2015, Year of the Adder


This video from South Yorkshire in England is called Adders mating (Vipera berus).

2015 is not just the Year of Vincent van Gogh. And the Year of the Penny Bun for mycologists. And the Year of the Goat in the Chinese calendar (starting on 19 February). And the Year of the Badger.

The Dutch RAVON herpetologists have decided that 2015 is the year of the only venomous snake in the Netherlands: the adder. They hope that this year there will be more measures for a better environment for adders, like tunnels enabling them to cross roads.

See also here.

Dutch amphibians and reptiles in winter


This video from France shows a grass snake and an adder together.

Because winter weather has been relatively mild so far in January, some reptiles and amphibians in the Netherlands are already active, Dutch RAVON herpetologists report.

From 1 till 19 January 2015 were seen: two adders; four slow worms; eight Alpine newts; fifteen great crested newts; twenty smooth newts; eighteen common toads; 35 common frogs; one moor frog; six edible frogs; one red-eared slider turtle; and one loggerhead sea turtle.

Biodiversity, including small predators such as dragonflies and other aquatic bugs that attack and consume parasites, may improve the health of amphibians, according to a team of researchers. Amphibians have experienced marked declines in the wild around the world in recent decades, the team added: here.

Dutch reptiles use life-saving tunnel


This video is about reptiles in France and Tunisia.

In 2009, herpetologists designed a special wildlife corridor for reptiles and amphibians, a ‘herpetoduct‘ for nature reserve Elspeetsche Heide in the Netherlands.

It is a tunnel under the N310 motorway and a bicycle track, preventing crossing animals from being killed by traffic.

Research at various times in 2012-2014 proves much wildlife, especially lizards, use the tunnel. 16 viviparous lizards used the tunnel. Once, even at least five young viviparous lizards were born in the tunnel. Other species: four sand lizards; one slow worm; two adders; one moor frog; one European toad; one Alpine newt. Also, one smooth snake was seen.

Results of the research were published in the Zeitschrift für Feldherpetologie.

How some snakes became venomous, new research


This video is called The Evolution of Venom – Who is The Most Poisonous? [Full Documentary]

From the University of Texas at Arlington in the USA today:

Team proposes new model for snake venom evolution

17 hours ago

Technology that can map out the genes at work in a snake or lizard‘s mouth has, in many cases, changed the way scientists define an animal as venomous. If oral glands show expression of some of the 20 gene families associated with “venom toxins,” that species gets the venomous label.

But, a new study from The University of Texas at Arlington challenges that practice, while also developing a new model for how snake venoms came to be. The work, which is being published in the journal Molecular Biology and Evolution, is based on a painstaking analysis comparing groups of related genes or “gene families” in tissue from different parts of the Burmese python, or Python molurus bivittatus.

A team led by assistant professor of biology Todd Castoe and including researchers from Colorado and the United Kingdom found similar levels of these so-called toxic gene families in python oral glands and in tissue from the python brain, liver, stomach and several other organs. Scientists say those findings demonstrate much about the functions of genes before they evolved into venoms. It also shows that just the expression of genes related to venom toxins in oral glands of snakes and lizards isn’t enough information to close the book on whether something is venomous.

“Research on venom is widespread because of its obvious importance to treating and understanding snakebite, as well as the potential of venoms to be used as drugs, but, up until now, everything was focused in the , where venom is produced before it is injected,” Castoe said. “There was no examination of what’s happening in other parts of the snake’s body. This is the first study to have used the genome to look at the rest of that picture.”

Learning more about venom evolution could help scientists develop better anti-venoms and contribute to knowledge about gene evolution in humans.

Castoe said that with an uptick in genetic analysis capabilities, scientists are finding more evidence for a long-held theory. That theory says highly toxic venom proteins were evolutionarily “born” from non-toxic genes, which have other ordinary jobs around the body, such as regulation of cellular functions or digestion of food.

“These results demonstrate that genes or transcripts which were previously interpreted as ‘toxin genes’ are instead most likely housekeeping genes, involved in the more mundane maintenance of normal metabolism of many tissues,” said Stephen Mackessy, a co-author on the study and biology professor at the University of Northern Colorado. “Our results also suggest that instead of a single ancient origin, venom and venom-delivery systems most likely evolved independently in several distinct lineages of reptiles.”

Castoe was lead author on a 2013 study that mapped the genome of the Burmese python. Pythons are not considered venomous even though they have some of the same genes that have evolved into very toxic venoms in other species. The difference is, in highly venomous snakes, such as rattlesnakes or cobras, the venom gene families have expanded to make many copies of those shared genes, and some of these copies have evolved into genes that produce highly toxic venom proteins.

