Monday, October 29, 2012

First feathered dinosaurs from NA

This is an artistic reconstruction of feathered ornithomimid dinosaurs
 found in Alberta. Credit: Julius Csotonyi.
The ostrich-like dinosaurs in the original Jurassic Park movie were portrayed as a herd of scaly, fleet-footed animals being chased by a ferocious Tyrannosaurus rex. New research published in the journal Science reveals this depiction of these bird-mimic dinosaurs is not entirely accurate -- the ornithomimids, as they are scientifically known, should have had feathers and wings.

The new study, led by paleontologists Darla Zelenitsky from the University of Calgary and François Therrien from the Royal Tyrrell Museum of Palaeontology, describes the first ornithomimid specimens preserved with feathers, recovered from 75 million-year-old rocks in the badlands of Alberta, Canada.

"This is a really exciting discovery as it represents the first feathered dinosaur specimens found in the Western Hemisphere," says Zelenitsky, assistant professor at the University of Calgary and lead author of the study. "Furthermore, despite the many ornithomimid skeletons known, these specimens are also the first to reveal that ornithomimids were covered in feathers, like several other groups of theropod dinosaurs."

The researchers found evidence of feathers preserved with a juvenile and two adults skeletons of Ornithomimus, a dinosaur that belongs to the group known as ornithomimids. This discovery suggests that all ornithomimid dinosaurs would have had feathers.

The specimens reveal an interesting pattern of change in feathery plumage during the life of Ornithomimus. "This dinosaur was covered in down-like feathers throughout life, but only older individuals developed larger feathers on the arms, forming wing-like structures," says Zelenitsky. "This pattern differs from that seen in birds, where the wings generally develop very young, soon after hatching."

This discovery of early wings in dinosaurs too big to fly indicates the initial use of these structures was not for flight.

"The fact that wing-like forelimbs developed in more mature individuals suggests they were used only later in life, perhaps associated with reproductive behaviors like display or egg brooding," says Therrien, curator at the Royal Tyrrell Museum and co-author of the study.

Until now feathered dinosaur skeletons had been recovered almost exclusively from fine-grained rocks in China and Germany. "It was previously thought that feathered dinosaurs could only fossilize in muddy sediment deposited in quiet waters, such as the bottom of lakes and lagoons," says Therrien. "But the discovery of these ornithomimids in sandstone shows that feathered dinosaurs can also be preserved in rocks deposited by ancient flowing rivers."

Because sandstone is the type of rock that most commonly preserves dinosaur skeletons, the Canadian discoveries reveal great new potential for the recovery of feathered dinosaurs worldwide.

The fossils will be on display this fall at the Royal Tyrrell Museum in Drumheller, Alberta.

Citation
D. K. Zelenitsky, F. Therrien, G. M. Erickson, C. L. DeBuhr, Y. Kobayashi, D. A. Eberth, F. Hadfield. Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins. 2012. Science, 338 (6106): 510 DOI: 10.1126/science.1225376

New squamate phylogeny

Epictia tenella. JCM
A new study, published online in Biology Letters on Sept. 19, has utilized a massive molecular dataset (161 squamate species for up to 44 nuclear genes each and 33 717 base pairs), the largest genetic datasets assembled for reptiles.to reconstruct the evolutionary history of lizards and snakes. The results reveal a surprising finding about the evolution of snakes: that most snakes we see living on the surface today arose from ancestors that lived underground.

The article, entitled "Resolving the phylogeny of lizards and snakes (Squamata) with extensive sampling of genes and species," describes research led by John J. Wiens, an Associate Professor in the Department of Ecology and Evolution at Stony Brook University.

In contrast to most other recent studies, the authors found that dibamids and gekkotans are together the sister group to all other squamates. The results also show that almost all groups of snakes arose from within a bizarre group of burrowing blind snakes called scolecophidians. This finding implies that snakes ancestrally lived underground, and that the thousands of snake species living today on the surface evolved from these subterranean ancestors. Remarkably, they found the distinctive scolecophidians (blind snakes) are paraphyletic with respect to other snakes, suggesting that snakes were primitively burrowers and subsequently re-invaded surface habitats.

The authors suggest that there are still traces of this subterranean ancestry in the anatomy of surface-dwelling snakes. "For example, no matter where they live, snakes have an elongate body and a relatively short tail, and outside of snakes, this body shape is only found in lizards that live underground," said Professor Wiens. "Snakes have kept this same basic body shape as they have evolved to invade nearly every habitat on the planet -- from rainforest canopies to deserts and even the oceans."

Citation
J. J. Wiens, C. R. Hutter, D. G. Mulcahy, B. P. Noonan, T. M. Townsend, J. W. Sites, T. W. Reeder. Resolving the phylogeny of lizards and snakes (Squamata) with extensive sampling of genes and species. 2012. Biology Letters, 2012; DOI: 10.1098/rsbl.2012.0703

Road-killed Herps in Protected Areas


Photo credit::Núria Garriga
Amphibians are the vertebrate group that is more likely to become roadkill in Catalonia, even more so than reptiles, mammals and birds. This is the case according to an international team of scientists who have concluded that highly protected areas are home to more cases of animal death on the roads.

Our network of roads is considered one of the main threats to fauna survival. Researchers at the universities of Barcelona (UB), Porto (Portugal) and Uppsala (Sweden) have studied the number of vertebrate deaths on 820 kilometres of road in North Eastern area of Spain and Portugal.

"The project consisted of analysing the impact of the road network on fauna, leading to numerous studies across the whole of Catalonia to record all specimens of roadkill found," as explained by Núria Garriga, researcher at the UB and lead author of the study headed by Gustavo A. Llorente, a scientist at the same university.

Field work was published in the 'Biodiversity and Conservation' journal and was carried out over four years on 41 secondary roads in Catalonia. Some 20 km of each road were inspected during summer and autumn. As Garriga points out, "there are few studies on an international level that have carried out such an extensive research and sampling."

Nature reserves like Parc Natural dels Aiguamolls de l'Empordà, Parc del Garraf, Parc Natural de la Zona Volcànica de la Garrotxa, Parc Natural de Sant Llorenç del Munti l'Obac and Parc Natural del Montseny.

"We got in a slow moving car to collect data. When we spotted a dead animal we would stop, make a record and note down the species. We also took down other significant information like surrounding vegetation and the closest water points," outlines the researcher.

One of the main conclusions of the study was that amphibians are more likely to become roadkill and that roads within nature reserves and natural parks are home to the highest number of animal road deaths.

"This could be explained by the fact that protected areas frequently receive a high number of visitors, which in turn increases the flow of traffic in places that are teaming with wild life," ensures the researcher.

According to the experts, to decrease amphibian death we would have to build special passages for them in high-risk areas. These come in the form of tunnels under the road designed to allow the passage of animals.

The team is currently working to identify hotspots. They therefore inspected seven roads throughout an entire year to define the most dangerous areas and protect them.

Citation
Núria Garriga, Xavier Santos, Albert Montori, Alex Richter-Boix, Marc Franch, Gustavo A. Llorente. Are protected areas truly protected? The impact of road traffic on vertebrate fauna. Biodiversity and Conservation, 2012; 21 (11): 2761 DOI: 10.1007/s10531-012-0332-0

Thursday, October 25, 2012

Frog eggs & climate change

Pantless tree frog embryos within the eggs on a leaf surface.
The embryos die within a day if there is no rain to moisten
the egg mass. Photo credit Justin Touchon.
Most of the more than 6,000 species of frogs in the world lay their eggs in water. But many tropical frogs lay their eggs out of water. This behavior protects the eggs from aquatic predators, such as fish and tadpoles, but also increases their risk of drying out. Justin Touchon, post-doctoral fellow at the Smithsonian Tropical Research Institute, discovered that climate change in Panama may be altering frogs' course of evolution.

By analyzing long-term rainfall data collected by the Panama Canal Authority, Touchon discovered that rainfall patterns are changing just as climate-change models predict.

