Thursday, November 18, 2010

Tiny and Toxic


Eleutherodactylus iberia
In 1998, John W. Daly at the National Institutes of Health noted that amphibian skin contains a wide range of biologically active molecules and that in three decades (since 1968) more than 400 alkaloids in more than 20 structural classes have been detected. But perhaps most surprising, the alkaloids in amphibian skins were not made by the amphibians' cells, instead they were molecules hijacked from the arthropods the amphibians ate. Many of these molecules are used as defense against micro-organisms and predators. Other amphibian skin molecules are biosynthesized by the animal's own cells. But the alkaloids particularly those that are lipid soluble are made in the arthropod prey or possibly by symbiotic micro-organisms and stored in the amphibian's skin glands. Twelve years after Daly's paper more than 800 molecules have been identified.

But not all amphibians can take molecules from their prey and use them for their own defense. Perhaps the Neotropical poison-dart frogs (Dendrobatidae) are best known for this ability. Poison dart frogs kept in captivity and feed a diet a fruit flies are no longer poisonous. But there are other anurans that do this: the South American Red bellied Toads (genus Melanophryniscus, family Bufonidae); one genus of Madagascan Golden Frogs (Mantella, family Mantellidae); and one genus of Australian Toadlets (Pseudophryne, family Myobatrachidae). Minor quantities of alkaloids have also been found in the Asian genus Limnonectes (family Dicroglossidae) but it is unknown if they are also getting the alkaloid molecules from their food. Thus, the frogs that do sequester alkaloids from their prey are un-related, but they all tend to have aposematic coloration that signals predators that they are toxic.

Now, Ariel Rodriguez and colleagues (2010) report a 5th lineage of frogs that obtain defensive molecules from their prey, the minute Cuban, Eleutherodactylus iberia and Eleutherodactylus orientalis, (family Eleutherodactylidae). During recent fieldwork, the odor of dissected specimens reminded the authors of the alkaloid-containing dendrobatid and mantellid species. Further investigation provided conclusive evidence that these aposematic frogs contain lipid soluble alkaloids of the same compound classes previously reported in other alkaloid-containing frog lineages. The authors found six pumiliotoxins and two indolizidines in E. iberia but cannot confirm that alkaloid sequestering is characteristic for all populations of E. Iberia. And they are unsure whether it regularly occurs in E. orientalis and other related species of the E. limbatus group without extensive additional effort. However, the discovery that at least some of these frogs sequester lipid-soluble alkaloids may contribute to the understanding of the evolutionary pathway to alkaloid-sequestration and aposematism in amphibians. Examination of stomach contents indicated an abundance of oribatid mites, a group of arthropods known to contain one of the pumiliotoxins detected in E. iberia. This suggests that miniaturization and specialization to small prey may have favored the acquisition of dietary skin alkaloids in these amphibians. 

Of interest is the discovery that oribatid mites are a common prey for miniaturized frogs including the miniature Eleutherodactylus examined in this study. The two alkaloids of E. iberia have previously been detected in arthropods (mites and ants).  Additional evidence for the importance of miniaturization came from the phylogenetic position of the poorly known Wakea madinika, a dwarf frog from Madagascar, as the sister group of the alkaloid-containing genus Mantella, which might indicate that the Mantella ancestor was also miniaturized. The miniature Cuban Eleutherodactylus are largely diurnal, and aposematic in coloration. Other species in the same clade have a much less contrasted coloration and this group of frogs may be useful in understanding  how diet, miniaturization, the ability to sequester alkaloids, and changing daily activity patterns evolve together.

Literature
Daly, J. W. 1998. Thirty Years of Discovering Arthropod Alkaloids in Amphibian Skin. Journal of Natural Products 61:162-172.

Rodríguez, A., Poth, D., S. Schulz, and M. Vences. 2010. Discovery of skin alkaloids in a miniaturized eleutherodactylid frog from Cuba. Biology Letters doi: 10.1098/rsbl.2010.0844

Wednesday, November 17, 2010

Asia: Why Snake Bite Matters

The following story was published by IRIN today. IRIN – stands for Integrated Regional Information Networks – has its head office in Nairobi, Kenya, with regional desks in Nairobi, Johannesburg, Dakar, Dubai and Bangkok, covering some 70 countries. IRIN is an award-winning humanitarian news and analysis service covering the parts of the world often under-reported, misunderstood or ignored. The story is un-edited by me. However, the article was accompanied by a photo with the caption "Venomous viper rattlesnake at Snake Farm in Thailand. Snake-bites, which kill more than 300 people around the world every day, are considered a neglected tropical disease by the World Health Organization." The snake in the photo appears to be a Coelognathus radiata. JCM

BANGKOK, 17 November 2010 (IRIN) - Despite an age-old widespread fear and distrust of snakes, their bites have only recently been added to the World Health Organization’s (WHO) list of “neglected tropical diseases”.

