Monday, March 25, 2013

Geckoella jeyporensis Rediscovered

Times of India, press release.
Geckoella jeyporensis


MUMBAI: Indian scientists have rediscovered a rare lizard that British colonel RH Beddome had last spotted in the Eastern Ghats in 1877.

"This elusive lizard, Geckoella jeyporensis, commonly named as Jeypore ground gecko, was believed to have become extinct since it was last seen in 1877. But in 2010-11, a PhD student of Centre for Ecological Sciences (CES), Ishan Agarwal, and his team spotted it again in Orissa,'' Bombay Natural History Society senior scientist Varad Giri told TOI.

Giri studied this rare find. "After properly studying its features and taxonomy, we were thrilled to learn that this is the same gecko which became 'extinct' 135 years ago. This rediscovery was recently published in the scientific journal of Hamadryad,'' said Giri.

The published work was the result of two years of collaboration between scientists from the CES, Indian Institute of Science, Bangalore; Bombay Natural History Society, Mumbai; and Villanova University in the US.

The story of the rediscovery began in 2008-09, when Agarwal began working on the genus Geckoella. Ishan was desperate to find this lost species to understand more about its evolutionary history.

Finally, in 2010, a team from CES embarked on a trip to try and locate this species. The team included two members of the Karanth Lab, CES, Ishan Agarwal and Aniruddha Datta-Roy and their field assistant, Tarun Khichi.

They managed to find the Geckoella jeyporensis. The team re-assembled in 2011 and was able to find the species again in Andhra Pradesh.

Citation
Agarwal, Ishan, Aniruddha Datta-Roy, Aaron M. Bauer and Varad B. Giri. 2012. Rediscovery of Geckoella jeyporensis (Squamata: Gekkonidae), with notes on morphology, coloration and habitat. Hamadryad 36 (1): 17-24

Wednesday, March 20, 2013

Evolution of microcephalic sea snakes

Hydrophis cf gracilis. JCM
An international team of scientists led by Dr Kate Sanders from the University of Adelaide, and including Dr Mike Lee from the South Australian Museum, has uncovered how some sea snakes have developed 'shrunken heads' -- or smaller physical features than their related species.

Their research is published today in the journal Molecular Ecology.

A large head -- "all the better to eat you with" -- would seem to be indispensable to sea snakes, which typically have to swallow large spiny fish. However, there are some circumstances where it wouldn't be very useful: sea snakes that feed by probing their front ends into narrow, sand eel burrows have evolved comically small heads.

The team has shown normal-shaped sea snakes can evolve such "shrunken heads" very rapidly. This process can lead to speciation (one species splitting into two).

The small-headed populations are also much smaller in absolute size than their ancestors, and these shape and size differences mean they tend to avoid interbreeding with their large-headed ancestors.

Dr Lee says, "A team led by my colleague Dr Kate Sanders (University of Adelaide) has been investigating genetic differences across all sea snakes, and we noticed that the blue-banded sea snake (Hydrophis cyanocinctus) and the slender-necked sea snake (Hydrophis melanocephalus) were almost indistinguishable genetically, despite being drastically different in size and shape.

"The slender-necked sea snake is half the size, and has a much smaller head, than the blue-banded sea snake.

"This suggested they separated very recently from a common ancestral species and had rapidly evolved their different appearances.

"One way this could have happened is if the ancestral species was large-headed, and a population rapidly evolved small heads to probe eel burrows -- and subsequently stopped interbreeding with the large-headed forms."

Dr Sanders says the research could have wider implications in other scientific studies: "Our results highlight the viviparous sea snakes as a promising system for studies of speciation and adaptive radiation in marine environments."