"Over the past four decades, rainfall has become more sporadic during the wet season," said Touchon. "The number of rainy days decreased, and the number of gaps between storms increased."

The eggs of the pantless treefrog, Dendropsophus ebraccatus, are extremely susceptible to drying. The embryos die within a day when there is no rain. Heavy rains trigger breeding, so as storms become sporadic, the chance of rain within a day of being laid decrease and so does egg survival.

As weather patterns have changed, the advantage of laying eggs out of water has decreased, not only for pantless treefrogs but potentially for many species. "Pantless treefrogs can switch between laying eggs in water or on leaves, so they may weather the changes we are seeing in rainfall better than other species that have lost the ability to lay eggs in water," said Touchon. "Being flexible in where they put their eggs gives them more options and allows them to make decisions in a given habitat that will increase the survival of their offspring."

Citation
Touchon J.C. A treefrog with reproductive mode plasticity reveals a changing balance of selection for non-aquatic egg-laying. The American Naturalist, 2012; DOI: 10.5061/dryad.8j1hb

A new egg-eating sea snake in the genus Apiysurus


A new species of egg-eating sea snake, Aipysurus mosaicus from northern Australia and southern New Guinea has been described by Sanders et al (2012). A. mosaicus was previously considered an allopatric population of A. eydouxii, which occurs throughout the Sunda Shelf and in New Guinea. Molecular analyses reveal these two species to be sister lineages with a deep phylogenetic divergence exceeding that of all other sampled species pairs in Aipysurus. Aipysurus mosaicus is also distinguished from A.eydouxii by morphological characters: number of ventral scales, color pattern (e.g. number and shape of transverse body bands), internal soft anatomy (e.g. position of heart in relation to ventral scales), and skeletal morphology (e.g. shape of nasal and caudal neural spines). Additional sampling is needed to clarify the extent of geographic contact between A. eydouxii and the new species in New Guinea where they appear to be sympatric.

The new sea snake was found by chance by two research colleagues, Johan Elmberg of Sweden and Arne Rasmussen of Denmark, when they were examining formalin-filled jars of snakes at the Natural History Museum in Copenhagen. They found two sea snakes with the same name on the label, which had been there since being sent to Denmark by collectors in the 1800s. "But they looked different and didn't seem to belong to the same group of snakes," Johan Elmberg said in the statement from Kristianstad University in southern Sweden. "After comparing the sea snakes with other similar species in other museums in Europe it was even more obvious that we had found a new distinct sea snake," he said. The Mosaic sea snake is named after its unusually patterned skin, which looks like a Roman floor mosaic. It "never goes ashore and now that its identity is known it is apparent that it is relatively common in the sea in northern Australia and southern New Guinea," Elmberg said. He said the presence of sea snakes was a good sign. "Sea snakes are a good indicator of how the coral reefs and other precious ecosystems are doing. If there are snakes left in the environment it shows that the reefs are healthy and intact," he explained. Unlike some other sea snakes which have strong venom, the Mosaic sea snake is "virtually harmless," Elmberg said, adding that the species is unusual in that it feeds on fish eggs, and therefore has only very small fangs.

Citation
Kate L. Sanders et al. 2012. Aipysurus mosaicus, a new species of egg-eating sea snake (Elapidae: Hydrophiinae), with a redescription of Aipysurus eydouxii (Gray, 1849). Zootaxa 3431: 1–18.

Wednesday, October 24, 2012

Iguana iguana genetically divided

Recent molecular and morphological investigations of widespread species have demonstrated that many of them show deep genetic divergences and morphology that is geographically concordant.In many instances this results in the recognition of cryptic species. In an early on-line view of an article to be published in the Journal of Biogeography, Catherine Stephen and colleague investigated the genetic structure of the Neotropical common green iguanas (Iguana iguana) and compare that structure with past geological events and present barriers to gene flow. Additionally, they compare levels of divergence between lineages within Iguana with closely related genera in the subfamily Iguaninae.

The authors collected DNA sequences at four loci for up to 81 individuals from 35 localities in 21 countries. The four loci, one mitochondrial (ND4) and three nuclear (PAC, NT3, c-mos), were chosen for their differences in coalescent and mutation rates. Each locus was analyzed separately to generate gene trees, and in combination in a species-level analysis.

The pairwise divergence between Iguana delicatissima and I. iguana was much greater than that between sister species of Conolophus and Cyclura and non-sister species of Sauromalus, at both mitochondrial (mean 10.5% vs. 1.5–4%, respectively) and nuclear loci (mean 1% vs. 0–0.18%, respectively). Furthermore, divergences within I. iguana were equal to or greater than those for interspecific comparisons within the outgroup genera. Phylogenetic analyses yielded four strongly supported, geographically defined mitochondrial clades (3.8–5% divergence) within I. iguana. Three of the four clades were found using PAC (0.18–1.65% divergence) and two using NT3 (0.6% divergence) alone. The primary divergence, recovered in three polymorphic loci, was between individuals north and south of the Isthmus of Panama. The southern group was differentiated into clades comprising individuals on either side of the northern Andes, using both PACand ND4.

Deep genetic divergences were found within I. iguana that are congruent with past and current geological barriers. These divisions are greater than sister species comparisons in other Iguaninae genera, indicating the possible presence of cryptic species. Geological changes from the mid-Miocene through the Plio-Pleistocene have shaped the pattern of divergence in I. iguana. The uplift of the northern Andes presented a barrier between South American I.iguana populations by 4 Ma. Populations north of the Isthmus of Panama form a clade that is distinct from those to the south, and may have expanded northwards following the closing of the Isthmus of Panama 2.5 Ma.

Citation
Stephen, C. L., Reynoso, V. H., Collett, W. S., Hasbun, C. R., Breinholt, J. W. (2012) Geographical structure and cryptic lineages within common green iguanas, Iguana iguana. Journal of Biogeography. doi: 10.1111/j.1365-2699.2012.02780.x

Tuesday, October 23, 2012

Bushmeat & Local Human Diets

Malaysian Snail-eating Turtles on the grill in Thailand. JCM
Oct. 23, 2012 - Animals like antelope, frogs and rodents may be tricky to catch, but they provide protein in places where traditional livestock are scarce. According to the authors of a new paper in Animal Frontiers, meat from wild animals is increasingly important in central Africa.

“The elephant or hippopotamus may provide food for an entire community, smaller antelope may feed a family, while a rat or lizard may quell the hunger of an individual. Alternatively, these species are often sold on the road side or at local markets to supply a much needed source of cash revenue,” write researchers Louw Hoffman and Donna Cawthorn.

Hoffman and Cawthorn are interested in the nutritional value of wild animals. They cite previous studies showing that bushmeat contributes 20 to 90 percent of the animal protein eaten in many areas of Africa. Studies show that some bushmeat species are high in protein, amino acids, vitamins and minerals.

“Besides the contribution of protein, the provision of calories from bushmeat cannot be overlooked and while the meat of many wild animals is low in fat, some species such as rats and porcupines are prized for their fatty consistencies,” write Hoffman and Cawthorn.

Nutrients from wild animals help people survive in these regions. According to the U.N. Food and Agriculture Organisation, 25 percent of the world’s undernourished people live in sub-Saharan Africa.

But with increased consumption comes a loss of biodiversity. Hoffman and Cawthorn cite the decline of primates in central Africa and the over-hunting of the manatee and pigmy hippopotamus in Ghana.

“This situation is exacerbated by the fact that international and domestic commercial and often illegal trade in bushmeat and other parts of wild animals is increasing and is largely outpacing legitimate subsistence hunting,” write Hoffman and Cawthorn.

An alternative is the “semi-domestication” of certain animals. Already, many African antelope are raised in large enclosures or in state-owned nature preserves, though that meat is often sold for export. Hoffman and Cawthorn write that rodents could easily be raised as food animals because of their quick rates of reproduction and simple care requirements.