“The non-venomous python diverged from the snake evolutionary tree prior to this massive expansion and re-working of venom gene families. Therefore, the python represents a window into what a snake looked like before venom evolved,” Castoe said. “Studying it helps to paint a picture of how these gene families present in many vertebrates, including humans, evolved into deadly toxin encoding genes.”

Jacobo Reyes-Velasco, a graduate student from Castoe’s lab, is lead author on the new paper. In addition to Castoe and Mackessy, other co-authors are: Daren Card, Audra Andrew, Kyle Shaney, Richard Adams and Drew Schield, all from the UT Arlington Department of Biology; and Nicholas Casewell, of the Liverpool School of Tropical Medicine.

The paper is titled “Expression of Venom Gene Homologs in Diverse Python Tissues Suggests a New Model for the Evolution of Snake Venom.” It is available online here.

The research team looked at 24 gene families that are shared by pythons, cobras, rattlesnakes and Gila monsters, and associated with venom. The traditional view of venom evolution has been that a core venom system developed at one point in the evolution of snakes and lizards, referred to as the Toxicofera, and that the evolution of highly venomous snakes, known as caenophidian snakes, came afterward. But little explanation has been given for why evolution picked just 24 genes to make into highly toxic venom-encoding genes, from the 25,000 or so possible.

“We believe that this work will provide an important baseline for future studies by venom researchers to better understand the processes that resulted in the mixture of toxic molecules that we observe in venom, and to define which molecules are of greatest importance for killing prey and causing pathology in human snakebite victims,” Casewell said.

When they looked at the python, the team found several common characteristics among the venom-related gene families that differed from other genes. Compared with other python gene families, venom are “expressed at lower levels overall, expressed at moderate-high levels in fewer tissues and show among the highest variation in expression level across tissues,” Castoe said.

“Evolution seems to have chosen what genes to evolve into venoms based on where they were expressed (or turned on), and at what levels they were expressed,” Castoe said.

Based on their data, the new paper presents a model with three steps for venom evolution. First, these potentially venomous genes end up in the oral gland by default, because they are expressed in low but consistent ways throughout the body. Then, because of natural selection on this expression in the oral gland being beneficial, tissues in the mouth begin expressing those genes in higher levels than in other parts of the body. Finally, as the venom evolves to become more toxic, the expression of those genes in other organs is decreased to limit potentially harmful effects of secreting such toxins in other body tissues.

The team calls its new model the Stepwise Intermediate Nearly Neutral Evolutionary Recruitment, or SINNER, model. They say differing venom levels in snakes and other animals could be traced to the variability of where different species, or different genes within a species, are along the continuum between the beginning and end of the SINNER model.

Castoe said the next step in the research would be to examine the genome of highly venomous snakes to see if the SINNER model bears out. For now, he and the rest of the team hope that their findings about the presence of venom-related in other parts of the python change some thinking on what species are labeled as venomous.

“What is a venom and what species are venomous will take a lot more evidence to convince people now,” Castoe said. “It provides a brand new perspective on what we should think of when we look at those oral glands.”

Which snake species is most venomous?


This video from the USA is called A discussion of the biology, ecology, conservation and scientific illustration of the Eastern Indigo Snake (Drymarchon couperi) with an introduction of scientific illustration. Given by Mark Mandica, Amphibian Conservation Coordinator @ the Atlanta Botanical Garden‘s Science Café (July 18th 2013).

This species is not venomous.

From National Geographic:

Weird Animal Question of the Week: What’s the Most Toxic Snake?

Technically, it’s the inland taipan—but other snakes are more dangerous.

By Liz Langley

December 6, 2014

Snakes are sneaky-even questions about them can wiggle right out of your grasp.

When Arocha Musa of Kampala, Uganda, wrote in asking, “What makes the cobra the most dangerous snake?” we quickly realized two things: Cobras aren’t considered the most dangerous snake, and finding out which is poses a challenge. (Learn more about the world’s deadliest snakes on Nat Geo WILD.)

“If you’re playing Trivial Pursuit, the answer is the inland taipan,” quips Kate Jackson, a biologist at Whitman College in Walla Walla, Washington.

That’s because the inland taipan has both the most toxic venom and injects the most venom when it bites. A native of Australia that’s also called the “fierce snake,” the inland taipan packs enough venom to kill a hundred men in one bite, according to the Australia Zoo.