Citation
Kate L. Sanders, Arne R. Rasmussen, Mumpuni, Johan Elmberg, Anslem de Silva, Michael L. Guinea, Michael S. Y. Lee. Recent rapid speciation and ecomorph divergence in Indo-Australian sea snakes. Molecular Ecology, 2013; DOI: 10.1111/mec.12291

Rediscovery of the Martinique dendrobatid frog Allobates chalcophis

Allobates chalcopis Photo credit: Fey Magazine

The native herpetofauna of the Lesser Antilles is made up of a relatively few families. Most of the Lesser Antilles native amphibians belong to the genus Eleutherodactylus that have direct development. Eleutherodactylus frogs radiated early in the Greater Antilles  and subsequently dispersed towards the Lesser Antilles. A few amphibians dispersed over water from South America into the Lesser Antilles, an idea supported by molecular data. These include: Leptodactylus fallax, Pristimantis euphronides and P. shrevei. Other clades of small terrestrial vertebrates from mainland South America are also represented in the island chain, particularly snakes, anoles and skinks.

One species of dendrobatidae frog was discovered in 1984 on Martinique, it was described in 1994, but despite field work to locate the species cause it was not found again. The original description suggested that Allobates chalcopis may be the sister taxon to Mannophryne on because they shared a dark throat collar and occurrence of Mannophryne in northern Venezuela and Trinidad and Tobago. However, using morphology and karyotype the species was allocated to the dendrobatid genus Allobates.

Now, 20 years after the last observation of the species, Fouquet and colleagues (2013) located an isolated population of Allobates chalcopis in Martinique. The rediscovery allowed the species’ phylogenetic position to be confirmed. It is nested within a clade of lowland Amazonian Allobates but nonetheless distantly related to any known species of the group. The arrival of the species in Martinique likely corresponds to an overseas dispersal from South America during the late Miocene. A point in time previously hypothesized for the arrival of Bothrops lanceolatus and Leptodactylus fallax; two other species endemic to Martinique and surrounding islands. Of interest  the species was not found at its type locality (500 m ASL) but 300 m higher in altitude The frogs habitat had shifted upward, and the frog was found in herbaceous areas near the summit of Mt. Pelee. The authors suggest the need for a reassignment of the current Red List status.

Antoine Fouquet , Kévin Pineau , Miguel Trefaut Rodrigues , Julien Mailles , Jean-Baptiste Schneider, Raffael Ernst & Maël Dewynter (2013) Endemic or exotic: the phylogenetic position of the Martinique Volcano Frog Allobates chalcopis (Anura: Dendrobatidae) sheds light on its origin and challenges current conservation strategies, Systematics and Biodiversity, DOI:10.1080/14772000.2013.764944

Monday, March 18, 2013

Attempts to clone the gastric brooding frog


Mar. 15, 2013 — The genome of an extinct Australian frog has been revived and reactivated by a team of scientists using sophisticated cloning technology to implant a "dead" cell nucleus into a fresh egg from another frog species.

The bizarre gastric-brooding frog, Rheobatrachus silus -- which uniquely swallowed its eggs, brooded its young in its stomach and gave birth through its mouth -- became extinct in 1983.

The gastric-brooding frog, Rheobatrachus silus, giving 
oral birth in the lab of Mike Tyler of the University of
 Adelaide.  (Credit: Mike Tyler, University of Adelaide)
But the Lazarus Project team has been able to recover cell nuclei from tissues collected in the 1970s and kept for 40 years in a conventional deep freezer. The "de-extinction" project aims to bring the frog back to life.

In repeated experiments over five years, the researchers used a laboratory technique known as somatic cell nuclear transfer. They took fresh donor eggs from the distantly related Great Barred Frog, Mixophyes fasciolatus, inactivated the egg nuclei and replaced them with dead nuclei from the extinct frog. Some of the eggs spontaneously began to divide and grow to early embryo stage -- a tiny ball of many living cells.

Although none of the embryos survived beyond a few days, genetic tests confirmed that the dividing cells contain the genetic material from the extinct frog.

The results are yet to be published.

"We are watching Lazarus arise from the dead, step by exciting step," says the leader of the Lazarus Project team, Professor Mike Archer, of the University of New South Wales, in Sydney. "We've reactivated dead cells into living ones and revived the extinct frog's genome in the process. Now we have fresh cryo-preserved cells of the extinct frog to use in future cloning experiments.