“Besides supplying valuable protein, the meat of rodents also contains essential amino acids which are required in the human diet,” they write.

In their paper, Hoffman and Cawthorn also examine the importance of wildlife outside of Africa. They write about the consumption species like guinea pigs in South America, alligators in the United States and snakes in Asia.

“Today, up to 4,000 tons of snake meat are served annually in China, where this reptile’s meat is commonly served in restaurants in cities such as Shanghai, Foshan, and Yangshuo,” they write.

Hoffman, L.C. and Cawthorn, D.-M. 2012. What is the role and contribution of meat from wildlife in providing high quality protein for consumption. Animal Frontiers 2:40-53.

Monday, October 22, 2012

Western diamondback rattlesnake females not anorexic during pregnancy

A southern Arizona Crotalus atrox at its den. JCM

Anorexia (cessation of feeding) is frequently associated with gestation in snakes. Several hypotheses have been proposed to explain this, most often it is obstruction of the digestive tract due to the presence of fetuses or eggs, i.e. the increase in eggs and embryos take up so much room that the female cannot get food through her gut. Using radiotelemetry, Schuett et al. (2012)  investigated the feeding and spatial ecology of a live-bearing viperid snake, the western diamond-backed rattlesnakes (Crotalus atrox). From 2001 to 2010, we determined the feeding frequency and home range size of 27 adult females during their active season (March–October) in the Sonoran Desert of Arizona. The authors addressed a central hypothesis: do
hunting and feeding occur throughout pregnancy? They also tested a corollary hypothesis: does pregnancy influence home range size? Other viperid snakes (including some rattlesnakes) have been show to greatly reduce their home range during pregnancy.

Hunting and feeding were documented from March to October and during pregnancy (June to mid-September). They found feeding frequency was significantly greater in late pregnancy, a result that is in sharp contrast to most other large-bodied vipers. Furthermore, home range sizes in gestating subjects did not differ from those in non-reproductive years. Births occurred from mid-August to mid-September and mean litter size was 3.4. Frequent feeding in C. atrox during gestation unquestionably provides energy and nutrients to the mother, which is likely important for survival, but such food consumption does not imply that nutrients are used by the fetuses. There is, however, recent evidence in other snakes, including a pitviper, that amino acids are transferred to fetuses. Feeding during pregnancy in C. atrox may be important for both income and capital mode reproduction. Hunting and feeding throughout gestation might be accomplished by having relatively small litters not burdened by a body cavity filled with fetuses. Thus, reduction in litter size may thus be a life-history (fecundity) trade-off that permits females to survive and maintain pregnancy in regions where drought and high temperatures are often extreme and chronic.

This paper is available in an early on-line view before publication.


Citation
Schuett, G. W., Repp, R. A., Amarello, M., Smith, C. F. (2012), Unlike most vipers, female rattlesnakes (Crotalus atrox) continue to hunt and feed throughout pregnancy. Journal of Zoology. doi: 10.1111/j.1469-7998.2012.00969.x


Sunday, October 21, 2012

A ranid frog with a retractable spike in its fifth digit

The Otton Frog, Babina subaspera. Photo credit N. Iwai
Combat-ready spikes which shoot from fingers sounds like the weaponry of a comic book hero, but a Japanese scientist has found exactly this in a rare breed of frog. The discovery, which is published in the Journal of Zoology, reveals how the Otton frog uses spikes which protrude from a false thumb for both combat and mating.

The study, conducted by Dr Noriko Iwai from the University of Tokyo, focused on the Otton frog (Babina subaspera), whose habitat is the Amami islands of Southern Japan. Unlike most other frogs the Otton has an extra digit-like structure, a trait it shares with the five-fingered Hypsiboas rosenbergi frogs of Latin America.

"Why these 'fifth fingers' exist in some species remains an evolutionary mystery, but the extra digit of the Otton is in fact a pseudo-thumb," said Dr Iwai. "The digit encases a sharp spine which can project out of the skin, which fieldwork demonstrates is used for combat and mating."

Dr Iwai has studied the rare frogs since 2004 in order to understand the species' distribution, breeding habits and range; all factors which will contribute to any conservation strategy. Once she began exploring how the Ottons use their pseudo-thumbs Dr Iwai discovered that while both males and females had the spike, it was only used by males.

Males were found to have larger pseudo-thumbs than the females and Dr Iwai believes that the spikes evolved for anchoring to the female, known as amplexus, the Latin for embrace, during mating.

"While the pseudo-thumb may have evolved for mating, it is clear that they're now used for combat," said Dr Iwai. "The males demonstrated a jabbing response with the thumb when they were picked up, and the many scars on the male spines provided evidence of fighting."

The conditions on the Amami islands make combat, and the need for weaponry, a key factor for the frogs' mating success. Individuals fight over places to build nests, while the chances of a male finding a mate each night are rare, thus the ability to fight off competitors may be crucial.

Perhaps unfortunately, the comic book hero image is slightly dented by the frogs' fighting style. Rather than dueling with thumb spikes the males wrestle each other in an embrace, jabbing at each other with the spines. This fighting style helps confirm the theory that the spines were original used for embracing mates.

"More research is needed to look at how the pseudo-thumb evolved and how it came to be used for fighting," concluded Dr Iwai. "The thumbs use as a weapon, and the danger of the frogs harming themselves with it, makes the Otton pseudo-thumb an intriguing contribution to the study of hand morphology."


Iwai. N.2012 Morphology, function and evolution of the pseudothumb in the Otton frog. Journal of Zoology, 2012; DOI: 10.1111/j.1469-7998.2012.00971.x

Saturday, October 20, 2012

Color variation in island strawberry frogs


The strawberry poison frog Oophaga pumilio ranges from Nicaragua through western Panama and throughout most of its mainland range it has a reddish-orange body with blue-black legs, and small black spots on its dorsum. In the Bocas del Toro Archipelago of Panama the frog  displays a high level of  variation is its warning coloration. More than 15 color morphs are present in the archipelago and include yellow, red, blue, lime green, and bronze morphs as well as  others, and the different morphs may occur on the same island. Morphs with spots are also present in the Archipelago, with the size and number of spots varying on the specific morph. The degree of conspicuousness also varies among color morphs in the Bocas del Toro Archipelago. Hegna et al. (2012) used unspotted models of O. pumilio to determine if predation might help explain the color polytypism on Isla Colon in the Bocas del Toro Archipelago of Panama. The authors tested whether attack rates differed among the red mainland morph, green-yellow Isla Colon morph, and a brown colored control. They found that frog color significantly predicted being attacked. The local green Isla Colon models were attacked more than foreign red or brown models. No difference in attack rate were found between red and brown control models. Their results suggest that the red mainland morph possesses a more effective warning signal, even when it is not the local morph. Honest signaling of unpalatability, neophobia, and the use of search images by local predators are potential explanations. Similarity of the brown model to other local poison frogs might explain the lower attack rate compared to previous work. The attack rate was lower on Isla Colon compared to mainland Costa Rica, which supports the hypothesis that less predation in the Bocas del Toro Archipelago may contribute to the overall variation in warning colors in O. pumilio and there by relaxing selection for aposematic traits.