The standard measurement used to calculate venom potency is called lethal dosage, with an LD50 defined as what it would take to kill half a population of laboratory animals, usually mice.

Neurotoxic snake venom works by paralyzing the victim’s muscles, which in turn leads to respiratory arrest; hemotoxic venom works by breaking down the tissues. (Read about National Geographic venom expert Zoltan Takacs.)

The lower the LD50, the less venom it takes-meaning the more potent the venom.

The Australia Venom Research Unit keeps a list of the 25 snakes with the lowest LD50-which are thus the most toxic. The top five are the inland taipan, the eastern brown snake, the coastal taipan, the tiger snake, and the black tiger snake.

How Toxic? It Depends

Real life isn’t so simple. Both Jackson and Steven Seifert, director of the New Mexico Poison and Drug Information Center, emphasize that there are many other circumstances beyond potency that make a snake dangerous, such as the availability of health care and antivenom following a snakebite.

As Seifert puts it, “The most venomous snake is the one that bites you.”

According to the Global Snakebite Initiative, snake bites cause about 125,000 deaths a year worldwide. People get bit more often when they’re working outside or must be in places where contact with snakes is unavoidable, Seifert noted.

“In the U.S., about half the bites are truly accidental, and the other half are people intentionally interacting with snakes,” such as moving them or trying to capture them, he said. (Related: “Year of the Snake: The Serpent Behind the Horoscope.”)

In West Africa, the saw-scaled viper or carpet viper thrives among humans, in particular feeding on rats in urban slums, Jackson said.

That translates to more bites, since “there are a lot of people going around barefoot and who don’t have access to the treatment for snakebite.”

Widely distributed and highly venomous, Africa’s puff adder blends in well with its surroundings, making it more likely to be stepped on. The species is thought to kill the most people in Africa.

India bears the brunt of snakebites, with the highest number of bites and resulting deaths, in part because of lack of adequate health care, according to a 2008 study published in PLOS Medicine.

For instance, India’s Russell’s viper isn’t high on the most-toxic list, but it’s responsible for thousands of deaths annually in the country, Jackson noted.

On the other hand, the highly toxic inland taipan lives in the middle of the desert, where few people are found.

This lifestyle and Australia’s good infrastructure, health care, and transportation are why there have been no recorded deaths attributed to the species.

Stand and Spit

None of this should minimize the mighty cobra, however.

There are about 30 species of these impressive reptiles, including the world’s largest venomous snake, the king cobra.

“Cobras are part of the Elapidae family, which includes all the Australian snakes, the taipan, the krait, [and] the mamba,” Seifert said. (See National Geographic‘s pictures of snakes.)

All cobra species “stand” and flare that recognizable hood, a flap of skin behind the head that’s expanded with air from their lungs to make them look bigger.

Some cobras can even spit venom up to 8 feet (2.4 meters) away. (Related: “Cobras Spit Venom at Eyes With Nearly Perfect Aim.”)

At the end of the day, when dealing with snakes in the wild, experts recommend that you leave them be-but appreciate them from afar.

Which snake is Africa’s deadliest? Here.

How grass snakes changed from protective deities to Satan


This video says about itself:

This young grass snake was sleeping with slow worms.

From Environment and History, Volume 20, Number 3:

The Grass Snake and the Basilisk: From Pre-Christian Protective House God to the Antichrist

Abstract:

The grass snake owes its far northern distribution in Europe to the production and hoarding of dung from stock breeding. Dung heaps appear to be perfect breeding sites that surpass ‘natural’ reproduction sites in quality. Here we point out that the grass snake‘s dependency on manure goes back to Neolithic times and that it had a reciprocal cultural effect.

Moreover, the positive influence of humans on the species not only resulted from physical opportunities offered by agriculture, but also from the fact that grass snakes were considered to be chthonic deities not to be harmed.

The conversion of Europe to Christianity, however, marked the turning of the cultural tide for the species. From being a divine creature originally, the grass snake evolved into the number one symbol of the Anti-Christ: the basilisk.

In spite of the subsequent witch-hunt motivated by Christian belief, the overall historical human influence on the species was certainly not detrimental as regarded geographical distribution opportunities. This historical perspective on grass snake-human relationships adds to the discussion of whether nature conservation is better served by a strategy of land sparing or of land sharing.

It also makes clear not only that co-dependency of species is a matter of mutual biophysical advantages but that metaphysical considerations may also play a role. In this case it leads to the conclusion that bringing back the grass snake into our direct everyday surroundings is both favourable to the grass snake and reinstates the species in our own cultural environment.