Snakes bite an estimated five million people each year worldwide, seriously injuring or disabling up to three million and killing an estimated 125,000, according to WHO and the Australian Venom Research Unit (AVRU).

Snake bites cause more death and disability than some far more notorious tropical diseases, including dengue fever, cholera, Japanese encephalitis, Chagas disease and leishmaniasis, according to WHO.

“In some provinces of Papua New Guinea, the rate of death due to snake bite is two times higher than malaria,” said David Williams, coordinator of the Global Snakebite Initiative, a Melbourne-based global research project.

Roughly half the world’s snakebites occur in Asia, mostly in India, which has the largest snake bite problem in the world, with up to 50,000 people bitten every year.

“Snake bites are a widespread problem in this region particularly for the poorer populations,” Williams said.

Accurate figures for Asia are difficult to ascertain, since many bites are never reported. “The people who are most affected by snake bites are poor rural farmers. They often can’t afford or don’t have access to national healthcare facilities so turn to informal local healers instead,” said Williams.

Work hazard

Sombat Kaewsaeng, a 45-year-old gardener, was cutting the grass in central Bangkok where he lives and works when he suddenly felt a sharp pain on the top of his right foot.

“I thought it might be a bug or something, but then I saw something slithering away in the grass and looked down and saw two fang markings half a centimetre deep in the top of my foot,” he said.

Sombat, who only works in flip-flops, used a rope to tourniquet his knee and went immediately to the hospital.

“I saw on TV that this was what to do when you get bit,” he said. “As soon as I got to the hospital [30 minutes later] they immediately identified that it was non-venomous, much to my relief.”

Gardeners, agriculture workers and snake handlers - those most likely to invade the habitat of snakes - are the most likely people to be bitten. So much so that WHO considers snake bites an “occupational hazard”.

“Snakes only bite when they are afraid,” said Montri Chiobamroonkiat, head of the Bangkok-based “Snake Farm”, a WHO Collaborating Centre for Venomous Snake Toxicology and Research located in the Queen Saovabha Memorial Institute (QSMI).

QSMI, the primary snake toxicology research unit in Thailand, holds annual conferences with healthcare workers across the country and produces some 100,000 anti-venom treatment vials annually.

Deaths by snake bites sharply increase during and following monsoon seasons - periods of peak agricultural activity.

Sharp rises in the number of snake bite victims have been reported from India, Bangladesh and Myanmar, typically after heavy flooding as large work forces re-built roads or dug irrigation.

Aid agencies reported dramatic increases in snake-bite victims in the year following Cyclone Nargis in Myanmar.

In order to reduce the number of people killed or disabled by snake bites each year, experts say countries need to educate health service employees about how to treat snake-bites, as well as produce anti-venoms.

“The biggest challenge in the past was getting the right diagnosis [venomous or not] but now the region needs to make available anti-venoms,” said Suchai Suteparuk, associate director of the QSMI’s Snake Farm.

Williams pointed out regional disparities in managing snake bites.

Snakes kill less than 10 people every year in Thailand, out of the some 10,000 people bitten, while 500-1,000 people die annually from snake bites in neighbouring Myanmar, though about the same number are bitten.

The situation has worsened to the point the Myanmar Ministry of Health in 2010 set a five-year plan with annual targets for the reduction of snake bites.

Meanwhile, even a Bangkok snake research institute cannot protect gardeners like Sombat from risk. “I will be more careful now when working. I’m much more afraid lately when I’m working in the garden,” he said.

Geothermal Powered Snakes?


Frank Wall entered the Indian Medical Service in 1893 and spent most of the next 33 years as a British Medical Officer in the Indian Empire, being stationed in Ceylon, Burma, and peninsular India. In the First World War he joined an expeditionary force in Iraq and also served in France. Wall was interested in all aspects of snakes, and he wrote about 215 titles between 1898 and 1928. As he traveled, he obtained specimens from others, sometimes paying local people small sums for specimens, encouraging them to collect. In 1907, Wall described Natrix baileyi on the basis of two specimens he obtained from Lieutenant F. M. Bailey. The only locality data Wall provided in the original description was that the snakes came from Tibet and were collected at about 14,000 feet elevation. The specimens were given to the British Museum of Natural History, with a note saying they came from “above Gyantze, at 14,000 feet altitude.”  Wall reported that the specimens were found "in the sides of a hot spring, and are never found as far as half a mile distant… they are reported not to enter the water, and can be obtained in winter and summer alike." One female (903 mm) contained six eggs. Edward Malnate moved Natrix baileyi to the new genus Thermophis when he examined the snake’s anatomy and found it quite distinct from other snakes in the genus Natrix. Guo et al. (2008) described a second species of Thermophis, T. zhaoermii. Both species are endemic to the Qinghai-Xizang Plateau, with Thermophis baileyi on western side of Mt. Hengduan, while T. zhaoermii inhabits its eastern side. Both species occur at relatively high elevations (about 4350 m). Thus, Thermophis may reach the highest altitude of any snakes and undoubtedly holds the altitude record for Asian snakes.