"We're increasingly confident that the hurdles ahead are technological and not biological and that we will succeed. Importantly, we've demonstrated already the great promise this technology has as a conservation tool when hundreds of the world's amphibian species are in catastrophic decline."

The technical work was led by Dr Andrew French and Dr Jitong Guo, formerly of Monash University, in a University of Newcastle laboratory led by frog expert, Professor Michael Mahony, along with Mr Simon Clulow and Dr John Clulow. The frozen specimens were preserved and provided by Professor Mike Tyler, of the University of Adelaide, who extensively studied both species of gastric-brooding frog -- R. silus and R. vitellinus -- before they vanished in the wild in 1979 and 1985 respectively.

UNSW's Professor Archer spoke publicly for the first time today about the Lazarus Project and also about his ongoing interest in cloning the extinct Australian thylacine, or Tasmanian tiger, at the TEDx DeExtinction event in Washington DC, hosted by Revive and Restore and the National Geographic Society.

Researchers from around the world are gathered there to discuss progress and plans to 'de-extinct' other extinct animals and plants. Possible candidate species include the woolly mammoth, dodo, Cuban red macaw and New Zealand's giant moa.

Invasive American bullfrog diet in Canada


American bullfrogs are native to eastern North America but have been transported by people to many other parts of the globe, and other parts of North America, where they have readily established populations and become an invasive alien menace to native ecosystems. In the largest study of its kind to date, the stomach contents of over 5,000 invasive alien American bullfrogs from 60 lakes and ponds on southern Vancouver Island were examined to identify the native and exotic animals that they had preyed upon.

Over 15 classes of animals were reported from a total of 18,814 identifiable prey remains, including terrestrial and aquatic insects, spiders, crayfish, fish, frogs, salamanders, newts, snakes, lizards, turtles, birds, and small mammals. The study examined the stomach contents of adults and juveniles of all size-classes, but excluded tadpoles. These results show that bullfrogs will attack and consume virtually any organism that is within reach and can be swallowed, including their own species.

Previous studies on bullfrog diet have examined relatively small numbers of stomachs from a comparatively small number of lakes and ponds. Our results reinforce the general consensus that there is good reason for concern about the ecological harm that uncontrolled populations of American bullfrogs might have, or are having, on populations of native species.

For decades, bullfrogs have been transported and released around the world by prospective frog-farmers, pet owners, game managers, recreational fishermen, biological supply houses; and even by entrants in frog jumping contests. They adapt readily to a variety of habitats from the tropics to temperate zones and once established, their numbers grow fast with each adult female producing about 20,000 or more eggs per year. For these reasons, American bullfrogs are internationally recognized as one of the 100 worst invasive alien species in the world.

Citation
Jancowski, K. & Orchard, S. 2013. Stomach contents from invasive American bullfrogs Rana catesbeiana (= Lithobates catesbeianus) on southern Vancouver Island, British Columbia, Canada. NeoBiota, 16 (0): 17 DOI: 10.3897/neobiota.16.3806

Thursday, March 14, 2013

47 Turtle and Tortoise Species to Receive Greater Legal Protection

Blanding’s Turtle. JCM
The CITES meeting in Bangkok has produced a lot of news about elephants, both good and bad. But the CITES treaty covers scores of protected species of all different classes, which is still only a fraction of the species worldwide that are under threat. Today produced some good news for fans of reptiles, as a total of 47 turtle and tortoise species were added to CITES appendices, including three species of pond turtle from the US. Over 200 countries ratified the proposals, including the US and China, who actually agreed on CITES regulation for reportedly the first time.

The US turtles added are Blanding’s turtles, spotted turtles and diamondback terrapins, which are all popularly traded in Asian food and medicine markets. According to the Center for Biological Diversity, over two million live turtles are exported from the US to Asian markets each year. While that figure includes species other than the three listed above, that huge catch has depressed a number of freshwater turtles. The new CITES coverage, which the CBD proposed way back in 2011, will at least force the trade to be regulated, monitored, and sustainable.

