Monday, December 2, 2013

Two snake genomes

The Burmese python's ability to ramp up its metabolism and enlarge its organs to swallow and digest prey whole can be traced to unusually rapid evolution and specialized adaptations of its genes and the way they work, an international team of biologists says in a new paper. Lead author Todd Castoe, an assistant professor of biology at The University of Texas at Arlington College of Science, and 38 co-authors from four countries sequenced and analyzed the genome of the Burmese python, or Python molurus bivittatus. Their work is scheduled for publication this week (Dec. 2) by the Proceedings of the National Academy of Sciences along with a companion paper on the sequencing and analysis of the king cobra (Ophiophagus hannah). The papers represent the first complete and annotated snake genomes.

Python bivittatus (top), Ophiophagus hannah (bottom)
Because snakes contain many of the same genes as other vertebrates, studying how these genes have evolved to produce such extreme and unique characteristics in snakes can eventually help explain how these genes function, including how they enable extreme feats of organ remodeling. Such knowledge may eventually be used to treat human diseases.

"One of the fundamental questions of evolutionary biology is how vertebrates with all the same genes display such vastly different characteristics. The Burmese python is a great way to study that because it is so extreme," Castoe, who began working on the python project as a postdoctoral fellow at the University of Colorado School of Medicine in the laboratory of associate professor and paper corresponding author David D. Pollock.

Castoe said: "We'd like to know how the snake uses genes we all have to do things that no other vertebrates can do."

The new python study calls into question previous theories that major obvious physical differences among species are caused primarily by changes in gene expression. Instead, it contends that protein adaptation, gene expression and changes in the structure of the organization of the genome itself are all at work together in determining the unusual characteristics that define snakes, and possibly other vertebrates.

Pollock said the python and king cobra studies represent a significant addition to the field of "comparative systems genomics -- the evolutionary analysis of multiple vertebrate genomes to understand how entire systems of interacting genes can evolve from the molecules on up."

He said: "I believe that such studies are going to be fundamental to our ability to understand what the genes in the human genome do, their functional mechanisms, and how and why they came to be structured the way they are."

The Burmese python's phenotype, or physical characteristics, represents one of the most extreme examples of evolutionary adaptation, the authors said. Like all snakes, its evolutionary origin included reduction in function of one lung and the elongation of its mid-section, skeleton and organs. It also has an extraordinary ability for what researchers call "physiological remodeling."

Physiological remodeling refers to the process by which pythons are able to digest meals much larger than their size, such as chickens or piglets, by ramping up their metabolism and increasing the mass of their heart, liver, small intestine and kidneys 35 percent to 150 percent in only 24 to 48 hours. As the digestion is completed, the organs return to their original size within a matter of days. The authors suggest that understanding how snakes accomplish these tremendous feats could hold vital clues for the development of treatments for many different types of human diseases.

"The Burmese python has an amazing physiology. With its genome in hand, we can now explore the many untapped molecular mechanisms it uses to dramatically increase metabolic rate, to shut down acid production, to improve intestinal function, and to rapidly increase the size of its heart, intestine, pancreas, liver, and kidneys," said Stephen Secor, associate professor of biological sciences at the University of Alabama and a co-author on the paper. 'The benefits of these discoveries transcends to the treatment of metabolic diseases, ulcers, intestinal malabsorption, Crohn's disease, cardiac hypertrophy and the loss of organ performance."

To complete their work, the research team aligned 7,442 genes from the python and cobra with genes sequences available in the Ensembl Genome Browser from other amphibians, reptile, bird and mammals. They used a statistical method called "branch site codon modeling" to look for genes that had been positively selected (or evolutionarily changed due to natural selection) in the python, the cobra, and early in snake evolution in the common ancestor of these two snakes. They found changes in hundreds of genes. They believe the results demonstrate that natural selection-driven changes in many genes that encode proteins contributed substantially to the unique characteristics of snakes.

Analyses showed a remarkable correspondence between the function of the selected genes, and the many functionally unique aspects of snake biology -- such as their unique metabolism, spine and skull shape and cell cycle regulation, Castoe said. Many of the altered genes the team observed also have prominent medical significance. For example, the python genome showed some changes to the gene GAB1, which other research suggests plays a role in breast cancer, melanomas and childhood leukemia.

In addition to changes to individual genes and their expression, researchers also found that the extreme characteristics in snakes could also be linked to duplications or losses in multigene families. Some of those include ancient loss and more recent re-evolution of high resolution vision, and their ability to detect chemical cues from the environment. Researchers also observed that, while most assume that reptile genes and genomes change at a very slow rate, snake genomes evolve at one of the fastest rates of any vertebrate.

Citations
Freek J. Vonk, Nicholas R. Casewell, Christiaan V. Henkel, Alysha M. Heimberg, Hans J. Jansen, Ryan J. R. McCleary, Harald M. E. Kerkkamp, Rutger A. Vos, Isabel Guerreiro, Juan J. Calvete, Wolfgang Wüster, Anthony E. Woods, Jessica M. Logan, Robert A. Harrison, Todd A. Castoe, A. P. Jason de Koning, David D. Pollock, Mark Yandell, Diego Calderon, Camila Renjifo, Rachel B. Currier, David Salgado, Davinia Pla, Libia Sanz, Asad S. Hyder, José M. C. Ribeiro, Jan W. Arntzen, Guido E. E. J. M. van den Thillart, Marten Boetzer, Walter Pirovano, Ron P. Dirks, Herman P. Spaink, Denis Duboule, Edwina McGlinn, R. Manjunatha Kini, and Michael K. Richardson. 2013. The king cobra genome reveals dynamic gene evolution and adaptation in the snake venom system. PNAS 2013 ; published ahead of print December 2, 2013, doi:10.1073/pnas.1314702110.

Todd A. Castoe, A. P. Jason de Koning, Kathryn T. Hall, Daren C. Card, Drew R. Schield, Matthew K. Fujita, Robert P. Ruggiero, Jack F. Degner, Juan M. Daza, Wanjun Gu, Jacobo Reyes-Velasco, Kyle J. Shaney, Jill M. Castoe, Samuel E. Fox, Alex W. Poole, Daniel Polanco, Jason Dobry, Michael W. Vandewege, Qing Li, Ryan K. Schott, Aurélie Kapusta, Patrick Minx, Cédric Feschotte, Peter Uetz, David A. Ray, Federico G. Hoffmann, Robert Bogden, Eric N. Smith, Belinda S. W. Chang, Freek J. Vonk, Nicholas R. Casewell, Christiaan V. Henkel, Michael K. Richardson, Stephen P. Mackessy, Anne M. Bronikowsi, Mark Yandell, Wesley C. Warren, Stephen M. Secor, and David D. Pollock. 2013. The Burmese python genome reveals the molecular basis for extreme adaptation in snakes. PNAS 2013 ; published ahead of print December 2, 2013, doi:10.1073/pnas.1314475110


Thursday, November 28, 2013

Sub-lethal skin sections in the wrinkled frog effective against snake predation

Frogs and toads are packets of proteins and calories to many predators. In response anurans have evolved a plethora of defenses against their predators, many of these defenses are chemical. Dendrobatid frogs may kill a potential predators with its defensive toxins, but many species of anurans seem to produce toxins that are sub-lethal. Anuran skin secretions may also have other functions, such as antibacterial protection for their skin. But defensive molecules are abundant in a more or less defenseless group of amphibians.
The Japanese striped snake, Elaphe quadrivirgata,, and the prey it usually avoids, Glandirana (Rana) rugosa.
Photo credit: Alpsdake, and Open Cage.
Some molecules produced by frogs alter the predator's behavior. African clawed frogs  induce yawning and gaping movements in the northern water snake Nerodia sipedon as well as two other natural predators, the African aquatic snakes Lycodonomorphus rufulus and L. laevissimus.