Huang et al. (2009) conducted a phylogenetic analysis to identify the closest related living relative of the Hot Spring snakes using mitochondrial DNA sequences from eight specimens, together with sequences from 95 additional caenophidian and five henophidian genera that were obtained from GenBank. Results showed the hot-spring snakes, species adapted to high, cold environments, clustered in the monophyletic, New World Xenodontinae (now in the family Dipsadidae). Their data failed to provide any evidence that the New World xenodontines diverged from Thermophis and dispersed into the New World, and also failed to suggest a colonization of Asia by New World xenodontines by dispersal from the New World. But perhaps more importantly than shedding light on the ancient relationships of this snake, Huang et al. (2009) also showed the divergence of the two species in Thermophis was caused by the barrier formed by the Hengduan Mountains, and that speciation had almost occurred when Tibetan Plateau attained present elevation.

Using both mtDNA and a nuclear gene, He et al. (2009) suggested again that  Thermophis does appear to be a member of the Western Hemisphere Xenodontinae, And their molecular data also indicate a large genetic distance between T. baileyi and T. zhaoermii, which strengthened the validity of the recently described, T. zhaoermii. In a more recent paper, He et al. (2010) used the complete mitochondrial genome sequence of the Sichuan hot-spring keel-back (Thermophis zhaoermii), and recovered Thermophis as a Colubridae and the sister to the Colubrinae. In an early on-line view Pyron et al. (2010) recovered Thermophis as the sister taxon to the colubrid pseudoxenodontinae genera Plagiopholis and Pseudoxenodon, (both South and Southeast Asian high elevation snakes, (being found up to 1300 m and 2000 m respectively - not nearly as high as Thermophis) and they consider Thermophis to be part of Pseudoxenodontinae.Geographically, this is a much more satisfactory relationship.

What is missing here is the natural history of Thermophis. We think it lays eggs - but might Wall have only seen un-shelled, ovarian or oviducal eggs?  Its diet, habitat use, and thermal ecology are unknown. Wall's comment that it can be found year round  (at at 14,000 ft - more than 4000 m) and that it never wanders far from hot springs is tantalizing. Is Thermophis able to survive the cold temperatures of winter at high altitudes  because of the geothermal energy in its environment? Could the two species of Thermophis be the first known snakes to rely not on solar power, but on geothermal energy, for regulating  body temperature?

This is not as farfetched as it may seem. Recently Loval et al. (2010) described an aquatic moss (Fontinalis) colony closely associated with vent emissions at the bottom of Yellowstone Lake that considerably exceeded known temperature maxima for this plant. The moss was colonized by animals, including crustaceans (Hyalella and Gammarus), a segmented worm in the Lumbriculidae family, and a flatworm tentatively identified as Polycelis. The presence of these invertebrates suggest a highly localized food chain derived from the presence of geothermal energy and that support significant biodiversity.

Literature
Guo, P., S.-Y. Liu, J.-C. Feng, M. He. 2008. The description of a new species of Thermophis (Serpentes: Colubridae). Sichuan Journal of Zoology, 27(3). [In Chinese, English summary].
He, M., J.- C. Feng; S.-Y. Liu, P. Guo, E. Zhao.  2009. The phylogenetic position of Thermophis (Serpentes: Colubridae), an endemic snake from the Qinghai-Xizang Plateau, China. Journal of Natural History, 43:479-488.
He, M., J. Feng, and E. Zhao.  2010. The complete mitochondrial genome of the Sichuan hot-spring keel-back (Thermophis zhaoermii; Serpentes: Colubridae) and a mitogenomic phylogeny of the snakes. Mitochondrial DNA 21:8-18. (I have only seen the abstract of this paper).
Huang, S. S. Liu, P. Guo, Y. Zhang and E. Zhao. 2009. What are the closest relatives of the hot-spring snakes (Colubridae, Thermophis), the relict species endemic to the Tibetan Plateau? Molecular Phylogenetics and Evolution, 51(3):438-446. 
Lovalo, D., S. R. Clingenpeel, S. McGinnis, R. E. Macur, J. D. Varley, W. P. Inskeep, J. Glime, K. Nealson, and T. R. McDermott. 2010. A geothermal-linked biological oasis in Yellowstone Lake, Yellowstone National Park, Wyoming. Geobiology, 8:327–336.
Malnate, E. 1953.The Taxonomic Status of the Tibetan Colubrid Snake Natrix baileyi, Copeia (2):92-96
Pyron, A. R., F. T. Burbrink, G. R. Colli, A. N. Montes de Oca, L. J. Vitt, C. A. Kuczynski and J. J. Wiens. 2010. The phylogeny of advanced snakes (Colubroidea), with discovery of a new subfamily and comparison of support methods for likelihood trees. Molecular Phylogenetics and Evolution, In Press, doi:10.1016/j.ympev.2010.11.006.
Wall, F. 1907. Some new Asian snakes. Journal of the Bombay Natural History Society 17(3): 612-618. 
Zhao, E. 2008. Hot-Spring Snakes, The Snakes Endemic to Qinghai-Xizang Plateau. Journal of the Central University for Nationalities (Natural Sciences) [in Chinese, abstract in English].