"I’m so pleased that the nations of the world are acting to save freshwater turtles in the United States,” said Collette Adkins Giese, a CBD attorney who focuses on reptiles and amphibians. “International protection is vital for the survival of our wild freshwater turtles, which are suffering from overexploitation, habitat loss and other threats.”

As you might have guessed, that huge Asian appetite for turtles has caused problems for turtle species in that region. In 2011, the Wildlife Conservation Society released a report listing the top 25 most endangered turtle species, nearly 70 percent of which were endemic to Asia. Along with the trio of North American turtles, a whopping 44 Asian turtle and tortoise species were given the protection of trade restrictions at the CITES conference.

Those restrictions can be flat-out bans, like for the international trade in ivory and rhino horn, which are generally reserved for endangered species and which are listed on CITES Appendix I. Appendix II, which a trio of hammerheads were added to this year, is for species that aren't necessarily endangered, but which are heavily threatened by market demand and whose trade must be regulated to be sustainable. Most of the turtles newly listed by CITES were added to Appendix II, while a few species have been bumped up to Appendix I, including Indonesia's Roti Island snake-necked turtle.

It's all good news, for as we've seen, conserving threatened species which have a high market demand is difficult enough when restrictions are in place. Without those restrictions, it's basically a free for all. Hopefully the new regulations will help preserve turtles for some time to come.

Eight new frogs described from Sri Lanka, seven are considered threatened


Sri Lanka has a remarkably diverse herpetofauna for its size. The Peak Wilderness area, part of the Central Hills, was designated a World Heritage Site. Geographical protected area is about 240 sq.km, of which 211.75 sq.km comprises natural or semi natural vegetation; the rest is no longer forest and includes tea estates and village settlements. Much of the terrain is  rugged, with altitudes ranging from 600 m to 2,238 m. The most recently described  vertebrate species in the area studied area were the gecko Cnemaspis samanalensis, and two skink:  Lankascincus munindradasai, and Lankascincus sripadensis suggesting the area is a center of endemicity.

The high altitudes, heavy rainfall, and steep topography make fiewld work difficult. In a just published article  Wickramasinghe et al. (2013) describe eight new species of rhacophorid frogs in the genus Pseudophilautus (Pseudophilautus bambaradeniyai, P. dayawansai, P. jagathgunawardanai, P. karunarathnai, P. newtonjayawardanei, P. puranappu, P. samarakoon, and P. sirilwijesundarai). They were discovered as a result of a survey to study the herpetofaunal diversity. The conservation status of all species described here, have been considered Critically Endangered, except for P. newtonjayawardanei.

All the new species are recorded from single locations, and their habitats are under severe threat. Human activity in the area is considerable, despite the difficult terrain. The highest point of this mountain range is a place of worship for all religions in the country and a place of aesthetic beauty. Millions visit the site every year during the pilgrim season which lasts for a period of six months. Large amount of garbage gets collected, and the primary forest is over exploited. Illegal gem mining occurs on both sides of the river bank. Tea cultivation in the surrounding area is slowly expanding; and Illegal tree felling to cultivate tea, has become a serious problem.

Citation
Wickramasinghe, L.J.M., D.R. Vidanapathirana, M.D.G. Rajeev, S.C. Ariyarathne, A.W.A. Chanaka, L.L.D. Priyantha, I.N. Bandara & N. Wickramasinghe (2013). Eight new species of Pseudophilautus (Amphibia, Anura, Rhacophoridae) from Sripada World Heritage Site (Peak Wilderness), a local amphibian hotspot in Sri Lanka. Journal of Threatened Taxa 5(4): 3789–3920; doi:10.11609/JoTT.o3099.3789-920

Medical risks from colubroid snakes


Rhabdophis subminiatus, a Hazard Level 1 species. JCM
Facts that don fit  existing knowledge are frequently clues to a greater understanding of nature. And, the fact that snakes without front fangs  could deliver venom has produced a greatly improved knowledge of snake evolution. as well as evolution in a general sense.