In a new study Yoshimura and Kasuya (2013) examine the impact of the molecules produced by the adult wrinkled frog (Glandirana (Rana) rugosa) which has warty skin with a secretion that has a strong and unique odor. The wrinkled frog is rarely found in the natural diet of the Japanese striped snake (Elaphe quadrivirgata), which is considered a general predator of amphibians, mammals, birds, and reptiles. In a previous study, newborn Japanese striped snake with no prey experience ate few wrinkled frogs. When adult Japanese striped snakes  were forced to swallow wrinkled frogs, all the snakes spat out the frogs and opened and closed their mouths in a gaping behavior. The snake did not change its movements or other behaviors and they did not die shortly after contact with the wrinkle frog. These observations suggested that wrinkled frogs are not highly toxic but that they escape from predation by snakes.

Yoshimura and Kasuya (2013) conducted two experiments to examine whether the skin secretion of adult wrinkled frogs is effective for the evasion of predation by snakes. In the first experiment , they compared the proportion of snakes that bit and swallowed wrinkled frogs with the proportion that bit and swallowed the cricket frog, Fejervarya limnocharis, which resembles wrinkled frogs in size and appearance. In the second experiment they coated the natural prey organisms of the snakes with secretions from the wrinkled frog or the cricket frog to examine the effects of the secretions.

They found the wrinkle frog was less frequently bitten or swallowed by snakes. The snakes that bit wrinkled frog spat out the frogs and showed mouth opening (gaping) behavior, while the snakes that bit the cricket frogs did not show gaping behavior. They also compared the responses of the snakes to wrinkled frogs and F. limnocharis secretions. They coated palatable Rana japonica with secretions from wrinkled frogs or cricket frogs. The frogs coated by wrinkled frog's secretion were less frequently bitten or swallowed than those coated by F. limnocharis secretion. The authors concluded that compared to different frog species of similar sizes, the adult wrinkled frog was less frequently preyed upon by, and that its skin secretion was effective in avoiding predation by snakes.

Yoshimura Y, Kasuya E (2013) Odorous and Non-Fatal Skin Secretion of Adult Wrinkled Frog (Rana rugosa) Is Effective in Avoiding Predation by Snakes. PLoS ONE 8(11): e81280. doi:10.1371/journal.pone.0081280

Wednesday, November 27, 2013

A second look at the Tethyan limbed snakes

Artist's reconstruction of Pachyrhachis problematicus.
Three fossil marine snakes with hind-limbs Pachyrhachis problematicus, Eupodophis descouensi, and Haasiophis terrasanctus. are known from the upper Cretaceous (Cenomanian) of the Middle East. All of them were collected from the region that formed the ancient Tethys Sea. The first species was described in 1979 and a reduced limb lizard,but later recognized as a snake, the others were described in 2000. The phylogenetic status of these snakes has been controversial. In a new paper Palci et al. (2013) have re-evaluated the fossil anatomy of these three species and have drawn some interesting conclusions.  They found no evidence of a laterosphenoid in Haasiophis and Eupodophis; Pachyrhachis and Eupodophis retain a jugal; Haasiophis and Eupodophis, have  chevron bones in the tail; Haasiophis has a large number of unfused intercentra along the anterior portion of the body's vertebral column; and Pachyrhachis has numerous mental foramina on the dentary, as well as at least one sacral vertebra with unfused sacral ribs.

 The authors ran three phylogenetic analyses using alternative out groups (varanoids; iguanians; and skinks+ amphisbaenids, + dibamids) to polarize the character transformations. The in-group consisted of all well-preserved fossil snakes from the Cretaceous, the madtsoiids (mostly Gondwanan snakes with a fossil record extending from the Upper Cretaceous to late Pleistocene from South America, Africa, India, Australia and Southern Europe), and taxa that are representative of all major groups of living snakes. The analyses suggested Pachyrhachis, Eupodophis, and Haasiophis are either a series of stem taxa at the base of the radiation of snakes, or they are members of a clade of fossil snakes that are the sister group to all living alethinopidians (all living snakes minus the scolecophidians).

The authors also found  free intercentra located at the base of the anterior pre-cloacal vertebrae of Haasiophis terrasanctus. If these intercentra are homologous with the cervical intercentra of limbed squamates, this would suggest snakes experienced a considerable amount of axial elongation that involved not only the dorsal but also the cervical region, a point that is supported by the posterior extension of some cervical muscles in snakes. Of interest, a similar pattern of axial elongation as been observed  in dolichosaurs, adriosaurs, and pontosaurs—a group of lizards that have been considered close relatives of snakes since the 19th century. The authors comment that they do not consider these lizards ancestral to snakes, but they may have a close phylogenetic relationship with them.

Citation
Alessandro Palci , Michael W. Caldwell and Randall L. Nydam (2013) Reevaluation of the anatomy of the Cenomanian (Upper Cretaceous) hind-limbed marine fossil snakes Pachyrhachis, Haasiophis, and Eupodophis. Journal of Vertebrate Paleontology, 33:6, 1328-1342.


Monday, November 25, 2013

New species of Neotropical Treerunners in the genus Plica

Treerunners are diurnal, medium sized lizards that sit in the open on vertical surfaces, and are often in small colonies that include adults of both sexes and juveniles. The sounds they make scurrying on the bark of trees or rock outcrops draws attention to their presence and thus, they are common in museum collections.

The tropidurid lizard genus Plica (treerunners) currently contains four species restricted to South America east of the Andes. Two of these are relatively widespread (Plica plica and P. umbra). The other two species are associated with Pantepuis. Plica lumaria is known only from southern Venezuela’s Guaiquinima Tepui, and P. pansticta  from the Yutajé–Corocoro massif of Amazonas, Venezuela.

 Etheridge (1970) restricted the type locality for Lacerta plica Linnaeus to the vicinity of Paramaribo, Suriname, designating NRM.112 as the lectotype. Hoogmoed (1973) further restricted the locality to the confluence of the Cottica River and Perica Creek, Suriname. However, the collared treerunner, Plica plica, is known from the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname, and Venezuela, as well as the islands of Trinidad and Tobago, and including the Bocas Island group Additionally, two specimens collected in the 19th century in the British Museum with the locality data “Grenada.”

Of the four species of Plica currently recognized only P. umbra lacks tufts of spines on the neck; and it has 43–69 scales around mid-body. Plica lumaria is black, the superciliaries are directed laterally, it lacks clusters of spines on the fold below the auditory meatus, and it has 141–156 rows of scales around mid-body and 27–33 lamellae under the fourth toe. Plica pansticta has 143–164 scales around mid-body and 31–39 lamellae under the fourth toe. However, P. plica (sensu Etheridge 1970) has 92–202 scales around mid-body; 21–35 lamellae on the fourth finger and 28–45 lamellae on the fourth toe. The polytypic P. plica has been the subject of ecological, morphological, and phylogenetic studies.

Murphy and Jowers (2013) took another look at Plica plica and uncovered multiple species that have been overlooked. While they focused their work on noethern South America, they did examine specimens from across the distyribution of Plica plica and estimate it contains at least 10 species, four of which are described in the new paper published in ZooKeys.