Tuesday, November 16, 2010

Dwarf Chameleons, Brookesia, Some Recent Research


A composite of a series of video images illustrating how the Malagasy dwarf
chameleon’s tail curls and contacts the substrate during locomotion.
The Malagasy Dwarf Chameleons (Brookesia sp) are unusual for several reasons. They are exceptionally small for members of the Chamaeleonidae, they are very terrestrial (most chameleons are very arboreal), they have very short tails (most chameleons have relatively long tails), and they have bodies that mimic dried leaves. Several recent papers report on some interesting aspects on these interesting lizards.

Boistel et al. (2010) examined the walking behavior of these lizards and found that while they have grasping feet used to hold on to narrow substrates, they also place the tail on the substrate when walking on broad substrates to improve their stability. Using three-dimensional synchrotron X-ray phase-contrast imaging, the authors demonstrate a set of unique specializations in these unusual lizards. 3D reconstructions of the vertebrae inside the tail show morphological specializations that explain this ability. The tail tip is relatively mobile because there are fewer and finer vertebrae with stronger ventral tendons. The tail is therefore able to bend and provide the chameleon with a fifth point of contact with the ground. The inner ear morphology also is involved in balance. It has a highly specialized structure so that the ear could be adapted to detecting weak accelerations and help to correct posture. The high-resolution images obtained at the ESRF (The European Synchrotron Radiation Facility) were crucial in order to visualize the tail tendons, this could not have been accomplished with conventional X-ray technology. Also, the detailed reconstruction of the inner ears enabled precise comparison of the subtle structures within each species’ ear. The authors point out that it will be interesting to compare Brookesia's adaptations with those of genus Rhampholeon, an independent lineage of small ground-dwelling chameleons to test whether a similar tail-assisted locomotor mechanism is present.

Randrianantoandro et al. (2010) examined the abundance of chameleons at eight locations in Madagascar and found that in deciduous forest in Menabe, western Madagascar. Brookesia brygooi was the most abundant species, with a population density estimated at  35 per hectare. Furcifer species were less common, with densities of  about 7.2 per hectare for F. labordi, 3.0 per hectare for  Furcifer sp. and 1.3 per hectare F. oustaleti. Abundance of B. brygooi varied with altitude and the authors did not detect any clear problems created by logging. However, a lack of information about the chameleons diurnal habitat use is needed to assess the tolerance of these lizards to forest degradation. However, Rakotondravony et al. (2010) report that common species in original forest (e.g., Brookesia) were completely lacking in fragments.

Andrews and Karsten (2010) examined molecular phylogenies of chameleons and found that oviparity (egg-laying) is ancestral. Viviparity (live birth) has apparently evolved at least twice in the chameleons, once in Bradypodion and again in members of the Trioceros bitaeniatus clade. Viviparous species tend to be medium-sized as a result of convergence from either small-sized ancestors or large-sized ancestors, respectively. Also viviparous species do not differ from oviparous species in clutch size, hatchling size, or the trade-off between clutch and hatchling size. The authors found that the basal chameleons (Brookesia, Rhampholeon and Rieppeleon) are small-sized and have developmental rates comparable with those of other lizards. However, the more derived chameleons (Calumma, Chamaeleo, Trioceros and Furcifer) are mostly large and all have relatively slow developmental rates. Some of the derived chameleon clades also exhibit developmental arrest (the embryo goes into stasis) and incubation periods may be extended to 6–10 months or more. Developmental arrest is apparently an adaptation to dry, highly seasonal climates where the time period favorable for oviposition and hatching is short. Long incubation periods thus ensure that hatching occurs when temperatures, rainfall, and food availability are appropriate for the young.

Literature
Andrews, R. M. and K. B. Karsten. 2010. Evolutionary innovations of squamate reproductive and developmental biology in the family Chamaeleonidae. Biological Journal of the Linnean Society, 100: 656–668. doi: 10.1111/j.1095-8312.2010.01442.x

Boistel, R., A. Herrel, G. Daghfous, P.-A. Libourel, E. Boller, P. Tafforeau, and V. Bels. 2010. Assisted walking in Malagasy dwarf chamaeleons. Biology Letters 2010 : rsbl.2010.0322v1-rsbl20100322.