In the late 1960's a visit to a Miami animal dealer revealed the diversity of snake species in the pet trade. Besides the usual large boas and pythons, the dealer had green mambas, forest cobras, bushmasters, and cages filled with other species that I could not identify. But there was one cage that had a pile of green and brown snakes, that I did recognize, boomslangs.

The front-fanged snakes were known to carry venom and the anatomy to deliver it. But, at the time I was aware that some colubrid snakes, snakes thought to be harmless,  could also do serious harm to human health. The best know instance at the time  was the death of K. P. Schmidt in 1957 . Schmidt was Curator Emeritus at the Field Museum, when he was bitten identifying a boomslang for the Lincoln Park Zoo. Envenomation from colubrid snakes was relatively rare and reactions to bites from colubrid snakes was frequently attributed "allergic reactions" to saliva.

Antivenom for front-fanged snakes has been around for the last century, but venom  for rear-fanged snake bites as been slow in coming. In a forthcoming article in Toxicon, Weinstein and colleagues look at the evidence for health risks from the bites of non-front-fanged colubroid snakes (NFFC).  Until now a relatively few species of NFFC have been documented to be a medical risk to humans, but the authors point out a growing number of NFFC are implicated in medically significant bites. More NFFC species are entering the commercial snake trade and pose an uncertain risk. Weinstein and colleagues examined published case reports describing NFFC bites and used a meta-analysis yo generate a hazard index for select taxa. They also included cases on which they had consulted or personally treated.

About 120 species met the selection criteria, and a small subset were designated Hazard Level 1 (most hazardous), this group contained five species with lethal potential.Three species, Dispholidus typusRhabdophis tiginisRhabdophis subminiatus, have available antivenom. The other two - birds snakes -in the genus Thelotornis lack commercially available antivenoms. Bites from these snakes are treated with plasma/erythrocyte replacement therapy and supportive care. Heparin, antifibrinolytics and plasmapheresis/exchange transfusion have been used in the management of some Hazard Level 1 envenomings, but evidence-based analysis positively contraindicates the use of any of these interventions. Hazard Level 2/3 species involved in cases that contained mixed quality data and implicated three species: Boiga irregularisPhilodryas olfersii, and Malpolon monspessulanus. The bites of these snakes have rare systemic effects. Management of these bites may include use of acetylcholinesterase inhibitors and wound care on a case-by-case basis. Hazard level 3 is a large group of taxa capable of producing significant local effects (no systemic effects), symptoms are often associated with a protracted bite, species in this group include: Heterodon nasicusBorikenophis portoricensis, and Platyceps rhodorachis. Bite management is restricted to wound care. Hazard level 4 species comprised the majority of species surveyed and these showed only minor effects of no clinical importance.

As snakes become more popular as pets bites from these animals are likely to increase in frequency. But perhaps more important than knowing the risk to humans is the knowledge gained about the evolution of venom  and the increased potential for new molecules for research.

Citation
Weinstein, S.A., et al., Non-front-fanged colubroid snakes: A current evidence-based analysis of medical significance, Toxicon (2013), http://dx.doi.org/10.1016/j.toxicon.2013.02.003

Monday, March 11, 2013

Frogs of the northern Western Ghats

Two frogs found in Phansad Wildlife Sanctuary. Spaerotheca breviceps (left) a species found to be relatively common, and Ramanella mororata (right) a species found at only two localities in the sanctuary. Photo credit: U. Katwate.

The Western Ghats of southwest  India are well known foramphibian diversity, with thearae containing 187 species of amphibians, or about 2.7% of the worlds amphibian fauna.  Of the 183, 162 (88.5%) are endemic. Deforestation, changes in land use, urbanization and industrialization and the pathogenic fungus are major threats for Western Ghats amphibians.  Only 9% of the 160,000km2 area of the Western Ghats protected as national parks and wildlife sanctuaries.