Caption. (a) Plica caribena sp. n. named for its Caribbean coastal distribution. Photo JCM; (b) Plica rayi named in honor of Ray Pawley for his life long work and interest in herpetology. Photo Zelimir Cernelic; (c) Plica plica. Photo Cesar Barrio Amoros; (d) Plica medemi named after Colombian herpetologist and collector of the specimen Fredico Medem. Photo JCM (e) Plica kathleenae named in honor of Kathleen Kelly, Division of Reptiles, Field Museum. Photo JCM.
The allopatric species described in the paper are associated with northern South American geography. Plica plica is associated with the Guiana Shield (Suriname, Guyana and Venezuela). A second species, P. caribeana sp. n. is associated with the Caribbean Coastal Range of Venezuela including Trinidad and Tobago. A third, very distinctive species, P. rayi sp. n. is associated with the Middle Orinoco at the eastern edge of the Guiana Shield.  Two other species, P. kathleenae sp. n. and P. medemi sp. n., are each based upon a single specimen, one from the Sierra Acarai Mountains of Guyana, and the other from southern Meta, Colombia. In addition to the morphological analyses, they sequenced 12S and 16S rDNA gene fragments from one Plica plica from Trinidad to assess its relationship and taxonomy to other mainland Plica. The results suggest Plica caribeana sp. n. likely diverged prior to the separation of Trinidad from Northern Venezuela. Isolation in the Caribbean Coastal Range during its rapid uplift in the late Miocene, combined with a marine incursion into northern Venezuela may have contributed to their genetic divergence from other populations.

Citation:
Murphy JC, Jowers M. 2013. Treerunners, cryptic lizards of the Plica plica group (Squamata, Sauria, Tropiduridae) of northern South America. ZooKeys

Saturday, November 23, 2013

New study reports US frogs have relatively few abnormalities

A 10-year study shows some good news for frogs and toads on national wildlife refuges. The rate of abnormalities such as shortened or missing legs was less than 2 percent overall — indicating that the malformations first reported in the mid-1990s were rarer than feared. But much higher rates were found in local "hotspots," suggesting that where these problems occur they have local causes. The results were published Nov. 18 in the journal PLOS ONE.

"We now know what the baseline is and the 2 percent level is relatively good news, but some regions need a deeper look," said Marcel Holyoak, professor of environmental science and policy at the University of California, Davis, and a co-author on the study. Hotspot regions included the Mississippi River Valley, California and south-central and eastern Alaska.



Mari Reeves, a graduate student working with Holyoak, led the data analysis and is corresponding author on the paper. Reeves now works at the U.S. Fish and Wildlife Service in Alaska.

Fieldwork for the study was carried out by the Fish and Wildlife Service at 152 refuges across the country between 2000 and 2009. Researchers collected more than 68,000 frogs and toads for the study. The complete dataset is available to researchers and the public online.

The aim of the study was to understand where and when these abnormalities occur — are they widespread, or localized? Are they persistent, or do they appear and fade away? — rather than to identify specific causes, Holyoak said. Understanding the patterns of these hotspots in space and time can help researchers home in on likely causes, he said.

The results show that abnormality hotspots occur in specific places, but within these hotspots the rate of malformations can change over time, Holyoak said.

"We see them at an elevated frequency one year or for a few years, and then they recover," he said.

The most common problems observed were missing or shortened toes or legs, and skin cysts. Only 12 cases of frogs with extra legs were found.

Many different potential causes have been put forward for the abnormalities, including pollution from industry or agriculture, parasites, ultraviolet exposure and naturally occurring heavy metals leaching into water bodies. The exact cause may vary from place to place, Holyoak noted.

The study comes against a background of a general decline in amphibian populations both in the U.S. and worldwide. For example, the California red-legged frog celebrated by Mark Twain's story is now listed as threatened. Frogs and toads may be especially sensitive to changes in climate and air or water quality. It's not clear whether hotspots of malformations contribute to this general decline, Holyoak said, but the new dataset will help researchers explore the problem.

Mari K. Reeves, Kimberly A. Medley, Alfred E. Pinkney, Marcel Holyoak, Pieter T. J. Johnson, Michael J. Lannoo. Localized Hotspots Drive Continental Geography of Abnormal Amphibians on U.S. Wildlife Refuges. PLoS ONE, 2013; 8 (11): e77467 DOI: 10.1371/journal.pone.0077467

Friday, November 22, 2013

Rhinoderma & Bd

Rhinoderma darwinnii. (Photo Credit:
Copyright Claudio Soto-Azat)
Deadly amphibian disease chytridiomycosis has caused the extinction of Darwin's frogs, believe scientists from the Zoological Society of London (ZSL) and Universidad Andrés Bello (UNAB), Chile.
Although habitat disturbance is recognised as the main threat to the two existing species of Darwin's frogs (the northern Rhinoderma rufum endemic to Chile, and the southern Rhinoderma darwinii from Chile and Argentina), this cannot account for the plummeting population and disappearance from most of their habitat.
Conservation scientists found evidence of amphibian chytridiomycosis causing mortality in wild Darwin's frogs and linked this with both the population decline of the southern Darwin's frog, including from undisturbed ecosystems and the presumable extinction of the Northern Darwin's frog.

The findings were published 20 Nov in the journal PLOS ONE.

Professor Andrew Cunningham, from ZSL's Institute of Zoology says: "Only a few examples of the "extinction by infection" phenomenon exist. Although not entirely conclusive, the possibility of chytridiomycosis being associated with the extinction of the northern Darwin's frog gains further support with this study."

Hundreds of specimens of Darwin's frogs and other amphibians from similar habitats collected between 1835 and 1989 were tested in order to find DNA pieces of Batrachochytrium dendrobatidis (Bd), a fungus that causes the disease chytridiomycosis. In addition, 26 populations of Darwin's frogs were surveyed in Chile and Argentina between 2008 and 2012 for the presence of Bd.

Darwin's frogs were named after Charles Darwin who first discovered R. darwinii in 1834 in south Chile during his famous voyage around the globe. The species have a distinct appearance, having evolved to look like a leaf, with a pointy nose. Research leader Dr. Claudio Soto-Azat, from UNAB and former ZSL PhD student says: "Amphibians have inhabited the earth for 365 million years, far longer than mammals. We may have already lost one species, the Northern Darwin's frog, but we cannot risk losing the other one. There is still time to protect this incredible species," Dr Soto-Azat added.

Amphibians provide an important ecosystem service by maintaining balance in the environment. Without them insect plagues and their subsequent effect on agriculture and public health would be more frequent. ZSL scientists are working to further understand the reasons behind the extinction of Darwin's frogs, and ensure the long-term survival of the species.

Citation
Claudio Soto-Azat, Andrés Valenzuela-Sánchez, Barry T. Clarke, Klaus Busse, Juan Carlos Ortiz, Carlos Barrientos, Andrew A. Cunningham. Is Chytridiomycosis Driving Darwin’s Frogs to Extinction? PLoS ONE, 2013; 8 (11): e79862 DOI: 10.1371/journal.pone.0079862


Monday, November 18, 2013

Stretching the lower jaw

The ability of skin and organs to stretch is important in determining the size of prey a snake can swallow. Snake skin consists of a keratinized epidermis divided into thick scale regions and thinner, folded interscale regions that are underlain by a dermis containing a complex array of fibrous connective tissues. In a new study Close and Cundall (2013)  examine the skin of the lower jaw of the northern watersnake, Nerodia sipedon, to determine how skin morphology changes when it is highly stretched during ingestion of large prey.

Biomechanical properties of connective tissue have been relatively well studied and collagen is responsible for much of the skin's ability to resist mechanical failure. In mammalian skin, at low levels of strain (up to about 20%) there is little change in the tissue's mechanical properties because collagen undergoes reorientation prior to stretching and slippage. At increased loads collagen account for skin's viscoelastic properties. However, under prolonged periods of strain, collagen alone is incapable of full recovery from high levels of extension due to irreversible creep. Elastin in the deep dermis has been suggested as being responsible  for skin's elastic behavior, but this has not been supported by in vivo or in vitro studies of mammalian skin. Given the known structure and function of elastin it is likely that elastin in the dermis of snakes is responsible for the refolding of interscale skin and subsequently for returning the skin to its resting condition after prolonged periods of stretch.