Rakotondravony, D., A. Raselimanana, J. Ratsimbazaf, J. S. Sparks, L. Wilmé and J. U. Ganzhorn. 2010. Patterns of species change in anthropogenically disturbed forests of Madagascar. Biological Conservation 143:2351-2362.

Randrianantoandro, C., B. Razafimahatratra, M. Soazandry, J. Ratsimbazafy, R. K. B. Jenkins. 2010. Habitat use by chameleons in a deciduous forest in western Madagascar. Amphibia -Reptilia 31:27-35.


Monday, November 15, 2010

Hamadryad Research


 A number of recent papers have expanded our knowledge of the King Cobra, or Hamadryad, (Ophiophagus hannah), here a few that have appeared during 2010.

Bashir, et al. (2010) reports the sighting of the King Cobra from Yuksam village (27022’12.5’’N and 88013’27.0’’E). The village borders the Khangchendzonga Biosphere Reserve in the West District of Sikkim, India. The snake was observed in a drain adjoining human settlement (at an altitude of 1820 m) on 6 December 2009 at 0805 hr. The snake was estimated to be about 3−3.5 m. A few days later, the snake was seen basking on a rock near bamboo thickets adjoining the lake. There are two highlights: the new altitude record of 1840 m. for the northeast portion of the range; and, the fact that the snake was using the transitional forest between subtropical broadleaved evergreen forest and temperate forests. The species has not been previously reported from this Sikkim environment. Previously it was reported from Gangtok at 1700m in 1923 and was believed to be limited to the tropical forests of Sikkim Himalaya which are found below 1250 m. The highest known altitude record for the Hamadryad in northeastern India was 1700m at Khonoma, Nagaland (Das et al. 2008). 

Superimposition of haditoxin subunit A (blue) with erabutoxin-a (magenta), erabutoxin-b (cyan), and toxin-α (green), which highlights haditoxin's three-finger protein fold and its resemblance to other short-chain α-neurotoxins.
Chen and Lai (2010) from the Guangzhou University of Chinese Medicine sequenced the complete mitochondrial genome of King Cobra (GenBank accession number: EU_921899) by Ex Taq-PCR, TA-cloning and primer-walking methods. The cobra’s genome is similar to other vertebrate. It is 17 267 bp in length and encodes 38 genes (including 13 protein-coding, 2 ribosomal RNA and 23 transfer RNA genes) and it contains two, long, non-coding regions. This data demonstrated that Elapidae is more closely related to Colubridae (=Colubroidae) than Viperidae, supporting previous work.

Zedoary (Curcuma zedoaria, family Zingiberaceae) is a plant native to South and Southeast Asia and it was introduced into Europe sometime in the sixth century, and while it is used as a spice it is rare, having been replaced by ginger. It is commonly used in the northeastern Thailand as a snakebite remedy. Lattmann, et al. (2010) isolated the active compound from the rhizome of C. zedoaroides, determined its structure and assessed its antagonistic properties against King Cobra venom. The acetone extract from the rhizomes of Curcuma rhizomes contained a C20 dialdehyde, as the major component. The isolated curcuma dialdehyde was to be found active in both in vitro and in vivo tests for antivenin activity against King Cobra venom. Using isolated rat phrenic nerve-hemidiaphragm preparations, the researchers found a significant antagonistic effect on the inhibition of neuromuscular transmission and muscle contractions were inhibited by the venom, and found they could reversed it with Curcuma dialdehyde in organ bath preparations over a period of 2 hours. Mice injected with 0.75 mg/kg venom and the dialdehyde had a significantly increased survival time. Injection of the Curcuma dialdehyde 30 minutes before the subcutaneous injection of the venom resulted in a 100% survival time after 2 h compared with 0% for the control group. Thus the in vitro and in vivo evaluation confirmed the medicinal use of Zedoary against King Cobra venom. 

Roy et al. (2010) have described haditoxin, a novel peptide from the venom of Ophiophagus. They provide a detailed structural and functional characterization of this unusual neurotoxin. Using a 1.5 Å crystal structure, they found haditoxin exists as a homodimer, similar to the κ-neurotoxin family, but the monomeric subunits of haditoxin, consist of a three-finger protein fold closely resembling a short-chain α-neurotoxins, unlike κ-neurotoxin monomers, which resemble long-chain α-neurotoxins. While haditoxin could antagonize several classes of nicotinic acetylcholine receptors in neurons and muscle, its greatest potency was against receptors, which neiher recognized by short-chain α-neurotoxins or κ-neurotoxins. Thus haditoxin might have many future uses in developing molecular probes and therapeutic agents.

Literature
Bashir, T., K. Poudyal, T. Bhattacharya, S. Sathyakumar & J.B. Subba, 2010. Sighting of King Cobra Ophiophagus hannah in Sikkim, India: a new altitude record for the northeast. Journal of Threatened Taxa 2(6): 990-991.
 
