears in the April 7 issue of Nature, was funded by the National Science Foundation.

The cleansing power of biodiversity
Scientists have long known that ecosystems that have more plant species tend to have a greater capacity to remove pollutants from soil and water than do ecosystems that have fewer species. But, until now, no one knew how or why this is so.

Cardinale's study helps solve this mystery by explaining how biodiversity promotes the self-cleaning power of streams. According to the study, as algae grow in streams and produce more biomass, they incorporate into their bodies some common forms of pollution and thereby remove it from the water. Each species of pollution-removing algae has evolved and adapted to a different set of conditions, and so occupies a unique mini habitat, or niche, within a water body. Therefore, as the number of species of pollution-removing algae increases in a stream, so too does the number of unique niches that are occupied, filtered and cleansed by them. Hence: the more algae species a stream has, the more total pollutants these organisms may remove from the water.

"As the different habitats in a stream are filled by diverse populations of algae, the stream receives more total biofiltration," said Cardinale. "It's as if the algae work as a better sponge."

"Algae are the sort of thing that are easily overlooked, however Cardinale provides an elegant experiment that shows how the biological diversity of algal species greatly increases the removal of one of the most deadly and insidious toxins in our streams, lakes and rivers," said George W. Gilchrist, a program director in NSF's Division of Environmental Biology.

The process by which species evolve to inhabit their own, unique habitats is known as niche partitioning. "People as far back as Darwin have argued that species should have unique niches, and as a result, we should see a division of labor in the environment," Cardinale said. "But demonstrating that directly has proven very difficult."

The varied types of habitats that may exist within any particular stream include, for example, areas where water flows swiftly vs. areas where water flows slowly.

Study design
Cardinale began his study by growing from one to eight species of algae that are common to North America in each of 150 miniature model streams; each model stream was designed to mimic the varied flow conditions that exist in natural streams, including those dominated by riffles, runs, or calm pools. He then measured the ability of each algal community to soak up a nitrogen compound called nitrate. Cardinale chose nitrates to represent pollution in the study because excess nitrogen is the most common pollutant and the leading cause of degraded water quality worldwide.

Nitrogen is a nutrient found in all living organisms. But excess nitrogen is a pollutant that is usually carried to water bodies in runoff containing nitrogen-based fertilizers and nitrogen-bearing sewage.

Various species of algae were chosen to represent biodiversity in the study because algae are the primary organisms that take up excess nutrients, such as nitrogen, from streams, lakes and oceans.

The power of niche partitioning
Cardinale's results showed that nitrate uptake in the model streams increased linearly with species diversity. On average, the eight-species mix removed nitrate 4.5 times faster than did a single species grown alone.

Evidence that these results were produced by niche partitioning includes the domination of differently shaped forms of algae in different types of stream habitats, as predicted by ecological theory. For example, high velocity habitats were dominated by small, single-celled species of algae that grew in ways that were resistant to displacement by the force of fast-moving water. By contrast, low velocity habitats were dominated by large, filamentous algae that were vulnerable to such forces.

In addition, as part of the research, streams were experimentally simplified until they contained just one type of a habitat, and no opportunity for species to express their niches. Results showed that each of these simplified water bodies then collapsed to one dominant species that singularly drove all nitrate uptake, without species diversity influencing such uptake. These result confirmed that niche differences among species provided the mechanism for biodiversity's cleansing ability.

"One of the primary contributions of this study," said Cardinale, "is that I was able to show exactly why streams that have more species are better at removing these nutrient pollutants from the water. It's just one study, but it's part of a growing body of scientific evidence that is now clearly showing that the modern mass extinction of species is going to affect humanity in some big, and important ways."

Implications of study
Cardinale continues, "One of the obvious implications of the study is that if we want to enhance water quality in large bodies of water, like the Chesapeake Bay watershed or around the Great Lakes, then the conservation of natural biodiversity in our streams would offer, among other benefits, help in cleaning them up."

Nevertheless, scientists are currently warning that accelerating species loses may ultimately lead to a mass extinction comparable in magnitude to that which wiped out the dinosaurs--a possibility that certainly threatens the biodiversity of rivers, streams and other water bodies.