The skin and intermandibular soft tissues determine the lower jaw's extensibility and the upper jaws of snakes are limited in the degree to which they can move laterally. Therefore, suspensorial length and mobility, mandible length and lower jaw extensibility are the major determinants of gape size in snakes. Within the context of macrostomy - snakes being able to swallow exceptionally large prey - Cose and Cundall (2013)  examine how snake skin between the two sides of the lower jaw behaves during swallowing and how its function is related to structure.

Video records of skin behavior in the lower jaw of watersnakes feeding on fish or anesthetized watersnakes being stretched on an Instron machine showed that most skin extension involves the interscale skin. The largest intermandibular separation recorded during feeding was 7.7x the resting distance, but intermandibular separation reached 10x without tissue failure during mechanical testing. Histological and anatomical analyses of lower jaws fixed in resting, moderately or highly stretched conditions showed that stretching had little effect on scale regions of the epidermis. However, stretching flattened folds of interscale regions at both gross and cellular levels and imposed changes in epidermal cell shape. Stretching of the dermis is primarily limited to realignment of collagen and stretching of elastin in the deep dermis. The configuration of dermal elastin suggests a model for passive recovery of epidermal folding following release of tension.

Citation
Close M, Cundall D. 2013. Snake lower jaw skin: Extension and recovery of a hyperextensible keratinized integument. J. Exp. Zool. 9999A:1–20.

Tuesday, November 5, 2013

Snakes control blood flow to the spectacle to improve vision

Instead of eyelids, snakes have a clear scale 
called a spectacle. It works like a window, covering 
and protecting their eyes. When presented with a 
threat, the fight-or-flight response changes the spectacle’s
 blood flow pattern, reducing blood flow for longer 
periods than at rest, up to several minutes.
Nov. 4, 2013 — A new study from the University of Waterloo shows that snakes can optimize their vision by controlling the blood flow in their eyes when they perceive a threat.

Kevin van Doorn, PhD, and Professor Jacob Sivak, from the Faculty of Science, discovered that the coachwhip snake's visual blood flow patterns change depending on what's in its environment. The findings appear in the most recent issue of the Journal of Experimental Biology.

"Each species' perception of the world is unique due to differences in sensory systems," said van Doorn, from the School of Optometry & Vision Science.

Instead of eyelids, snakes have a clear scale called a spectacle. It works like a window, covering and protecting their eyes. Spectacles are the result of eyelids that fuse together and become transparent during embryonic development.

When van Doorn was examining a different part of the eye, the illumination from his instrument detected something unusual.

Surprisingly, these spectacles contained a network of blood vessels, much like a blind on a window. To see if this feature obscured the snake's vision, van Doorn examined if the pattern of blood flow changed under different conditions.

When the snake was resting, the blood vessels in the spectacle constricted and dilated in a regular cycle. This rhythmic pattern repeated several times over the span of several minutes.

But when researchers presented the snake with stimuli it perceived as threatening, the fight-or-flight response changed the spectacle's blood flow pattern. The blood vessel constricted, reducing blood flow for longer periods than at rest, up to several minutes. The absence of blood cells within the vasculature guarantees the best possible visual capacity in times of greatest need.

"This work shows that the blood flow pattern in the snake spectacle is not static but rather dynamic," said van Doorn.

Next, the research team examined the blood flow pattern of the snake spectacle when the snake shed its skin. They found a third pattern. During this time, the vessels remained dilated and the blood flow stayed strong and continuous, unlike the cyclical pattern seen during resting.

Together, these experiments show the relationship between environmental stimuli and vision, as well as highlight the interesting and complex effect blood flow patterns have on visual clarity. Future research will investigate the mechanism underlying this relationship.

"This research is the perfect example of how a fortuitous discovery can redefine our understanding of the world around us," said van Doorn.

Citation
K. van Doorn, J. G. Sivak. Blood flow dynamics in the snake spectacle. Journal of Experimental Biology, 2013; 216 (22): 4190 DOI: 10.1242/jeb.093658

Wednesday, October 30, 2013

Snakes, human brains and more evidence for an evolutionary relationship

Was the evolution of high-quality vision in our ancestors driven by the threat of snakes? Work by neuroscientists in Japan and Brazil is supporting the theory originally put forward by Lynne Isbell, professor of anthropology at the University of California, Davis.

In a paper published Oct. 28 in the journal Proceedings of the National Academy of Sciences, Isbell; Hisao Nishijo and Quan Van Le at Toyama University, Japan; and Rafael Maior and Carlos Tomaz at the University of Brasilia, Brazil; and colleagues show that there are specific nerve cells in the brains of rhesus macaque monkeys that respond to images of snakes.

The snake-sensitive neurons were more numerous, and responded more strongly and rapidly, than other nerve cells that fired in response to images of macaque faces or hands, or to geometric shapes. Isbell said she was surprised that more neurons responded to snakes than to faces, given that primates are highly social animals.

"We're finding results consistent with the idea that snakes have exerted strong selective pressure on primates," Isbell said.

Isbell originally published her hypothesis in 2006, following up with a book, "The Fruit, the Tree and the Serpent" (Harvard University Press, 2009) in which she argued that our primate ancestors evolved good, close-range vision primarily to spot and avoid dangerous snakes.

Modern mammals and snakes big enough to eat them evolved at about the same time, 100 million years ago. Venomous snakes are thought to have appeared about 60 million years ago -- "ambush predators" that have shared the trees and grasslands with primates.

Nishijo's laboratory studies the neural mechanisms responsible for emotion and fear in rhesus macaque monkeys, especially instinctive responses that occur without learning or memory. Previous researchers have used snakes to provoke fear in monkeys, he noted. When Nishijo heard of Isbell's theory, he thought it might explain why monkeys are so afraid of snakes.

"The results show that the brain has special neural circuits to detect snakes, and this suggests that the neural circuits to detect snakes have been genetically encoded," Nishijo said.

The monkeys tested in the experiment were reared in a walled colony and neither had previously encountered a real snake.

"I don't see another way to explain the sensitivity of these neurons to snakes except through an evolutionary path," Isbell said.

Isbell said she's pleased to be able to collaborate with neuroscientists. "I don't do neuroscience and they don't do evolution, but we can put our brains together and I think it brings a wider perspective to neuroscience and new insights for evolution," she said.

Citation
Quan Van Le, Lynne A. Isbell, Jumpei Matsumoto, Minh Nguyen, Etsuro Hori, Rafael S. Maior, Carlos Tomaz, Anh Hai Tran, Taketoshi Ono, and Hisao Nishijo. Pulvinar neurons reveal neurobiological evidence of past selection for rapid detection of snakes. PNAS, October 28, 2013 DOI: 10.1073/pnas.1312648110

Tuesday, October 29, 2013

Three new herp species from Queensland

A James Cook University-National Geographic expedition to Cape York Peninsula in north-east Australia has found three vertebrate species new to science and isolated for millions of years -- a bizarre looking leaf-tail gecko, a golden-coloured skink and a boulder-dwelling frog.
Saltuarius eximius

Earlier this year Dr Conrad Hoskin from James Cook University and National Geographic photographer/ Harvard University researcher Dr Tim Laman teamed up for an expedition to explore a remote mountain range on Cape York Peninsula in north-east Australia.

The rugged mountain range of Cape Melville is an amazing place -- millions of black granite boulders the size of cars and houses piled hundreds of meters high. Surveys have previously been conducted in the boulder-fields around the base of Cape Melville but the plateau of boulder-strewn rainforest on top had remained largely unexplored, fortressed by massive boulder walls.

In March this year, with funding from the National Geographic Expedition Council, Hoskin, Laman and a National Geographic film crew flew in by helicopter to explore the uplands. The results were incredible. Within several days they had discovered three highly distinct new vertebrate species (a leaf-tailed gecko, a golden-coloured skink, and a boulder-dwelling frog) as well as a host of other interesting species that may also be new to science.