Citation
Hegna, R., Saporito, R., and Donnelly, M, 2012. Not all colors are equal: predation and color polytypism in the aposematic poison frog Oophaga pumilio.Evolutionary Ecology 1-15.Doi: 10.1007/s10682-012-9605-z

Friday, October 19, 2012

Lizards In Traditional Medicines in India

Gekko gecko in a Malaysian market. JCM

There are about 5729 lizard species in the world, and in many cultures saurians are believed to have medicinal properties and their skins are frequently used in the novelty leather industry. Subtamanean and Reddy (2012) discuss the use of the common monitor lizard and the Tokay gecko as examples of species frequently exploited by humans on the Indian subcontinent.  In India, products derived from Varanus bengalensis  are used to treat a variety of ailments, including hemorrhoids, rheumatism, body pain and burns, as well as spider and snake bites. It is also used as a cure for arthritis. The fat and meat of this lizard work like the hormone testosterone and hence these are considered a delicacy and an aphrodisiac in South India. The meat is also believed to be effective in curing the tension that sets into the muscles controlling breathing due to lack of oxygen. The powdered meat is capable of building up resistance and is believed to mitigate rise in blood sugar. It is used in energy tonics for blood and lungs to relieve asthma and cough.  The skin of Varanus bengalensis is highly priced and is used widely in the manufacture of leather goods. During a survey in the winter of 2010 in northern Tamil Nadu, Bengal monitors were recorded in several places across a variety of habitats, suggesting a stable population. However, they are caught and killed mercilessly, and there is an illegal flesh trade of these reptiles in northern Tamil Nadu, which has led to them becoming endangered. Thus catching monitor lizards is banned under the Wildlife Protection Act (1972).   Surprisingly, V. bengalensis has been assessed as a species eliciting least concern by the IUCN Red List Category. Though it is listed as safe now, further research and monitoring of this species is needed to ensure that a threat category is not triggered in the future. The establishment and management of new protected areas where this species can be protected from hunting is needed to provide refuge sites from persecution. The Tokay gecko, Gekko gecko is much sought after in the pet trade. But recently there has been an increase in demand for its flesh, especially of the tongue, due to the belief that it is a cure for AIDS. Its carcass is dried and ground into powder for consumption.  After reports that the consumption of the Tokay geckos’ tongue and internal organs cure HIV, the demand for these geckos increased. It has also been used extensively for cures for impotence and illnesses such as diabetes, asthma, skin disease and cancer The demand has continued despite the World Health Organization's position that there is no cure for AIDS at present. 

Citation
Subramanean, J & Reddy, MV. 2012. Monitor lizards and geckos used in traditional medicine face extinction and need protection Current Science (Bangalore) 102, (9)1248-1249.

Lethally Hot Temperatures During the Early Triassic Greenhouse

A paleogeographic reconstruction of the Early Triassic world (Smithian substage) around 252-247 million years ago, showing a ‘dead zone’ in the tropics. Marine reptiles (ichthyosaurs), terrestrial tetrapods and fish almost exclusively occurred in higher latitudes (>30 °N and >40 °S) with rare exceptions. (Art Credit: Yadong Sun, University of Leeds)

Scientists have discovered why the ‘broken world’ following the worst extinction of all time lasted so long – it was simply too hot to survive.

The end-Permian mass extinction, which occurred around 250 million years ago in the pre-dinosaur era, wiped out nearly all the world’s species. Typically, a mass extinction is followed by a ‘dead zone’ during which new species are not seen for tens of thousands of years. In this case, the dead zone, during the Early Triassic period which followed, lasted for a perplexingly long period: five million years.

A study jointly led by the University of Leeds and China University of Geosciences (Wuhan), in collaboration with the University of Erlangen-Nurnburg (Germany), shows the cause of this lengthy devastation was a temperature rise to lethal levels in the tropics: around 50-60°C on land, and 40°C at the sea-surface.

Lead author Yadong Sun, who is based in Leeds while completing a joint PhD in geology, says: “Global warming has long been linked to the end-Permian mass extinction, but this study is the first to show extreme temperatures kept life from re-starting in Equatorial latitudes for millions of years.”

It is also the first study to show water temperatures close to the ocean’s surface can reach 40°C – a near-lethal value at which marine life dies and photosynthesis stops. Until now, climate modellers have assumed sea-surface temperatures cannot surpass 30°C. The findings may help us understand future climate change patterns.

The dead zone would have been a strange world – very wet in the tropics but with almost nothing growing. No forests grew, only shrubs and ferns. No fish or marine reptiles were to be found in the tropics, only shellfish, and virtually no land animals existed because their high metabolic rate made it impossible to deal with the extreme temperatures. Only the polar regions provided a refuge from the baking heat.

Before the end-Permian mass extinction the Earth had teemed with plants and animals including primitive reptiles and amphibians, and a wide variety of sea creatures including coral and sea lillies.

This broken world scenario was caused by a breakdown in global carbon cycling. In normal circumstances, plants help regulate temperature by absorbing Co2 and burying it as dead plant matter. Without plants, levels of Co2 can rise unchecked, which causes temperatures to increase.

The study, published today in the journal Science, is the most detailed temperature record of this study period (252-247 million years ago) to date.

Sun and his colleagues collected data from 15,000 ancient conodonts (tiny teeth of extinct eel-like fishes) extracted from two tonnes of rocks from South China. Conodonts form a skeleton using oxygen. The isotopes of oxygen in skeletons are temperature controlled, so by studying the ratio of oxygen isotopes in the conodonts he was able to detect temperature levels hundreds of millions of years ago.

Professor Paul Wignall from the School of Earth and Environment at the University of Leeds, one of the study’s co-authors, said: “Nobody has ever dared say that past climates attained these levels of heat. Hopefully future global warming won’t get anywhere near temperatures of 250 million years ago, but if it does we have shown that it may take millions of years to recover.”

The study is the latest collaboration in a 20-year research partnership between the University of Leeds and China University of Geosciences in Wuhan. It was funded by the Chinese Science Foundation.

Citation
Yadong Sun, Michael M. Joachimski, Paul B. Wignall, Chunbo Yan, Yanlong Chen, Haishui Jiang, Lina Wang, and Xulong Lai. Lethally Hot Temperatures During the Early Triassic Greenhouse. Science, 2012; 338 (6105): 366-370 DOI: 10.1126/science.1224126

Thursday, October 18, 2012

Timber Rattlesnakes & Fire

A black timber rattlesnake. JCM

Timber rattlesnakes (Crotalus horridus) are relatively widespread in the eastern US, and associated with forests. Beaupre and Douglas (2012) suggest they make excellent model organisms for understanding the effects of large scale habitat manipulations due to their low energy lifestyle, rapid response to changes in resources in the environment, and their uniform diet  of small mammals. They present two case studies that illustrate interactions between timber rattlesnakes and fire in a single large population in Madison County, Arkansas. The first case describes the decimation and subsequent 11 year recovery of a timber rattlesnake subpopulation associated with a fire during a particularly vulnerable time of year. In the second case four
control plots, three cut (thinned) plots, three burned plots, and three plots that were both cut and burned were studied. The primary goals were to monitor responses of the food chain to the above four treatments and to assess timber rattlesnake responses as potential indicators for the relative success of manipulations. Although plant communities did not initially differ among treatment plots, manipulated sites experienced increases in early-successional annual vegetation after thinning and burning. Biannual live-trapping  indicated an increase in abundance of principal prey species after manipulations, although this increase was not uniform among treatments. Timber rattlesnakes that utilized manipulated sites exhibited enhanced growth and body condition relative to snakes that foraged solely in control areas. Snake physiological responses were more
rapid and well-defined than measurable small mammal population responses suggesting that these top predators may potentially serve a role as indicator species for restoration ecology. The two case studies illustrate both direct and indirect effects, as well as dramatically divergent outcomes resulting from minor changes in the timing of fire application.  The entire article can be found on-line.

Citation
Beaupre, S. J. and Douglas, L.E. 2012. RESPONSES OF TIMBER RATTLESNAKES TO FIRE: 
LESSONS FROM TWO PRESCRIBED BURNS. Proceedings of the 4th Fire in Eastern Oak Forests Conference pages 192-204.

Wednesday, October 17, 2012

Gender & Life Span in Komodo Dragons

A female Komodo dragon guarding her nest in Indonesia. Credit: Tim Jessop
An international team of researchers has found that female Komodo Dragons live half as long as males on average, seemingly due to their physically demanding 'housework' such as building huge nests and guarding eggs for up to six months.

The results provide important information on the endangered lizards' growth rate, lifestyle and population differences, which may help plan conservation efforts.