Chen N. and X. P. Lai. 2010. [Sequencing and analysis of the complete mitochondrial genome of the King Cobra, Ophiophagus hannah (Serpents: Elapidae)] [Article in Chinese]. Yi Chan 32(7):719-25.

Lattmann, E., J. Sattayasai,, N. Sattayasai, A. Staaf, S. Phimmasone, C. H. Schwalbe, and A. Chaveerach. 2010. In-vitro and in-vivo antivenin activity of 2-[2-(5,5,8a-trimethyl-2-methylene-decahydro-naphthalen-1-yl)-ethylidene]-succinaldehyde against Ophiophagus hannah venom. Journal of Pharmacy and Pharmacology, 62:257–262. doi: 10.1211/jpp.62.02.0014

Roy, A., X. Zhou, M. Z. Chong, D. D'hoedt, C. S. Foo, N. Rajagopalan, S. Nirthanan, D. Bertrand, J. Sivaraman, and R. Manjunatha Kini. 2010. Structural and Functional Characterization of a Novel Homodimeric Three-finger Neurotoxin from the Venom of Ophiophagus hannah (King Cobra) Journal of Biological Chemistry 285: 8302-8315.







Sunday, November 14, 2010

What Are Turtles?


Odontochelys semitestacea
Students are often very surprised to look at a turtle shell and discover that it has ribs fused to the shell. And, more than one have asked, “is this why turtles can crawl out of their shells, like they do in cartoons?” Turtle shells are novel structures, and turtles, themselves are novel vertebrates that have created controversies and interesting speculations as to what they are related to. Three hypotheses  are available: (1) turtles are the sister to the crocodilians – turtles and crocs have long been called shield reptiles, because both have substantial dermal armor; (2) turtles are the sister to lizards and tuataras; and (3) turtles are the sister to the diapsid reptiles [Araeoscelidia, Avicephala, Hupehsuchia, Thalattosauria, Younginiformes, Ichthyopterygia (ichthyosaurs); Lepidosauromorpha; and the Archosauromorpha] in other words animals most people consider living reptiles, plus many extinct forms of reptiles including the dinosaurs and birds.

Fossil turtles are known from the Triassic, and perhaps the most spectacular find was in 2008. The oldest turtle lived about 220 million years ago in what is now southwestern China. It had a mouth full of small, peg-like teeth, and it had it only the bottom half a shell. The remains were described and named Odontochelys semitestacea by Chun Li, of the Chinese Academy of Sciences. Odontochelys was a small about 35 cm, and its shell consisted of only a plastron. Li' and colleagues suggest that Odontochelys' incomplete shell represents an intermediate step along the evolutionary path to living turtles.
Artist reconstruction of Odontochelys semitestacea. 
This month, Tyler Lyson of Yale University and colleagues, have published the results of a re-analysis of a morphological data set that suggested turtles are the sister to the lizard-tuatara clade. They added two extinct species (Proganochelys and Eunotosaurus) that have been long suspected to be close turtle relatives, and did not make any other changes to the data set. They point out that various anatomy supports all three of the hypotheses. The results of Lyson et al. place turtles outside of Diapsida, a finding that is contrary to most recent molecular work. They note that molecular studies suggest a turtle + archosaur relationship, but that there is little morphological evidence to support this clade. Another study that combined morphological and molecular data also concluded that turtles are outside Diapsida, agreeing with the Lyson results.
The very old fossils, and the unique morphology suggest turtles are in fact quite distinct from any living animals currently considered reptiles. Thus, do turtles belong in their own class of vertebrates? 


 
The original caption from Lyson et al.  “The position of turtles based on molecular (1: e.g. Hugall et al. 2007) and morphological datasets (2: e.g. deBraga & Rieppel 1997; 3: Gauthier et al. 1988). The addition of key fossils eliminates the apparent disagreement among morphological datasets in support of turtles outside Diapsida (3). The Permian ‘parareptile’ Eunotosaurus shares uniquely derived features with turtles that help fill important gaps in the evolutionary origin of the turtle shell. Bootstrap (top) and Bremer (bottom) support values are provided for the Eunotosaurus-turtle clade. Star indicates complete shell.”