"Finding three new, obviously distinct vertebrates would be surprising enough in somewhere poorly explored like New Guinea, let alone in Australia, a country we think we've explored pretty well," said Dr Hoskin.
The upland of Cape Melville is a thoroughly isolated rainforest island in a 'sea' of hot, dry forest. The gecko, skink, frog and other rainforest-associated inhabitants have been completely isolated up there for millions of years.

"These species are restricted to the upland rainforest and boulder-fields of Cape Melville. They've been isolated there for millennia, evolving into distinct species in their unique rocky environment," Dr Hoskin said.
The three new species have been named by Dr Hoskin, with the descriptions appearing in October issues of the international journal Zootaxa.

The highlight was the discovery of the leaf-tailed gecko. Leaf-tail geckos are large (20 cm), 'primitive-looking' geckos that are Gondwanan relics from a time when rainforest was more widespread in Australia. The Cape Melville Leaf-tailed Gecko is highly distinct from all relatives and has been named Saltuarius eximius. The species name translates as 'exceptional', 'extraordinary' or 'exquisite', in reference to its unusual form and how distinct it is.

"The second I saw the gecko I knew it was a new species. Everything about it was obviously distinct," said Dr Hoskin.

This spectacular gecko is hidden in the boulders in the day and emerges at night to hunt on rocks and trees. Highly camouflaged, the geckos sit motionless, head-down waiting to ambush passing insects and spiders. Intriguing features of the gecko are its huge eyes and incredibly long and slender body and limbs -- probably all adaptations to life in the dimly lit boulder-fields.

Patrick Couper, Curator of Reptiles and Frogs at the Queensland Museum, and collaborator on the gecko's description, said "That this gecko was hidden away in a small patch of rainforest on top of Cape Melville is truly remarkable."

"What makes it even more remarkable is that two other totally new vertebrates were found at the same time." he said.

"The Cape Melville Leaf-tailed Gecko is the strangest new species to come across my desk in 26 years working as a professional herpetologist. I doubt that another new reptile of this size and distinctiveness will be found in a hurry, if ever again, in Australia."

Saproscincus saltus

The Cape Melville Shade Skink (Saproscincus saltus) was also discovered and described. This beautiful golden-coloured skink is also restricted to moist rocky rainforest on the plateau. It is also long-limbed, but unlike the gecko is active by day, running and jumping across the mossy boulders hunting insects. The species name 'saltus', means 'leaping'. This species is highly distinct from its relatives, which are in rainforests to the south.

Cophixalus petrophilus
Also discovered was a fascinating boulder-dwelling frog, the Blotched Boulder-frog (Cophixalus petrophilus). This small frog is completely restricted to the boulder-fields at Cape Melville. Aptly, its species name means 'rock-loving'. During the dry season the frog lives deep down in the labyrinth of the boulder-field where conditions are cool and moist. In the summer wet season the frog emerges on the surface rocks to feed and breed in the rain.

"You might wonder how a frog's tadpoles can live in a 'hollow' boulder-field with no water sitting around." Dr Hoskin said. "The answer is that the eggs are laid in moist rock cracks and the tadpoles develop within the eggs, guarded by the male, until fully-formed froglets hatch out. As for the gecko, its eyes are very large -- once again an adaptation for life in the dimly lit boulder-piles."

"This frog lives most of its life deep in the boulder-fields where it is dark, cool and moist, and only comes to the surface when it rains." Dr Hoskin said.

Given the discovery of three new vertebrate species, Cape Melville clearly holds many more secrets for future expeditions.

"The top of Cape Melville is a lost world. Finding these new species up there is the discovery of a life time -- I'm still amazed and buzzing from it." said Dr Hoskin.

An illustrated feature story on the expedition can be seen at: http://news.nationalgeographic.com/news/2013/10/131025-lost-world-australia-gecko-frog-skink-science-animals/

Citations
HOSKIN, C. J. (2013). A new skink (Scincidae: Saproscincus) from rocky rainforest habitat on Cape      Melville, north-east Australia. Zootaxa, 3722(3), 385-395.
HOSKIN, C. J. (2013). A new frog species (Microhylidae: Cophixalus) from boulder-pile habitat of Cape  Melville, north-east Australia. Zootaxa, 3722(1), 061-072.
HOSKIN, C. J., & COUPER, P. (2013). A spectacular new leaf-tailed gecko (Carphodactylidae:  Saltuarius) from the Melville Range, north-east Australia. Zootaxa, 3717(4), 543-558.


Thursday, October 24, 2013

Atrazine, Bd, and frog survival

Using the invasive Cuban treefrog, Osteopilius septentrionalis
Rohr et al. studied the effects of atrazine on frogs exposed to Bd.
The combination of the herbicide atrazine and a fungal disease is particularly deadly to frogs. USF Biologist Jason Rohr said  new findings show that early-life exposure to atrazine increases frog mortality but only when the frogs were challenged with a chytrid fungus (Bd), a pathogen implicated in worldwide amphibian declines. The research is published in the new edition of Proceedings of the Royal Society B.

"Understanding how stressors cause enduring health effects is important because these stressors might then be avoided or mitigated during formative developmental stages to prevent lasting increases in disease susceptibility," Rohr said.

The study was conducted by Rohr and Lynn Martin, Associate Professors of USF's Department of Integrative Biology; USF researchers Taegan McMahon and Neal Halstead; and colleagues at the University of Florida, Oakland University, and Archbold Biological Station.

Their experiments showed that a six-day exposure to environmentally relevant concentrations of atrazine, one of the most common herbicides in the world, increased frog mortality 46 days after the atrazine exposure, but only when frogs were challenged with the chytrid fungus. This increase in mortality was driven by a reduction in the frogs' tolerance of the infection.

Moreover, the researchers found no evidence of recovery from the atrazine exposure and the atrazine-induced increase in disease susceptibility was independent of when the atrazine exposure occurred during tadpole development.

"These findings are important because they suggest that amphibians might need to be exposed only to atrazine briefly as larvae for atrazine to cause persistent increases in their risk of chytri-induced mortality," Rohr said. "Our findings suggest that reducing early-life exposure of amphibians to atrazine could reduce lasting increases in the risk of mortality from a disease associated with worldwide amphibian declines."
Until this study, scientists knew little about how early-life exposure to stressors affected the risk of infectious diseases for amphibians later in life.

"Identifying which, when, and how stressors cause enduring effects on disease risk could facilitate disease prevention in wildlife and humans, an approach that is often more cost-effective and efficient than reactive medicine," Rohr said.

The findings are also the latest chapter in research Rohr and his lab has conducted on the impact of atrazine on amphibians. These findings are consistent with earlier studies that concluded that, while the chemical typically does not directly kill amphibians and fish, there is consistent scientific evidence that it negatively impacts their biology by affecting their growth and immune and endocrine systems.

Citation
J. R. Rohr, T. R. Raffel, N. T. Halstead, T. A. McMahon, S. A. Johnson, R. K. Boughton, L. B. Martin. Early-life exposure to a herbicide has enduring effects on pathogen-induced mortality. Proceedings of the Royal Society B: Biological Sciences, 2013; 280 (1772): 20131502 DOI: 10.1098/rspb.2013.1502

Sunday, October 20, 2013

Mechanism of the chytrid fungus

A fungus that is killing frogs and other amphibians around the world releases a toxic factor that disables the amphibian immune response, Vanderbilt University investigators report Oct. 18 in the journal Science.

The findings represent "a step forward in understanding a long-standing puzzle -- why the amphibian immune system seems to be so inept at clearing the fungus," said Louise Rollins-Smith, Ph.D., associate professor of Pathology, Microbiology and Immunology. Although the identity of the toxic fungal factor (or factors) remains a mystery, its ability to inhibit a wide range of cell types -- including cancerous cells -- suggests that it may offer new directions for the development of immuno-suppressive or anti-cancer agents.