The Komodo dragon is the world's largest lizard. Their formidable body size enables them to serve as top predators killing water buffalo, deer and wild boar and they have also been known to kill humans.

A research team which included scientists from the University of Melbourne, Australia, Indonesia and Italy studied 400 individual Komodo Dragons for 10 years in eastern Indonesia, their only native habitat. The team then produced a model of the Dragon's growth rate, with results published in the current issue of international journal Plos One.

Males live to around 60 years of age, reaching an average 160 metres in length and 65 kg at adulthood. However their female counterparts were estimated to live an average of 32 years and reach only 120 cm in length, and 22kg.

Dr Tim Jessop from the Department of Zoology at the University of Melbourne was a co-author on the study and said that the team were surprised by the significantly shorter lifespan of the female Komodo Dragon.

"The sex-based difference in size appears to be linked to the enormous amounts of energy females invest in producing eggs, building and guarding their nests. The process can take up to six months during which they essentially fast, losing a lot of weight and body condition, he said.

"Males and females start off at the same size until they reach sexual maturity at around seven years of age. From then on females grow slower, shorter and die younger."

The research team was keen to understand the growth rate of the Komodo Dragons as this critical process can indicate how the species prioritises its energy use in lifestyle and reproductive strategies. The results suggest that females have high energy 'costs' for reproduction resulting in their smaller size, whereas to reproduce successfully, males must keep increasing in size.

The results could have dramatic consequences for the endangered species as early female deaths may be exacerbating competition between males over the remaining females, possibly explaining why males are the world's largest lizards.

"These results may seem odd to humans when the life span between Australian men and women differ by five years. But each species has different strategies to pass on their genes. For example humans invest a lot of energy in few children as raising them is very energy intensive, whereas insects will have hundreds of offspring with no input into their rearing."

Citation
Rebecca J. Laver, Deni Purwandana, Achmad Ariefiandy, Jeri Imansyah, David Forsyth, Claudio Ciofi, Tim S. Jessop. Life-History and Spatial Determinants of Somatic Growth Dynamics in Komodo Dragon Populations. PLoS ONE, 2012; 7 (9): e45398 DOI: 10.1371/journal.pone.0045398

Sunday, October 14, 2012

A New Thai Parachute Gecko



Ptychozoon kaengkrachanense. Photo by M. Sumontha.
Seven species of parachute geckos of the genus Ptychozoan are known, there is now an eighth species Ptychozoon kaengkrachanense a Thailand endemic which inhabits montane evergreen forest in Kaeng Krachan National Park, in western Thailand. The new species differs from all known Ptychozoon species by having three dark dorsal chevrons between limbs insertions, homogeneous dorsal scalation without enlarged scales, original tail without long terminal flap, supranasals widely in contact, a continuous series of 14–19 enlarged precloacofemoral scales, bearing 13–17 pores in males, the absence of a predigital notch in the preantebrachial cutaneous expansion and the presence of cutaneous expansions on sides of head.
Ptychozoon kaengkrachanense is the fifth species of Ptychozoon recorded from Thailand, along with P. horsfieldii, P. kuhli, P. lionotum and P. trinotaterra. and it is the only Ptychozoon species endemic to Thailand. It is the 68th reptile species recorded from Kaeng Krachan National Park, which was already known to house the richest herpetofauna of all protected areas of Thailand and it thus reinforces the exceptional value of the park in terms of biodiversity and its conservation.

Citation
MONTRI SUMONTHA, OLIVIER S.G. PAUWELS, KIRATI KUNYA, CHAIWAT LIMLIKHITAKSORN, SIRICHAI RUKSUE, APIRAT TAOKRATOK, MICHEL ANSERMET & LAWAN CHANHOME 2012. A new species of Parachute Gecko (Squamata: Gekkonidae: genus Ptychozoon) from Kaeng Krachan National Park, western Thailand . Zootaxa 3513 68-78.

Saturday, October 13, 2012

Two recent publications on invasive snakes in the USA

Invasive species have become common place, and invasive snakes can cause considerable damage to the ecosystems they colonize. However, as ectotherms snakes are limited by temperatures and different species have evolved in different climates.

Jacobson et al. (2012) experimentally examined the ability of the Burmese python to survive winters north of southern Florida. Using daily high and low temperatures from October to February that occurred between 2005 and 2011 at Homestead, Orlando and Gainesville, Florida; and Aiken, South Carolina. And, they used minimum temperatures projected for python digestion (16 °C), activity (5 °C) and survival (0 °C). The mean low and high temperatures decreased northward from Homestead to Aiken and the number of days of freezing temperatures increased northward. They found digestion was impaired or inhibited for 2 months in the Everglades and up to at least 5 months in Aiken. The snakes' activity was increasingly limited at more northern localities during these months. A single bout of low and freezing temperatures results in python death. The capacity for Burmese pythons to successfully overwinter in more temperate regions of the USA is seemingly improbable because they lack the behaviors to seek refuge from the cold, and the physiology to tolerate the cold temperatures. Burmese pythons evolved in tropical Southeast Asia this area is the source of the Everglades Burmese pythons. The authors predict that it is unlikely the Burmese python they will be able to successfully expand to or colonize more temperate areas of Florida and adjoining states because of the lack of behavioral and physiological traits to seek refuge from cold temperatures.

The Brown treesnakes (Boiga irregularis) are perhaps the most studied invasive snake due to their colonization of Guam. A recent paper by Kahl et al. (2012) suggests that this mildly venomous, exotic snake species has the potential to become invasive in North America, Hawaii, and the Commonwealth of the Northern Mariana Islands. The brown tree snake is native to northern and eastern Australia, New Guinea, and other islands of northern and western Melanesia. The snake was first found outside its native range in 1953 on Guam. The exact date they reached the island is uncertain, but they are believed to have arrived on military cargo transport vessels some time during or just after World War II. During the years that followed, the population of brown treesnakes increased considerably on Guam. The snakes have extirpated or endangered many native animal populations, attacked pets and poultry, bitten humans, and caused power outages resulting in millions of dollars in damage. This snake species has been found on ships and aircraft, which have transported it to other islands in the Indo-Pacific, as well as Hawaii and the continental United States (i.e., Texas, Oklahoma, and Alaska) in military cargo. Because the U.S. military is expanding its bases on Guam, resulting in increased shipments and military movements from Guam to the United States, there is an increasing risk for brown treesnakes to invade the United States, as well as other islands in the Pacific. The authors note that two-thirds of the literature concerning brown treesnakes is in gray area publication outlets that can be difficult to ascertain. A literature review is offered to provide a background of past research on brown treesnakes. This review of literature elaborates on the native range, morphology, behavior, biology, ecology, venom, diet, reproduction, habitat, mortality, and control of the brown treesnakes.

Citations
Jacobson E. R., Barker, D. G., Barker, T. M., Mauldin, R., Avery, M. L., Engeman, R. and Secor, S. (2012), Environmental temperatures, physiology and behavior limit the range expansion of invasive Burmese pythons in southeastern USA. Integrative Zoology, 7: 271–285. doi: 10.1111/j.1749-4877.2012.00306.x

Kahl, S.S., Henke, S. E. , Hall, M. A. & Britton, D.K. 2012. Brown treesnakes: a potential invasive species for the United States. Human-Wildlife Interactions 6:181-203.

Thursday, October 11, 2012

An unusual method of nitrogenous waste excretion in the softshell turtle Pelodiscus sinensis

Pelodiscus sinensis Photo credit Bastet78
Chinese soft-shelled turtles are exquisitely adapted to their aquatic lifestyle, sitting contentedly on the bottom of brackish muddy swamps or snorkelling at the surface to breath. According to Y. K. Ip from the National University of Singapore, they even immerse their heads in puddles when their swampy homes dry up: which intrigued Ip and his colleagues. Why do these air-breathing turtles submerge their heads when they mainly depend on their lungs to breathe and are unlikely to breathe in water? Given that some fish excrete waste nitrogen as urea – in addition to ammonia – and expel the urea through their gills, the team wondered whether the turtles were plunging their heads into water to excrete waste urea through their mouths, where they have strange gill-like projections. Ip and his colleagues publish their discovery that turtles effectively urinate through the mouth in The Journal of Experimental Biology.