Wednesday, April 6, 2011

Bufo viridis on the Iberian Peninsula

The green toad (Bufo viridis) was present 

in the Iberian Peninsula during the late 
Analysis of fossils found in the Cueva Victoria deposit in Cartagena (Murcia), has for the first time confirmed the presence of the green toad (Bufo viridis) in south eastern Spain at the end of the Early Pleistocene (more than 1.1 million years ago), in the provinces of Granada, Murcia and Castellón.

"Around 500 fossilised bones document the entire skeleton of the green toad, and provide key osteological clues that mean they can be unequivocally attributed to this species," says Hugues-Alexandre Blain, one of the authors of the study and a researcher in the Prehistory Department at the Rovira i Virgili University (URV) in Tarragona.

The study, which has been published in Comptes Rendus Palevol, shows that at this time the amphibian belonged to a different subspecies than the green toads of today. Changes in the climate and landscape, "which have taken place frequently over the past two million years," could be the reason for them having become locally extinct.

Nowadays, B. viridis is distributed extensively throughout Eurasia and northern Africa, but until now its presence had never been demonstrated in the Iberian Peninsula. "Although the peninsula has favourable ecological conditions, the species is strangely absent," the expert says.

The south western limit of its current range in Europe is the border between Italy and France. In Spain, it is only found in the Balearic Islands, "where it is thought to have arrived recently, possibly having been introduced by the Phoenicians from northern Africa," says Blain.

Why did it disappear in the Iberian Peninsula?
There are various theories as to the causes that led to the green toad disappearing from the Peninsula during the Pleistocene. "Growing climate changes and in particular the cold period seen around one million years ago could be possible explanations," the scientist explains.

However, pressure from the natterjack toad (Bufo calamita), "which is stronger and more competitive," may have displaced the green toad and "made it locally extinct," leaving it "trapped" in south eastern Spain. The expert says that "we will only be able to find out what really caused the local extinction of B. viridis by carrying out studies on more deposits, covering a more extensive geographical area and longer time period."

In search of its ancestor
The green toad belongs to the family Bufonidae, but its ancestor is unknown. "Molecular studies suggest that green toads had an ancestor in Central Asia, but the oldest fossil record found to date is from the Early Miocene (more than 20 million years ago) in France and Spain," explains Blain.

In Spain, the closest living toad relative of B. viridis is the Natterjack Toad, which is found all the way to Ukraine. In Europe, "Bufo priscus could be a good candidate for the title of the European ancestor of B. viridis," says the scientist, who believes it is necessary to carry out a "serious review of all the fossils attributed to this group in Europe, Africa and Asia."

Hugues-Alexandre Blain, Luis Gibert, Carles Ferràndez-Cañadell. First report of a green toad (Bufo viridis sensu lato) in the Early Pleistocene of Spain: Palaeobiogeographical and palaeoecological implications. Comptes Rendus Palevol, 2010; 9 (8): 487 DOI: 10.1016/j.crpv.2010.10.002

Tuesday, April 5, 2011

Tadpoles and an Invasive Crustacean

After 30 years, the common frog can not activate their defenses against the American crayfish.

Iván Gómez Mestre and Carmen Díaz Paniagua, biologists from the Biodiversity Research Unit of the Principality of Asturias CSIC-Universidad de Oviedo and Station Biological relevance of Doñana (CSIC) respectively have confronted two groups of tadpoles with the American crayfish and have compared the degree of activation of their defenses. The researchers note that, despite the common frog tadpoles activated when they detect predators, are unable to perceive the American crayfish, which leaves no recourse for this invasive species.

"The common frog in the Doñana National Park has not yet adapted to the American red crayfish (Procambarus clarkii ) [photo]," said Iván Gómez Mestre. Both the common frog tadpoles in the wetlands of Donana, a town three decades has been in contact with this predator (between 10 and 15 generations), and tadpoles from populations that are faced by first time crab responded the same way: "The degree of activation of defenses is the same in both cases: null," says the biologist.

Tadpoles, explains, they have many defenses available to it, but when they detect the chemical signals (the smell dissolved in water) of a predator such as dragonfly larvae can morphological and behavioral changes.
"The changes in shape result in a wider tail and more pigmented, which attracts the predator to her leaving intact the vital organs and no tears or loss of tail have such serious consequences, since they can regenerate. And changes in behavior resulting in a reduction of activity that passed over unnoticed, "said Iván Gómez Mestre.