The populations of amphibian species have been declining worldwide for more than 40 years. In the late 1990s, researchers discovered that an ancient fungus, Batrachochytrium dendrobatidis, was causing skin infections, and the fungus is now recognized as a leading contributor to global amphibian decline.

Rollins-Smith, an immunologist, and her colleagues have been studying the immune response to the fungus for more than 10 years. "Amphibians have excellent and complex immune systems -- nearly as complex as humans -- and they should be able to recognize and clear the fungus," she said.

In early studies, the investigators demonstrated that some frogs produce anti-microbial peptides in the skin that offer a first layer of defense against the fungus. But when the fungus gets into the layers of the skin, Rollins-Smith said, the conventional lymphocyte (immune cell)-mediated immune response should be activated to clear it.

They found in the current studies that recognition of the fungus by macrophage and neutrophil cells was not impaired. "We think it's not a block at the initial recognition stage," Rollins-Smith said. "The macrophages and neutrophils can see it as a pathogen, they can eat it up, they can do their thing."

But during the next stage of the immune response, when lymphocytes should be activated, the fungus exerts its toxic effects. The investigators demonstrated that B. dendrobatidis cells and supernatants (the incubation liquid separated from the cells) impaired lymphocyte proliferation and induced cell death of lymphocytes from frogs, mice and humans. The toxic fungal factor also inhibited the growth of cancerous mammalian cell lines.

The toxic factor was resistant to heat and proteases (enzymes that cut proteins into pieces), suggesting that it is not a protein. It appears to be a component of the cell wall, because drugs that interfere with cell wall synthesis reduce its inhibitory activity and because the zoospore -- an immature form of the fungus that lacks a cell wall -- does not produce the factor.

The new findings suggest the possibility that toxic factors -- in addition to acting locally to inhibit the immune response -- might also get into the circulation and have neurotoxic effects, Rollins-Smith said.

"Fungal infection causes rapid behavioral changes -- frogs become lethargic and start to crawl out of the water -- suggesting that even though the fungus stays in the skin, the toxic material is having effects elsewhere."

The studies, led by graduate students J. Scott Fites and Jeremy Ramsey, could also suggest new conservation measures for species that may be medically important.

"Amphibian skin has long been favored in folklore for its medicinal properties," Rollins-Smith said. "Frogs are a rich source of potentially useful molecules that might work against human pathogens."

Citation
J. S. Fites, J. P. Ramsey, W. M. Holden, S. P. Collier, D. M. Sutherland, L. K. Reinert, A. S. Gayek, T. S. Dermody, T. M. Aune, K. Oswald-Richter, L. A. Rollins-Smith. The Invasive Chytrid Fungus of Amphibians Paralyzes Lymphocyte Responses. Science, 2013; 342 (6156): 366 DOI: 10.1126/science.1243316

Wednesday, October 16, 2013

Variability in the venom proteome of juvenile Bothrops jararaca

Bothrops jacaraca juvenile. Photo credit: Fernando Tatagiba
Snake venoms are complex mixtures but it is important that we understand them so that we can develop effective antivenoms. For snakes of the viper family, a number of studies have illustrated that the picture is complicated by the fact that the venom composition can vary between members of the same species. These changes are inherited, so have a genetic background.

However, the snake venom of individual viperids also changes with the age and diet of the creatures, so there are other factors at play. These so-called ontogenetic effects are particularly striking in the jararaca, one of the most abundant venomous snakes found in Brazil, which causes many deaths in the local population. This snake, Bothrops jararaca, has caught the attention of Brazilian researchers who have been studying variations in the venom.

Solange Serrano and colleagues from the Butantan Institute, Sao Paulo, and the University of Sao Paulo have found that the proteome of young jararacas differs from that of adults, and that there are gender differences in the venoms too. However, there have been very few studies on juvenile jacaracas, so they undertook a comprehensive proteomic study of the venoms of young snakes in order to define any compositional differences that occur as the juveniles grow.

The research team selected 21 young specimens of Bothrops jacaraca that were born to 10 different mothers originating from different geographical regions of Brazil, all of which were within the states of Sao Paulo, Minas Gerais and Santa Catarina. The mothers were housed in the same lab so that the young could be brought up on exactly the same diet and environmental conditions, to rule out the ontogenetic influences.

Venom was milked from the snakes over 9 months and the proteins were subjected to Western blotting using polyclonal antibodies raised against venom metalloproteinases (SVMPs) and serine proteinases (SVSPs). They were also separated by SDS-PAGE and the proteins in each band were identified by tandem mass spectrometry by searching against the NCBI Serpentes database.

The various properties associated with different venom components, such as caseinolytic, amidolytic and coagulant activity and prothrombin activation, were also investigated and compared between the individual snakes as they matured.

The protein profiles of the snakes showed a wide variation between individuals regardless of gender or the geographical origin of their mothers, even for the eight that were born to the same mother. In addition, the degree of glycosylation of the venom proteins varied between individuals and this was supported by the variations between SVMPs and the SVSPs.

Some of the activities of the venom were similar between snakes while others varied markedly. The abilities to break down casein and activate prothrombin were comparable whereas the amidolytic properties and the plasma coagulant activity differed strongly. So, the variation in the ability to clot the blood of victims, which is a characteristic feature of jararaca venom, cannot be attributed to age, gender or diet and is likely to be a genetic trait.

Although there were large differences in the actual protein compositions, especially within most of the principal toxin classes, there were some areas on the SDS-PAGE bands which were conserved between individuals. For instance, the region corresponding to proteins of molecular mass 45-50 kDa contained SVMPs and L-amino acid oxidase. For 10 venoms, aminopeptidase A was also identified for the first time in the venom of this snake.

A small tripeptide of composition ZKW was also detected in all venoms. This component inhibits SVMPs and acts to prevent the uncontrolled breakdown of proteins within the venom gland.

So, there appears to be a central core of components that are conserved across all jararaca venoms but there are also large variations in the protein compositions. The lack of influence of gender and geographic origin was confirmed by a multivariate analysis. Overall, the findings point strongly to genetic inheritance as the major factor in determining venom composition in juvenile Bothrops jararaca snakes.

Citation
Gabriela S. Dias, Eduardo S. Kitano, Ana H. Pagotto, Sávio S. Sant’anna, Marisa M. T. Rocha, André Zelanis, and Solange M. T. Serrano 2013. Individual Variability in the Venom Proteome of Juvenile Bothrops jararaca Specimens Journal of Proteome Research 2013 12 (10), 4585-4598

Friday, October 11, 2013

New study supports the idea that Cerberus schneiderii is an abundant coastal species

Preliminary studies suggest that Schneider's Bockadam (also known as the dog-faced water snake), Cerberus schneiderii, is one of the most abundant aquatic snakes in mangrove ecosystems across most of Southeast Asia, A new study of this snake at the Sungei Buloh Wetland Reserve in Singapore supports these studies. The brackish man-made ponds at this site do not dry up and they are the source of abundant and continuous food supply to the snakes that inhabit the wetland. The year-round supply of food and climatic conditions allow this snake to grow and reproduce year round. Chim and Dion (2013) conducted monthly surveys at the man-made brackish ponds throughout 2006 and estimated population density  at 102 snakes per hectare and snake biomass at 4.1 kg per hectare. They report relative abundance at 5.4 snakes per man-hour, all  providing evidence of a large Cerberus population at the study site.  A wide range (145–720 mm SVL) of body size were present, and  neonates were rarely encountered. Adult females reach sexual maturity at a body size of 336 mm and the authors found  no seasonal variation in the population’s size structure, suggesting that recruitment occurred throughout the year. Most of the snakes were sedentary and more than 90% of them remained in the same pond that they were captured for the first time. During low tides, snakes had a tendency of congregating in relatively  deep water close to the sluice gates and in the network of tidal streams and pools in the man-made ponds.