Purchasing turtles from the local China Town wet market and immersing them in water for 6 days, the team measured the amount of urea that passed into the turtles' urine and found that only 6% of the total urea that the animals produced was excreted through the kidneys. Removing the turtles from the water and providing them with a puddle to dip their heads into, the team noticed that the turtles submerged their heads occasionally and could remain underwater for periods lasting up to 100 minutes. They also calculated the excretion rate of urea through the mouth by measuring the amount of urea that accumulated in the water and found that it was as much as 50 times higher than the excretion rate through the cloaca. And when the team injected urea into the turtles and measured their blood- and saliva-urea levels, they realized that the saliva-urea levels were 250 times greater than in the blood. The turtles were dipping their heads into water to excrete urea through their mouths.

Knowing this, the team reasoned that the animals must produce a specialized class of protein transporters in their mouths to expel the waste and, as these transporters can be deactivated by phloretin, the team decided to test the effect of phloretin on the turtle's ability to excrete urea. When the turtles were supplied with phloretin in their puddle of water, they were unable to excrete urea from their mouths when they submerged their head. And when the team analysed the turtles' cDNA, they found that the animals carried a gene that was very similar to urea transporters found in other animals. Finally, they checked to see if the turtles express this gene in their mouths and found evidence of the mRNA that is necessary to produce the essential urea transporter, allowing the reptiles to excrete urea waste through the mouth.

So, why do Chinese soft-shelled turtles go to such great lengths to excrete urea through their mouths when most other creatures do it through their kidneys? Ip and his colleagues suspect that it has something to do with their salty environment. Explaining that animals that excrete urea have to drink a lot, they point out that this is a problem when the only water available is salty – especially for reptiles that cannot excrete the salts. The team says, 'Since the buccopharyngeal [mouth and throat] urea excretion route involves only rinsing the mouth with ambient water, the problems associated with drinking brackish water… can be avoided'

Citation
Y. K. Ip, A. M. Loong, S. M. L. Lee, J. L. Y. Ong, W. P. Wong, S. F. Chew. The Chinese soft-shelled turtle, Pelodiscus sinensis, excretes urea mainly through the mouth instead of the kidney. Journal of Experimental Biology, 2012; 215 (21): 3723 DOI: 10.1242/jeb.068916

Wednesday, October 10, 2012

Suizo Report -- 10-5 and 10-6-2012, Marty Speaks


Howdy Herpers,                             9 October 2012

Once again we let Marty Feldner, and his little ringtail, do the talking. I'll add some comments at the end, and bring out my own rant about this last weekend later in the week.
Marty writes:

With Quailmageddon 2012 upon us the decision was made to track snakes only during the nights of October 5 & 6 instead of during the day when hunters could see where we were hanging flags and, thereby, acquiring a completely different kind of target to kill...not that hunters EVER just shoot something to shoot something. Sometimes they use gas and set fire to those targets. Or use rocks. I'm not at all against hunting; there's little I like more to eat than game meat and given sufficient freezer space will happily participate in future hunting expeditions. And, yes, I know it is unfair to characterize all hunters as ones with the redneck mentality to kill anything that slithers BUT it makes no sense to take chances given knowledge of past incidences of ignorant and unnecessary snake killings by orange and camo-clad consumers of crappy canned American beer.

Arriving at the site Friday evening Roger and I were pleasantly surprised to find the site devoid of hunters and conditions beautiful for a night's stroll tracking snakes amongst the saguaros. Enjoying another outstanding sunset while mass signaling from the top of IMH I split from Roger to head after CT13. Due to how close CT13 appeared from her signal strength and how easy she'd be to get Roger was even kind enough to offer to open the data sheet he gave me. What a guy!...but then the tracking took place. She wasn't far, really, but she was in some of the rockier and more difficult terrain to traverse. No problem, and even though she wasn't visible, I got to spend more time with my furry tracking buddy. The ringtail showed up as I was changing batteries in the GPS before continuing on my circuitous route that would bring me back to the same general area on IMH to track the last snake of the night, CT12. On to the images which combine both nights of tracking.

Ringtail1-3 10-5-2012: At this point it wouldn't surprise me if people were starting to think, "Another damn ringtail report?" Yep, the novelty of one of the coolest nocturnal mammals that can't eat me has yet to wear off. We hung out for 10-15 minutes before I headed off. During that time, as the first picture indicates where there's a head peeking out of the space between boulders near my foot, the ringtail was even more comfortable to come near me. As I watched this lithe little mammal I couldn't help but be impressed with how fluidly and effortlessly it moved over and through the rocks checking out cracks, investigating opening and poking around attendant to its duties as a ringtail. It even stopped moving (second image) and laid down a couple meters from me at the edge of the rock ridge where CT13 resides. The last image shows the ringtail next to CT13's flag in front of the antenna. The next night the ringtail returned to keep myself and Jon Davis company and investigated the flag, nosing it and pulling at it with its teeth. CT13, again, wasn't visible and hadn't moved. The previous week CT13 had been on the E/SE slope of IMH, this week she was on the north slope at the east end of IMH.







CT11 10-6-2012: Male tiger CT11 was at a new site still on the bajada to the E/SE of IMH and occupied the same site both nights. I didn't get a visual on Friday night but saw him on Saturday night in a coiled hunting posture deep in prickly pear where he's looking to be in great health.


CM14-CM17 Copulation1-6 10-5-2012: CM11, Gus, has been associating with a big-headed female since at least September 16, making this the fourth weekend in a row of tracking where he's either been seen with, or thought to be with, the newest molossus to the study, CM17. And, she doesn't just have a big head. She's big all over. Not big in the same way as a fat girl that calls herself curvy...because she's actually attractive to the boys, or at least Gus. On Friday, a little after 2000h, I stumbled upon a romantic tryst involving spikey toys and wang-pulling.The 6 picture series shows CM11 and CM17 at their chosen nooky site of a cholla and stick midden built inside a prickly pear on Little Hill. The two had moved south and out of the wash occupied for the last two weekends. I watched for a little over 30 minutes as Gus chin-rubbed his way in jerking motions up and down CM17's flanks and back tongue-flicking as he went. At one point when I moved in to take a picture CM17 changed her position from being on CM11's left side to his right side, pulling him by his wang through cholla segments and prickly pear as she went, to move closer to where I was. Rattlesnakes are curious and I've had them change positions or exit refuge sites to investigate me and that is very much what it seemed CM17 was doing. 13 hours later Roger and I visited the snakes to find them still locked up...at least until CM17 saw Roger and ejected CM11's hemipene in a fashion similar to torpedo being blown out of a submarine's firing tube. He does have a way with the ladies! Now free of the cloacal embrace we decided to capture CM17 to increase molossus in the study to 3 adult males, 3 adult females, and 1 subadult male. When we took a mass CM17 weighed in at a whopping 746g. 





CA133 10-5-2012: CA133 has moved from a wash island in Suizo Wash NE of IMH to just south of Suizo Wash and is now in a tributary wash leading to Suizo Wash E of IMH. She was in a coiled hunting posture a couple meters away from a wash edge coiled under vegetation when found. During data recording she relocated to the base of a small mesquite and coiled about 2m away. 
Atrox and CT12 10-5-2012: Tracking female tiger CT12 brought me back to IMH where Roger was downhill tracking female molossus CM15. In trying to have a conversation with Roger from a distance I blew past CT12's location but in doubling back encountered an atrox coiled atop boulders that looked like a young male. CT12 was found not far away in a diagonal crack in a large boulder in a heads-up hunting posture. When tracked Saturday night she had moved a few meters uphill to a soil burrow associated with a large rock outcrop. It's interesting that the movements of female tigers CT12 and CT13 in terms of when they moved to IMH and what part of the hill they are using have often been similar during the last month.