But these changes, despite improved survival in case of predators, have a price: "By reducing its activity, the tadpoles were fed less, grew more slowly and faced with the progress of your pond dry season, addition to give advantage to competitors for food, "says the researcher. Hence, the activation of defenses is not permanent and depend on the detection of the predator species by the tadpoles.
An evolutionary race

The results published today contribute to better understand the series of changes that occur in the Iberian ecosystems that invasive crab, native to the Southeastern U.S. and present from Doñana to Asturias. As indicated by Iván Gómez Mestre, among other effects "are known to be in areas that present the American crayfish is a proliferation of predatory birds, so that the pressure on amphibians increases even more."
"The question is whether common frog populations exposed to American crayfish have enough time before dying to adapt to the presence of an introduced predator so voracious. Can not venture a period in evolutionary terms, because each species responds differently, but a reference can be detected cases in the U.S. adaptation of bullfrog tadpoles by introduced fish against the man after 110 years of contact, "says researcher.

The species was detected 15 years ago in Asturian rivers. The American crayfish damage native ecosystems and particularly harmful to salmonids, small fish, amphibians, and vegetation waters. It has also displaced the native crayfish ( Austropotamobius pallipes lusitanicus) in almost all waterways.

This situation has led to initiatives such as the Crab Project:

Ivan Gomez-Mestre and Carmen Díaz-Paniagua. (2011)  Invasive predatory crayfish do not trigger inducible defences in tadpoles Proc. R. Soc. B published online 30 March 2011doi:10.1098/rspb.2010.2762

Monday, April 4, 2011

Zhuchengtyrannus magnus - a T. rex Relative

Scientists have identified a new species of gigantic theropod dinosaur, a close relative of T. rex, from fossil skull and jaw bones discovered in China.

According to findings published in the scientific journal Cretaceous Research, the newly named dinosaur species “Zhuchengtyrannus magnus” probably measured about 11 metres long, stood about 4 metres tall, and weighed close to 6 tonnes.

“We named the new genus Zhuchengtyrannus magnus - which means the ‘Tyrant from Zhucheng’ - because the bones were found in the city of Zhucheng, in eastern China's Shandong Province,” says Dr Hone.

A key member of the international team of scientists involved in the study is Professor Xu Xing of the Beijing Institute of Vertebrate Paleontology and Paleoanthropology in China.

Professor Xu has named more than 30 dinosaurs, making him the world leader in describing new dinosaur species.

The tyrannosaurines, the group including T. rex and its closest relatives, were huge carnivores characterised by small arms, two-fingered hands, and large powerful jaws that could have delivered a powerful bone-crushing bite. They were likely both predators and scavengers.

Together with nearby sites, the quarry in Shandong Province, eastern China where the remains of this huge carnivore were found contains one of the largest concentrations of dinosaur bones in the world. Most of the specimens recovered from the quarry belong to a gigantic species of hadrosaur, or duck-billed dinosaur. Research suggests that the area contains so many dinosaur fossils because it was a large flood plain where many dinosaur bodies were washed together during floods and fossilised.

Zhuchengtyrannus magnus was named in honour of Zhucheng, the city in eastern China where the fossils were found. Tyrannus is the Latin for ‘king’ or ‘tyrant’, and magnus is the Latin for ‘great’. The name is intended to convey ‘great tyrant of Zhucheng’. This new dinosaur species, alongside Tarbosaurus and Tyrannosaurus, is one of the largest members of the tyrannosaurines, a specialised group of large theropods that lived during the Late Cretaceous Period (99 to 65 million years ago).

David W.E. Hone, Kebai Wang, Corwin Sullivan, Xijin Zhao, Shuqing Chen, Dunjin Li, Shuan Ji, Qiang Ji, Xing Xu. A new tyrannosaurine theropod, Zhuchengtyrannus magnus is named based on a maxilla and dentary. Cretaceous Research, 2011; DOI: 10.1016/j.cretres.2011.03.005