Citation
Chim, C. K., & Diong, C. H. (2013). A MARK-RECAPTURE STUDY OF A DOG-FACED WATER SNAKE CERBERUS SCHNEIDERII (COLUBRIDAE: HOMALOPSIDAE) POPULATION IN SUNGEI BULOH WETLAND RESERVE, SINGAPORE. THE RAFFLES BULLETIN OF ZOOLOGY, 61(2), 811-825.

Friday, October 4, 2013

Suizo Report -- To Gus, With Love

Howdy Herpers,                                                         10/3/13

“And when I die, and when I’m gone, there will be one child born in a world to carry on, ......to carry on.” Blood, Sweat and Tears, Columbia Records, 1969

We’re going to go Hollywood with this report. At times, the snakes on our plot demonstrate drama on that sort of scale. We witness sex and violence, interwoven with epic struggles to survive in a land that has barely enough to scratch out a living. Paradise is a nice place to visit, but you wouldn’t want to live there. They have no choice but to make a go of it.

We focus on two snakes with this report. Both are Black-tailed Rattlesnakes (Crotalus molossus). One is a male, CM11, “Gus,” and the other is a female, CM17, “Ms. Gus.”
The slithering duet has much in common, as far as snakes go. They’re both the same species, occupying the same patch of ground. They eat the same prey items, and seek similar shelters. Both have overcome astronomical odds in order to survive to adulthood.  And they both have exceptionally fat heads. Their fat heads are what make them the ideal couple.
 Gus first came our way on 17 September of 2011. At the time, we had little use for a skinny male molossus with a fat head. We’d been there, done that, and had next to nothing to show for it. Hence, he donated some blood, received a PIT tag, and then came the customary unceremonious dump back to his place of capture. He was not even Gus at that point in time. As far as we were concerned, that should have been the end of him.



But then the recapture transpired. On the evening of 3 August 2012, Gus was bagged again. A wave of the PIT tag reader told us who he was. By this point in time, our mission was to put a transmitter into any and all molossus that crossed our path. For whatever reason, our surgeon, Dr. Dale DeNardo, took compassion on this snake. He felt compelled to name this snake after his fat-headed dog, Gus. One must, at times, go to great lengths to take care of the hands that take of them. In short order, Gus was in the game, performing great deeds of Gus-dom. For a scrawny, fat-headed snake, he really got around!  

On 16 September of 2012, Marty Feldner led the field class of Wolfgang Wuster on a Roger-less outing. Gus was found paired with a female­ the future Ms. Gus. The first glimpse of Ms. Gus inspired Marty to comment: “Yegads! Her head is even fatter than his!”  At that point in time, we were out of transmitters. Ms. Gus was left alone that night. As soon as I got wind of the pairing, a rush order for a new transmitter was placed. And the directive was that until we got the transmitter, we were to leave the pair alone. If we were to ever get reproduction of the species on our plot, mating had to ensue.



My first visual of the pair was on the evening of 28 September. They were in a miserable snarl of a packrat midden that was packed into the root system of a particularly sinister and sprawling catclaw acacia. The thorny hell hole was nicely accentuated by a ring of chest high prickly pear which all but blocked the view in. Much blood was lost in trying to get a visual of Ms. Gus. When I finally did see her, I also was inspired to say: “Yegads! Marty is right! Her head is fatter than his!”  

The game of cat and mouse between the fat-headed snakes and their fat-headed trackers continued until the evening of 5 October. That night, Marty and I had split the tracking duties, and Marty had Gus on his route. At 8:09 PM, Marty summed up what he saw nicely by flatly stating on the datasheet: “It is good night to fornicate!” (He didn’t actually write “fornicate.” He used the foo foo word! Cussing on a datasheet? Shame on you, Marty…….)



Despite the rather abrasive start to the words Marty scrawled on the page that night, the rest of the description is as fluid and smooth as the action he witnessed. He wrote:

“CM11 is in coitus with a female (equivalent to his size and maybe heavier) at the edge of a staghorn cholla midden constructed in prickly pear. When first seen, CM11 was head jerking and chin rubbing along flank of unknown female. He continued this behavior on and off for 8-10 minutes until female moved to investigate me. This is when the tails became exposed and I could see for certain that they were locked up. Female dragged him by his wang so they were stretched out in opposite directions, weaved through the prickly pear over the next few minutes. CM11 worked his way back to female and resumed chin rubbing flanks and dorsum, taking breaks periodically to lie motionless and enjoy contemplating which hemipene he was using. Tongue flicking accompanying most chin-rubbing motions.”

Did you guys catch these words?

“FEMALE DRAGGED HIM BY HIS WANG? TAKING BREAKS TO ENJOY CONTEMPLATING WHICH HEMIPENE HE WAS USING?”

How you talk, Feldner!

But just in case, that would be the right hemipene, Gus. Does he know his right from his left? I’ll bet he did on this night!



All joking aside, Marty’s write up of this incident was pure artistry. Working at night with nothing but a headlamp, a clipboard, a pen, a vivid imagination, and a blank page to fill is an arduous process. And the lure of what comes next is always strong with many animals on the list to check. To his credit, he stayed with it.

And so did Gus! The next morning, Mr. Feldner and I did not let any grass grow under our feet getting back to the spot where the action was transpiring. We arrived at 7:55 AM to see that the pair was still “locked up.” This is where our scruples might very well have been in the way of gaining a new study animal. My rules for capture of a new snake do not allow for breaking up a couple that is fu, er uh, fornicating. We were prepared for a long wait. They had already been at it for 12 hours, and could easily go another 12 before it was over. 

But then Ms. Gus did us the ultimate favor. Upon seeing us looming large above her, she panicked, and began sprawling pell-mell toward the entrance to the Neotoma midden that Marty described. Poor Gus was still in her, so to speak, and was haplessly wrapped like an anchor about the prickly pear. Ms. Gus began a series of jerking motions, (yehaw!), trying to get free, but she only gained an inch or so. (Gus’s “wang” also likely gained an inch or so in the process). With a powerful surge, Ms. Gus broke free, literally hanging Gus out to dry in the process.

With Ms. Gus now unconnected, Roger’s rules for breaking up a couple no longer applied. She was snagged and bagged, and female CM17 was now in the game! That’s the end of that story ­and the beginning of the next.

We of course had to take Ms. Gus home with us for a couple days, in order to line up and perform a surgery. This left hapless Gus to smoke his after-sex cigarette alone, and maybe get “righty” back into its proper moorings. After that, he was off to the races. There was no need to be hanging around. The pencil necks had just taken his fu, er uh, his forn, er uh, his mate. No sense in waiting on whatever would come of that flandickery. He bombed across Suzio Wash, and made a major shift along the southern flank of the Suizo Mountains. While there were occasional signs of settling in at a couple places, he never actually hibernated. He stayed on the go throughout the winter, and eventually had moved further north and east than any other animal on our plot. The dude was a machine!


By the time we got Ms. Gus back to her capture spot, Gus was long gone. While it is unlikely that she was pining for her man, she remained at her site 1 for what seemed like two for evers. Finally, on 4 November, she had jetted across the wash, and was near the top of the extensive southwest ridge of the Suizo Mountains proper. She eventually went over top, and dropped into the lower bowels of Tim Canyon. She was viewed surface-active until 4 December. She was very thick in girth at that point. With the next tracking session, 8 December, she had slipped into an impressive and extensive west-facing boulder structure. It was here that she hibernated, and was not seen again until 11 March of 2013.


The author of this epic report decided that a thorough description of the hibernaculum of Ms. Gus is in order. This is not because your author is so fond of typing that he wants to aimlessly go about whittling his fingers to the second knuckle describing a rock pile with a cold snake in it. (Although that is certainly reason enough for the effort). No, this hibernaculum is to play a big role in what follows with this report.