Literature
Chun Li, Xiao-Chun Wu, Olivier Rieppel, Li-Ting Wang, Li-Jun Zhao. 2008. An ancestral turtle from the Late Triassic of southwestern China. Nature, 456: 497-501 DOI: 10.1038/nature07533





Friday, November 12, 2010

Cape Town Still Supports A Population of Hemachatus haemachatus


Abbé Pierre Joseph Bonnaterre described the Rinkhals also called the Ringhals or Ring-necked Spitting Cobra as Coluber haemachatus in 1790 in his Tableau encyclopedia.... Today the snake is known to herpetologists as Hemachatus haemachatus. The Rinkhal is widely distributed, being known from known from the Southern Cape Province of South Africa, northeast through the Free State, Lesotho, Transkei, Kwazulu Natal, South Africa, Western Swaziland and parts of Gauteng, South Africa. And, there is apparently an isolated population near Inyanga on the Zimbabwe - Mozambique border. The City of Cape Town asked the public to report any Rinkhals sightings that they may have made in the past decade, in order to assist the biodiversity management branch in their research into this species.  At least some thought Hemachatus haemachatus to be extinct in the Cape Town area. But the public’s response to the request suggests there is a population still living within their metropolitan boundaries. The cobra has been reported from Somerset West and Gordon's Bay, from the Cape Peninsula, and around Table Mountain National Park, and north along the West Coast towards Mamre.  While the description s of the snake in these areas suggests it is present, they have yet to be confirmed. The News Times of Cape Town is reporting that citizens are delighted that the snake is still present.

Roger Repp's Long-term Field Study of WDRs


Roger Repp has sent the following account of his recent field work on a Crotalus atrox, a field study that has been going on for 9.5 years.  Previous reports have been emailed to a smaller group of herpers.

Howdy Herpers,

We just finished the most exciting week ever in our 9.5 year study. Some may remember that the last report ended with a picture of a concerned mother atrox (CRAT #124, "Beverly") coming out of her nest hole to ward off an interloper. For review's sake, we include that pic again. The next three images (Figure 1) are further developments at the nest hole, culminating with five neo shed skins being collected on 15 September.

The next three pics (Figure2 ) are of a pre-courtship and eventual hook up of an unknown male atrox with CRAT #124, "The Princess." The photo of the male appearing to hide his head is misleading. He is actually trying to squeeze down a small soil hole to get to the Princess. This occurred on 11 September.  That evening, John Slone, Marty Feldner and I noted that this snake had forced his entrance to the point where the tip of his rattle was flush with the soil edge. I CAN'T BELIEVE THAT NONE OF US TOOK A PHOTO OF THAT! Anyhow, the next two pics in the sequence, taken  15 September, show that perseverance pays off. I do believe that I could be arrested for one of these photos.

Lastly, on 19 September, Ryan Sawby, The Peach, and I had tracked down our last snake. It was CRAT #121, "Tracy." She was buried in a root system that was covered by wash jetsum, not visible. While I was starting the write up, The Peach and Ryan wandered off, merrily admiring the explosive insect life that was occurring all around us. It was HOT! HOT! HOT!, and I was right in the sun, tucked against a heat-sinking embankment. I finally realized that I was doing this write up alone, so I had to drag all the junk out
of my pack in order to do the job that The Peach normally does.

All of a sudden, there's all this shouting. "ROGER, ATROX COMBATTING! GET OVER HERE WITH YOUR CAMERA. WHAT ARE YOU DOING? ROGER, DID YOU HEAR ME? ROGER, COMBAT! ROGER? ROGER! (Figure 3)

I must have been over there within ten seconds of the commotion, but my two comrades later drilled me good for not hopping to it quickly enough. The next five shots are part of what I got with the camera. The fight was between an old guy and a young stud. My first impression was that the young stud was winning, but that is not what the photos show. I'm glad to say that I think the old guy was winning. The last photo shows the young stud holding his ground. The old guy came after us, changed his mind, and started to flee the scene.

The Peach insisted that we process the snakes, but the young stud gave us the slip. The poor old guy took the brunt of the punishment in this battle. He turned out to be CRAT #40, first processed in March of 2003. We have encountered him several times before.

The Peach's suggestion that we finish the write up on "Tracy" was met with stiff resistance. The bitching and moaning on the scribe's part was legendary. But thank goodness, the scribe listened to reason. It was REALLY hot!

We can't prove it, but it is likely that "Tracy" was the cause of the fight. She is in the hackberry roughly 3 meters to the left of the first two photos.

There were also many other great events that happened this past week. Hopefully, I can get out another report soon. For now, Yehaw! Life is good.

This here is roger repp signing off from sunny and HOT Southern Arizona, where the snakes are strong, the lizards are handsome, and the turtles are barely average.

Atlantic Leatherback Migration & Dives


The critically endangered Leatherback Sea Turtle, Dermochelys coriacea, occurs in all of the ocean basins and makes the longest migrations of any sea turtle. The Leatherbacks travels involve foraging for jellyfish which are patchily-distributed as well as reproduction. Sabrina Fossette of the Universite´ de Strasbourg, and colleagues have just published the results of a study combining data from 16 individuals from different populations. They attempted to understand intra- and inter-population variability and take it into account in the implementation of conservation strategies of this critically endangered species. They investigated the movements and diving behavior of 16 Atlantic Leatherback turtles from three different nesting sites and one foraging site during their post-breeding migration to examine the variability in migratory patterns.