CT14 10-6-2012: Roger and I woke Saturday morning to a surprising silence. We attributed hunter wussiness to the heat, but no matter what the cause, we were happy for it. The previous night we couldn't get signals for male molossus CM14 or male tiger CT14. We knew CM14 had relocated to the first canyon in the Suizos proper so we set out to track him, found that he'd moved a short distance, but was not visible. Then we tuned in CT14's signal and it came in loud and strong and, fortunately, in the direction towards the truck. CT14 was coiled underneath a small boulder on a west facing slope. Now the question is, does this become the overwintering canyon for the 14s? Or, will we see either of these snakes return to IMH?
CM15 10-6-2012: CM15 has moved from the foot of the eastern slope of IMH the previous week to an area on the north slope of IMH. She was in a coiled hunting posture in some dense vegetation when Jon spotted her.


Sunday morning we woke to the serenade of shotgun shells being spit over the Sonoran landscape and packed it up until next week.

In mid February of 2002, during the pistol/shotgun Javelina hunting season, I was observed by a hunter on a quad while writing up our black-tailed rattlesnake male CM4. The hunter was watching me with his binoculars about 20 meters below me. He eventually buzzed off. The snake was just outside of a den that we call "Jeff's Den," which is located on the south ridge of the Suizo Mountains proper. My first impulse was a good one: bag the snake, and bring it back after the hunt. Instead, I left it as it was. The next day, the snake, and the signal, were gone forever. I'll just stop there, and let that comment ride as a reason for my paranoia when the hunting seasons arrive.

The observation of the black-tails mating is significant in that it is the first time we've ever recording it. Back in 2001, we had a female, CM2, who drew in three different males. We at one point saw tails in alignment, but no insertion. That incident was in late September of 2001. The capture of this new female has our hopes up for seeing the other end of the spectrum: birthing in desert black-tails. Things are shaping up nicely for 2013!

It is interesting to note that this mating event in early October is the first time we've ever seen any mating of any species of rattlesnake in October--at least on the plot. We have seen countless acts of courtship with atrox--but never mating.

The show will go on!

Best to all, roger

Sunday, October 7, 2012

Why is Python bivittatus so successful in Florida?

Python bivittatus. JCM

Why has the Burmese python (Python bivittatus) been so successful at invading southern Florida while other species have been less successful  The invasive pythons have caused precipitous population declines among several species of native mammals.  Reed et al (2012) examine the reasons for the snake's success  by scoring the Burmese python for each of 15 literature-based attributes from a diverse range of taxa and provide a review of the natural history and ecology of Burmese pythons relevant to each attribute. The authors  focus on attributes linked to spread and magnitude of impacts rather than establishment success. Their results suggest that attributes related to body size and its generalist habits appear to be particularly applicable to the Burmese python's success in Florida. The attributes with the highest scores were: high reproductive potential, low vulnerability to predation, large adult body size, large offspring size and high dietary breadth. However, attributes of ectotherms in general and pythons in particular (including predatory mode, energetic efficiency and social interactions) might have also contributed to invasion success.

The  ranking exercise suggested that Burmese pythons might be somewhat atypical of boas and pythons in terms of their likelihood to spread as invasive species and impact native ecosystems. Burmese pythons ranked equal to, or higher than, a ‘typical’ boa or python species for every invasion-related trait we considered, and scored particularly high in traits related to size and degree of parental care. These traits, combined with their popularity in the pet trade and a large global climate match compared to the other giant constrictors likely make Burmese pythons a higher risk for introductions elsewhere.

Although establishment risk assessments are an important initial step in prevention of new establishments, evaluating species in terms of their potential for spreading widely and negatively impacting ecosystems might become part of the means by which resource managers prioritize control efforts in environments with large numbers of introduced species.

The article is available on-line.

Citation
REED, R. N., WILLSON, J. D., RODDA, G. H. and DORCAS, M. E. (2012), Ecological correlates of invasion impact for Burmese pythons in Florida. Integrative Zoology, 7: 254–270. doi: 10.1111/j.1749-4877.2012.00304.x

Urban Snakes from Brazil's Atlantic Forest

Helicops angulatus. JCM

Snake species living in urbanized areas are perhaps the most likely species to be studied. if for no other reason than the convenient access to the animals and study sites. While urban snake studies are relatively common in the USA and Eurasia, relatively few have been done in the tropics. Franca et al. (2012) describe the snake assemblage from the urban area of Rio Tinto city in Paraíba State, Northeast Brazil. They present data on composition and distribution as well as some natural history. Also, they compare the snake diversity of the urban area with the diversity in two nearby natural patches. The study included data on 161 individuals of 25 species in 16 genera from the urban area of Rio Tinto. Te most common species were:  Helicops angulatus, Bothrops leucurus, Epicrates assisi, and Philodryas patagoniensis. While most species were non-venomous, some venomous snakes were abundant in the urban area. Rarefaction curves did not reach stability and new species should be expected to be added to the Rio Tinto snake list in future studies.

The authors suggest that almost all snakes living in urban areas are continually under predation pressure from humans for several reasons. First, snakes are often killed whenever encountered by humans, who seldom discriminating between venomous and non-venomous species. Even plain gray or brown snakes, such as Liophis poecilogyrus or Philodryas patagoniensis, are considered by local people to be extremely dangerous. Almost all species documented in this study included at least one individual that had been killed by local people in Rio Tinto. Secondly, snakes must frequently cross roads in urban areas and are easy targets for drivers. Third, snakes in urban areas are subject to higher levels of parasitic infection and predation by exotic cats, dogs and chickens. Finally, habitat modification, loss, and fragmentation in urban areas can reduce food resources, reproduction sites, and gene flow, leading to local extinctions.Knowledge of the composition and abundance of snake species found in urban areas is an essential first step to understanding these relationships.  Urban ecosystems are increasing throughout the world, and urban ecology is attracting growing research interest and exploring the risks and benefits of snakes living in urban areas.

The entire article can be found on-line.

Citation
FRANÇA, R.C., GERMANO, C.E.S. & FRANÇA, F.G.R. Composition of a snake assemblage inhabiting an urbanized area in the Atlantic Forest of Paraíba State, Northeast Brazil. Biota Neotrop. 12(3): http://www.biotaneotropica.org.br/v12n3/en/abstract?inventory+bn00612032012

Friday, October 5, 2012

A Snail's Escape Response to Snake Predation


Snails that can shed their tails to escape much faster-moving predators and then regrow the amputated body section have been discovered living in sub-tropical Japan.

At left. The snail-eating snake Pareas iwasakii as it feeds on a snail. Bar= 10 mm. Photo credit: Masaki Hoso.

The ability to shed body parts, similar to that found in lizards, crabs and earthworms, has reportedly never before been seen in a mollusk.

Masaki Hoso, a Netherlands-based fellow with the Japan Society for the Promotion of Science, posted the findings on his website Wednesday, as his paper was published in the British science journal Proceedings of the Royal Society.

Hoso experimented with "isshikimaimai" snails (Satsuma caliginosa caliginosa) that live on the Okinawan islands of Ishigaki and Iriomote by feeding them to predator snakes, called Pareas iwasakii.

"It was found that isshikimaimai often escaped predation by detaching their own tails" before hiding themselves inside their shells, he said on his website, adding the cut-off sections were regenerated "a few weeks later".

Hoso also put the same kind of snakes together with a different type of snails from another Okinawan island, about 120 kilometres (75 miles) west of Ishigaki, where there are no snail-eating snakes.

"These snails do not cut off their tails at all and in the experiment they were easily eaten by Iwasaki's snail-eaters," he said.

"The autotomy of isshikimaimai is presumed to be a special case of adapting to counter snakes," said Hoso, a visiting researcher at the Naturalis Biodiversity Center in Leiden.