Two paragraphs ago, mention was made of a place called Tim Canyon. This canyon is the southernmost of three different slot canyons that drain the western side of the Suizo Mountains. As one approaches the canyon from the west, it rumbles gently upward in eastward fashion for a distance of about 300 meters. The canyon then bends abruptly, steepens in aspect, and heads upward and northward as one continues the ascent. It eventually peters out, and becomes a steep, south facing flank of the third highest point in the Suizos.

Ms. Gus chose to hibernate at the point where Tim Canyon makes the bend. She was 30% up the east flank of the adjacent slope. The granitic bedrock structure that she selected is roughly three meters tall and nearly perpendicular to the slope, by perhaps three meters wide, and roughly forty  meters long south-to-north. The top portion of this site is actually imbedded in the soil, but the bottom has many crevices and soil holes that lead eastward into its embrace. Lush vegetation grows just west of the bottom of this structure. In short, it was a good place for a fat-headed molossus to be.  


Upon emerging from hibernation, Ms. Gus made a series of mini moves that at first led us to believe that she was going to leave Tim Canyon. She seemed to be retracing her autumnal movements. But once she got to near the top of the southwestern ridge, she began to slip back down again. By 29 June, she was back at her hibernaculum. Marty was able to get two visuals of her in July. With each of these visuals, he commented on how thick she had become toward the rear. 

I did not see her again until 3 August. Up until 3 August, she had remained at her hibernaculum. But with what turned out to be pure serendipity on my part, I found that she had moved about 30 meters northward, along the lower edge of her structure. She was found coiled in a shallow soil escarpment at the northernmost reach of the structure. I had time to squeeze off one photo of her coiled in situ. Then, she bolted into a hole that was just behind her. I squeezed off two more shots of her hefty rear flank before she could slip out of sight. She was, without question, a very pregnant molossus. And this was to be the last time we saw her pregnant. 

By 7 August, she had made a ping pong move back to her hibernaculum. She was not visible, as usual. Two days later, the ever lucky Marty Feldner discovered a male neonate molossus out crawling on top of one of the boulder stacks, less than two meters from where she had hibernated. In short, her hibernaculum was the same place as her parturition site! While this is a common occurrence with many species of rattlesnakes at higher elevations, it is an absolute first for us. This out of 12.5 years of observing birthing with three species of rattlesnake!

Marty and I had not discussed what to do if we encountered any neonates. Hence, on 9 August, he made the executive decision to collect it. His rationale was one of getting DNA from the little fella. There was no hot surge of joy when, on the morning of 10 August, Marty showed me his little prize. I was of course stoked that we had our first birthing incident with molossus, but I had these dreams of seeing piles of babies hanging out with mommy. If we went wading in and removing them as we found them, no such thing would happen. 


Marty was off to other lands in the week that followed. This left me with the nest site of Ms. Gus all to myself. Poor me! There would be no more taking babies from mamma! Needless to say, I hit that rascal morning and night for the next week to follow. I became the invisible man at work and at home. I’d go out and stay out until midnight, get up the following morning at 4 AM and hit it again. While I was doing that, reports and images came trickling in from other parts of the country. In all, three other groups had nesting molossus, and all three got great images of mothers with babies. That’s right, I had these KIDS upstaging me! I was walking a mile a day, twice a day, to attempt to get what they had going on at their back porch. This would have been acceptable if only I got some of the action that should have been my reward.

Nope, when all was said and done, on 12 August, I found one neonate molossus that I had no business finding at all. It was found in a narrow vertical crevice just outside what was determined to be the preferred entrance hole to the nest. Mamma was viewed out basking at this entrance hole on 14 August. Back home, the neonate that Marty had collected shed his skin this day. I took him out to release him at the nest site on 15 August, and captured a Tiger Rattlesnake that was hidden in some trixis and prickly pear close to one of the nest entrances. (I never would have found this tiger were I not scouring the vicinity for neonates). By 16 August, Ms. Gus had cleared out of her nest site, and her birthing experience was behind us. There were to be no cool images of mom and babies hanging out together. No neonate shed skins were found in or around the nest site. While it could have all been worse, despite all the effort, our first molossus birthing experience was a rather lackluster affair. We had a fat snake that morphed into a skinny snake, and two neonates that proved the nesting experience had actually happened.



We did not track Ms. Gus again until 24 August. By this time, she had crawled out of the bowels of Tim Canyon, and was hanging around a wash just east of Iron Mine Hill. It was this wash that Marty first saw her and Gus together. Once she was in this vicinity, I knew it would only be a matter of time before Gus found her. We ramped up our efforts on these two animals accordingly.

For nearly a month, Gus showed no interest in tracking his lady down. They were about 200 meters apart on 31 August, but that was as close together as we saw them. And then, on the evening of 20 September, Dale DeNardo and I tracked Ms. Gus. We found her out crawling in a southerly direction, at the western base of a bump in the bajada that we call “Little Hill.” After tracking her, we joined Marty’s group just as he was finishing the write up of Gus. He was just south of Suizo Wash, close to the northern flank of Iron Mine Hill. He was once again around 200 meters from his lady.

The morning of 22 September found Gordon Schuett, Ryan Sawby, and me close to where Gus had been tracked a day and a half previous. Upon raising the antenna skyward, it was noted that his signal was leading us directly toward where Ms. Gus had last been seen. As we followed the blips, the route was taking us right to the west flank of Little Hill. He seemed to be heading straight for his bride. The flag for Ms. Gus waved in the breeze, just 30 meters to the south. Reunited? Hot diggity damn! Anticipation caused me to ignore the signal, and head for the flag. It was then that it all came to an abrupt end.

“Wait a minute, Roger!” Gordon sounded off from behind me. “Is this what we’re tracking?” As he made the inquiry, he deftly hooked a section of snake flank from out of a prickly pear. It was Gus, or rather, what was left of him.

The 600mm of flank that Gordon had flipped out of the prickly pear was upside down, on open, rocky bajada. Hence, my first glimpse was of the white belly scales facing up. Moderate sized black ants were working both ends of the severed corpse. There was no head or tail to be found in the vicinity, just the hefty mid flank. What remained was fresh, there was no stench, and the ants had barely begun the cleanup process. He had not been dead long.

Next came the photographs, the gut-wrenching mortality write up, and the wild speculation as to how this had happened. Gordon and Ryan heavily favored human predation. My own theory was that this was a natural event. A Harris Hawk was viewed perched high on a nearby mesquite. As we don’t really know for certain what got him, there is no need to belabor the point. What we do know is that a very favored subject of ours is no longer with us. We had grown quite attached to our skinny, fat-headed and randy molossus. You will be missed, Gus.
Meanwhile, in a hallowed drawer of my refrigerator, stowed in a sealed plastic bag is a 300mm plus long full shed skin of a neonate male molossus. Sealed within that bag is a notecard that refers anybody interested to page 19 of the DNA section of the official three-ringed binder of the Suizo Mountain Project for 2013. Page 19 contains all the vitals on this snake. And what the scribe did not capture, the camera did. We have nailed this lad nine ways to Sunday.

 Is this the son of Gus? He sure does have a fat head! This author thinks he is indeed the son of Gus. Will he “carry on?” Though the odds are against him, this author sincerely hopes he does. Will we get him back someday? Maybe!  Will we know him if we do get him? Maybe! Would we have any hope of knowing who he is if Marty had not picked him off from the nest site? No way! 


In light of the full developments of this tale, you done splendid, Mr. Feldner. Let’s hope that one of us lives long enough to see this all draw to a successful conclusion.

This here is Roger Repp, signing off from Southern Arizona, where the turtles are strong, the snakes are handsome, and the lizards are all above average.