Sunday, April 3, 2011

Eggs & Tadpoles of the Indian Brown Frog

The Indian Brown Frog, Indirana semipalmata. 
Photo Credit: 
L. Shyamal
A metamorphosing Indirana semipalmata.
 Photo Credit: L. Shyamal
Indirana is a genus of about 11 species endemic to the Western Ghats of southern India that usually breed in the splash zone of streams, the tadpoles are semi-terrestrial, using water that condenses on leaf litter, rocks, soil and other surfaces. They have been placed in the families Ranidae and Ranixalidae. Indirana semipalmata inhabits Tamil Nadu and Kerala in southern India and by all accounts it is relatively common and widespread at elevations between 200 and 1,100 meters above sea level. The adults are terrestrial in the leaf-litter of tropical forests and swamps and it has been recorded in coffee plantations and secondary forest. Ben Tapley of is reporting that in July of 2010 an amphibian ecology study at the Agumbe Rainforest Research Station (ARRS) in Karnataka, India ( found several egg clutches and tadpoles of this frog that were laid on the bark of a tree. Tadpoles from another clutch were observed feeding on the bark of the same tree. Three clutches of  Indirana semipalmata eggs were at least 3 m away from any standing water, and they suggest this is the first recorded case of tadpoles feeding on a bark substrate and subsequently metamorphosing on the bark of a tree. Tapley suggests this may be a localised phenomenon as Agumbe has the second highest annual rainfall in India and therefore these semi terrestrial tadpoles do not desiccate. Living in Agumbe during the monsoon was literally like living in a cloud. However, since these frogs have evolved in this environment, it would seem likely that this is their life style, and it raises the question of exactly what are the tads eating? Are they actually eating the bark or, more likely in my opinion algae, fungi, or other protists growing on the tree's surface? Also, because of the habitat difference - laying eggs on trees, instead of stream side rocks reported for other populations, it suggests this population could be a different species.

Friday, April 1, 2011

Thailand and the Trade in Reptiles & Amphibians

I have always had an eversion to crowds of people so a trip to the Chatuchak Weekend Market in Bangkok is always a challenge. Not only is it shoulder to shoulder with fellow shoppers, if it rains - a common occurence in Bangkok - the entire market floods and then you are shopping in several inches of water. The 35-acre market has more than 8,000 stalls and a typical weekend draws 200,000 people all looking for a bargain.

However, this market is of particular interest because it includes a wide selection of wildlife, given the crowds it is the only reason I would attend more than once. In fact I have visited the market several times and am amazed as to the number of squirrels with collars and leashes pinned to vendor's shirts. Of course there are dogs, cats, birds, and many fish. But their are also many amphibians and reptiles for sale. Some are the typical pet shop species, boa constrictors, corn snakes, and iguanas. But, others have plastic bottles filled with unusual snakes, lizards, and frogs - often located under the counter.  Here its possible to encounter a Cryptelytrops venustus or a Naja sputatrix. But perhaps most surprisingly some of the large, rare softshell turtles of the Mekong drainage, like Chitra and Peltochelys are forsale from aquariums.
Cryptelytrops venustus, not from the market.

This week Vincent Nijman and Chris R. Shepard report on the role of Thailand in the international trade in CITES listed herpetofauna. Using data in the WCMC-CITES trade database, they establish that a total of 75,594 individuals of 169 species of reptiles and amphibians (including 27 globally threatened species) were imported into Thailand between 1990 and 2007. They found the majority of individuals (59,895, 79%) were listed as captive-bred and a smaller number (15,699, 21%) as wild-caught. Small numbers of individuals of a few species were imported into Thailand in the 1990's, but in 2003 both volume and species diversity increased rapidly. Wild-caught individuals were mainly sourced from African countries, and captive-bred individuals from Asian countries (including from non-CITES Parties). They found  significant discrepancies between exports and imports. While, Thailand reports importing less than 10,000 individuals (51 species) originating from Kazakhstan, Kazakhstan reports no exports of these species. Similar discrepancies, involving smaller numbers were found with other countries.
The Mekong Narrow Headed 
Softshell Turtle, Chitra chitra. Rescued
from the market.
They consider the international wildlife trade as one of the leading threats to conserving biodiversity. And, while it is a probelm - let's think about the larger problem - rampant habitat destruction by logging, mining, and draining wetlands. Often these activities are done to replace natural landscapes with agriculture - a direct result of population growth.

Nijman V, Shepherd CR (2011) The Role of Thailand in the International Trade in CITES-Listed Live Reptiles and Amphibians. PLoS ONE 6(3): e17825. doi:10.1371/journal.pone.0017825