The tail shedding behaviour is frequently seen among the snails whose shell has yet to fully develop into an effective defence, the study said.

When the snails mature, the aperture of their shell becomes disfigured in a way that protects the creature when it retreats inside.

Hoso noted that while the tails of lizards are structured to be easily detached from the body trunks, no such special structure is present in the tail of isshikimaimai.

"The mechanism of the autotomy remains to be solved," he wrote.

Scientists have previously noted that Iwasaki's snail-eaters have asymmetrical jaws, with more teeth on the right side to allow for more efficient access to snail shells, which predominantly spiral clockwise.

Biologists in the US reported last month that the African spiny mouse, a desert rodent that has become an exotic pet, can shed up to 60 percent of the skin on its back and fully regrow the lost tissue.

The spiny mouse (Acomys) is well-known for eluding hunters by shedding its tail skin.

Understanding the trick could one day help burns victims in need of scar-free skin regeneration, scientists said.

The entire article is available on-line.

Citation
Hoso, M. 2012. Cost of autotomy drives ontogenetic switching of anti-predator mechanisms under developmental constraints in a land snail Proc. R. Soc. B , doi:10.1098/rspb.2012.1943 1471-2954

Wednesday, October 3, 2012

Suizo Report -- Hauling a$$ and sitting tight


Howdy Herpers, 10/03/12

In the report that went out yesterday, Marty had this to say about tracking our wayward male molossus CM14:

"Found this neonate solare as HW, Ryan and I attempted to track male CM14, the only snake Roger designated as a "MUST GET." Thanks for jinxing me! Roger and HW got his signal the night before so he might have booked and made a significant move or, for some reason, my receiver wasn't picking up his signal. Hopefully Roger was able to locate him Sunday."

Yes, H-W and I had his signal the night before. We got the signal from the windmill, which is located just south of the Suizo Mountains proper. But the closer we got to the foremost ridge, the quieter the signal got. This usually indicates that the animal is on the other side of the ridge. As it was already very late in the evening, it was decided to get CM14 in the morning.

And so, the aging team of Schuett and Repp decided to send the younger, stronger, faster men after the snake. As Marty suggests, a "must get" was written on the datasheet, with an arrow pointing directly at "CM14." Typing Boy here told them "I don't care if you don't get any others--just get this one. Once you get to the windmill, try him. I think he's in the next drainage north."

Somehow, this message did not come through. They tracked everything BUT the one we needed to get. When I chided them for this, (indicating in not-too-subtle a fashion that we had sent BOYZ to do a man's job), they informed me that I was getting fat, and needed the exercise. They were helping me to live a longer life. They had done me a HUGE favor.

That's what I like about these guys: nothing!

And so, the next evening, fat, dumb and happy here tried the signal from the windmill. Good old 12 - 2 on the dial of the same receiver I sent them out with the night before. Needless to say, it came in--loud and clear. Slackers! As surmised, the signal was actually coming from the next drainage north of the front ridge of Suizo Mountains Southwest. At first, I thought I was in for an easy track.

But up, up, up I went. Beyond the very last mountain my son Tim and climbed together back in the year 2000. Well above that, and well around the corner from it. Finally, he scores. There is CM14 coiled in a hunt posture, under a bursage and prickly pear. See image 1.

He had moved over a mile. The scary part is that we have two more big male molossus like this one, who will likely do the same thing.

Now, we move to the images. In doing so, we can thank Marty, H-W, and Ryan for not listening to me. Truth be told, I enjoyed every second of the monumental tracking episode with CM14. And thanks to the boys not listening to the man, we have some great sequence shots of a few individual snakes.

Image 1: Male CM14. My method of photographing a snake in situ is to fire a couple shots from the distance first observed, and then start closing in for the money shot. After this image was taken, the snake bolted. I'm glad to have this much, but it SHOULD have been better.

What a spoil sport of a snake!

Images 2-3: Female CM15 on the night of 28 September (Repp). Just after this shot was taken, she bolted under the boulder with a mylar balloon strewn in a nearby prickly pear, where Marty found her the next day (Image 3, Feldner).

Images 4-6: Male CM12 on the move. Image 4, (Feldner) has him on the SW side of IMH, near where we park. Image 5 (Repp) has him coiled at the southernmost tip of IMH, and image 6 has him abut 200 meters out into the bajada. (Dates are file extensions). 

Images 7-9: A classic sequence of a rattlesnake, female CT12, using sit-and-wait ambush techniques. Image 7 (Repp) shows her set up in the center of a dead clump of prickly pear--note the fruit all around her. Image 8 (Feldner) shows her THICK posterior going into a hole the next morning. No doubt, it gets VERY hot in that place by day. And the last image in this series shows her back out the following morning--in the EXACT spot she was two nights before.
We'll stop here. We look forward to what comes next.

Best to all, roger


Dwarf species of herbivorous fanged dinosaur from southern Africa

Art by Tyler Keillor
A new species of plant-eating dinosaur with tiny, 1-inch-long jaws has come to light in South African rocks dating to the early dinosaur era, some 200 million years ago.

This “punk-sized” herbivore is one of a menagerie of bizarre, tiny, fanged plant-eaters called heterodontosaurs, or “different toothed reptiles,” which were among the first dinosaurs to spread across the planet.

The single specimen of the new species was originally chipped out of red rock in southern Africa in the 1960s and discovered in a collection of fossils at Harvard University by Paul Sereno, paleontologist and professor at the University of Chicago and National Geographic Explorer-in-Residence. Details of the dinosaur’s anatomy and lifestyle are part of a monograph by Sereno dedicated to these puny herbivores and published in the online journal ZooKeys.

Named Pegomastax africanus, or “thick jaw from Africa,” the new species had a short, parrot-shaped beak up front, a pair of stabbing canines and tall teeth tucked behind for slicing plants. The tall teeth in its upper and lower jaws operated like self-sharpening scissors, with shearing wear facets that slid past one another when the jaws closed. The parrot-shaped skull, less than 3 inches long, may have been adapted to plucking fruit.

“Very rare,” contended Sereno, “that a plant-eater like Pegomastax would sport sharp-edged, enlarged canines” like that of a vampire. Some scientists have argued that consuming meat, or at the least, insects, was a good part of the diet of heterodontosaurs, which evolved near the root of the great radiation of dinosaurs that included the famous plant-eaters Triceratops and Stegosaurus.

Self-defense and competitive sparring for mates is more likely their role, argues Sereno in the study, based on microscopic examination of the teeth of Pegomastax and kin. Wear facets and chipped enamel suggest that the fangs of Pegomastax and other heterodontosaurs were used like those of living fanged deer for nipping or even digging, rather than slicing flesh.

A bizarre covering of bristles, something like that of a porcupine, likely covered most of the body of Pegomastax, which measured less than 2 feet in length and weighed less than a housecat. These bristles first came to light in a similar-sized heterodontosaur, Tianyulong, discovered recently in China and described in the study. Buried in lake sediment and covered by volcanic ash, Tianyulong preserves hundreds of bristles spread across its body from its neck to the tip of its tail. In life, dwarf-sized heterodontosaurs like Pegomastax would have scampered around in search of suitable plants, said Sereno, looking something like a “nimble, two-legged porcupine.”

When Pegomastax lived some 200 million years ago, the supercontinent Pangaea had just begun to split into northern and southern landmasses. Heterodontosaurs appear to have divided similarly, the study argues, the northern species with simple triangular teeth like Tianyulong and the southern species with taller crowns like Pegomastax.

Sereno marvels at these punk-sized early herbivores that spread across the globe. Although virtually unknown to the public, “Pegomastax and kin were the most advanced plant-eaters of their day.”

Citation:

Paul C. Sereno, “Taxonomy, Morphology, Masticatory Function and Phylogeny of Heterodontosaurid Dinosaurs,” ZooKeys online, Oct. 3, 2012.