The team used satellite-derived behavioral and oceanographic data and showed that turtles used Temporary Residence Areas (TRAs) scattered throughout the Atlantic Ocean. Nine were in the neritic (coastal waters less than 200 m in depth) domain and 13 in the oceanic domain. These TRAs were associated with large scale surface oceanographic features of different types (i.e., altimetric features and/or surface chlorophyll a concentration). Turtles also exhibited relatively similar horizontal and vertical behaviors when in TRAs, such as slow swimming velocities, a sinuous path, and shallow dives, indicative of foraging activity in these food rich regions. The migratory paths and TRAs distribution showed interesting similarities with the trajectories of passive satellite-tracked drifters, suggesting that the general dispersion pattern of adults from the nesting sites may reflect the passive dispersion initially experienced by hatchlings.

One female turtle was tracked for 632 days and moved a total of 17,614 km (about 10,700 miles), suggesting she was averaging about 28 km or 28 miles per day. Behavioral variability of these turtles may be linked with the initial hatchling drift scenarios and be greatly influenced by environmental conditions. This high degree of behavioral plasticity in Atlantic Leatherback turtles makes species-targeted conservation strategies challenging and stresses the need for a larger dataset (>100 individuals) for providing general recommendations in terms of conservation.

The team observed shallow dives at all TRAs at all latitudes. Oceanic TRAs dives were longer (20 min) than in neritic TRA dives and were concentrated in the epipelagic layer (50–80 m). Fossette et al. suggest that the diving behavior was shaped by local prey distribution and density. Periods of very short shallow dives and high use of surface waters were previously reported for foraging Leatherbacks at high latitude where gelatinous plankton is available at shallow depths. 

Below is a map showing the movements of the turtles in this study, with the original caption.

Reconstructed movements of 16 Argos-tracked leatherback turtles during their migration in the Atlantic Ocean from 2005 to 2008. Twelve SRDLs were deployed on gravid females nesting in Panama (n = 3, PAyear-ID), Suriname and French Guiana complex (n = 6, SUyear-ID and FGyear-ID, respectively), and Gabon (n = 3, GAyear-ID). Four others were deployed on leatherback turtles incidentally captured by Uruguayan fisheries (pelagic longlines and coastal bottom-set gillnets) in international waters of the Southwest Atlantic and in Kiyú, Uruguay, respectively (URyear-ID). For each turtle, transit and Temporary Residence Areas (TRAs) are identified by dotted and solid lines, respectively. Each TRA is identified by a number in black and white, for neritic and oceanic domains, respectively

Thursday, November 11, 2010

The Caló den Rafelino Viper


The Blunt-nosed Viper, Macroviper lebetina.
The Oriental Viper complex contains the Desert Viper (Macroviper deserti) from North Africa. The Blunt-nosed Viper (Macroviper lebetina) a widespread North Africa-Middle Eastern species; the Moorish Viper (Macroviper mauritanica), from northwest Africa; the Milos Viper (Macroviper schweitzeri) from the Cyclades Archipelago in the Aegean Sea, as well as Milos Island and its satellites; and probably the Palestine Viper (Macroviper or Viper palestinae) from Israel, Syria, Jordan, and Lebanon; and several fossil forms. Nilson and Andrén (1997) also included the Russel's Vipers (Daboia) in this clade. These snakes tend to be found at low elevations and low latitudes, and prefer hot, dry climates, and they lay eggs (unlike other European and Middle Eastern Vipera). Now, Bailon et al. report the first fossil record of Oriental vipers from the Pliocene of the western Mediterranean.   Two large-sized vertebrae were found in karst deposits on the eastern coast of Mallorca, close to Caló den Rafelino. The centrum length of the trunk vertebra (12.7 mm) represents the largest known specimen of the Oriental viper complex and it suggests a species that reached a body length of about 200 cm. The authors hypothesize that this snake reached Mallorca in the Miocene (5.6-5.32 MYA) during the Messinian Salinity Crisis. At this time sea level dropped about 1500 m establishing a connection between the mainland and the Balearic Islands. Favorable ecological conditions for these snakes most likely existed at this time, including a warm-temperate climate and a relatively dry, open landscape. The authors suggest that because of its large body size; the Caló den Rafelino Viper can be considered one of the largest predators in Mallorca during the Early Pliocene.

Literature
Bailon, S., P. Bover, J. Quintana and J. A. Alcover. 2010.First fossil record of Vipera Laurenti 1768 “Oriental vipers complex” (Serpentes: Viperidae) from the Early Pliocene of the western Mediterranean islands. Comptes Rendus Palevol, 9:147-154.

Nilson, G., and C. Andrén.  1997. Evolution, systematics and biogeography of Paleartic vipers, In: R.S. Thorpe, W. Wüster, A. Malhotra (Eds.), Venomous snakes: ecology, evolution and nakebite. Symposium of the  Zoological Society of London 70:31–42.