Amphibians of the northern Western Ghats are less studied compared to the central and the southern Western Ghats. Katwate et al. (2013) surveyed anuran diversity at the northern Phansad Wildlife Sanctuary and found 22 anuran species, eleven are endemic to the Western Ghats biodiversity hotspot. Members of the family Dicroglossidae are species-rich within this area. Most of the endemic and threatened anurans are associated with patches of undisturbed evergreen  forest. Habitat parameters such as humidity, forest type, canopy coverage, riparian canopy coverage, stream persistence and litter depth are variables governing species diversity and distribution. The entire article is available on-line.

Two frogs found in Phansad Wildlife Scantuary. Spaerotheca breviceps a species found to be relatively common, and Ramanella mororata a species found at only two localities in the sanctuary. Photo credit: U. Katwate.

Katwate, U., D. Apte & R. Raut (2013). Diversity and distribution of anurans in Phansad Wildlife Sanctuary (PWS), northern Western Ghats of India.  Journal of Threatened Taxa 5(2): 3589–3602; doi:10.11609/JoTT.o3038.3589-602

Lizards, temperatures & the future

Sonoran Spiny-tailed Iguana, Ctenosaura macrolopha, juvenile. JCM 

Two papers published early on-line suggest lizards are facing a difficult future due to climate change. Both papers examine the role of temperature on lizard life history. Grigg and Buckley (2013) phylogeny and geography constrain thermal tolerances of lizards similarly within continents, but they are variably within clades. Conservative nature  of thermal tolerances across lineages suggests that the potential for local adaptation to alleviate the impacts of climate change on lizards is most likely limited.

A second study by Meiri et al (2013) used a data set that included 861 lizard species and looked at the relationship between lizard body temperature and environmental temperature. They tested for the influence of both body and environmental temperatures on ecological and life-history traits while considering the influence of common ancestry.

Meiri et al found body temperatures and mean annual temperatures are uncorrelated. However, when they considered: activity time (nocturnal species have low body temperatures), use of space (fossorial and semi-aquatic species are ‘colder’), insularity (mainland species are ‘hotter’) and phylogeny, the two temperatures are positively correlated. High body temperatures are only associated with larger hatchlings and increased rates of biomass production. They also found annual temperatures are positively correlated with clutch frequency and annual longevity, and negatively correlated with clutch size, age at first reproduction and longevity.

Therefore, they conclude that species with low body temperatures do not seem to have ‘slower’ life-history attributes than species with high body temperatures. The longer seasons prevalent in warm regions, and physiological processes that operate while lizards are inactive (but warm enough), make environmental temperatures better predictors of lizard life-history variation than body temperatures. This surprisingly greater effect of environmental temperatures on lizard life histories hints that global warming may have a profound influence on lizard ecology and evolution.

Citations
Grigg J. W. and L. B. Buckley. 2013.Conservatism of lizard thermal tolerances and body temperatures across evolutionary history and geography. Biology Letters (2) doi: 10.1098/rsbl.2012.1056.

Meiri, S., Bauer, A. M., Chirio, L., Colli, G. R., Das, I., Doan, T. M., Feldman, A., Herrera, F.-C., Novosolov, M., Pafilis, P., Pincheira-Donoso, D., Powney, G., Torres-Carvajal, O., Uetz, P. and Van Damme, R. (2013), Are lizards feeling the heat? A tale of ecology and evolution under two temperatures. Global Ecology and Biogeography. doi: 10.1111/geb.12053

Sunday, March 10, 2013

It is that time of the year: rattlesnake slaughter events



While some progress has been made in reducing the over all number of rattlesnake round-ups.  The largest of these events - the Sweetwater Oklahoma Rattlesnake Roundup- was held this weekend.  One blog post writer,
"This weekend is the largest rattlesnake round-up in Texas. The way the snakes are treated before they are slaughtered for public entertainment is sickening. I'd been posting on the Jaycees website all day, leaving polite messages about alternatives, such as the way Georgia turned their round ups into wildlife festivals (though it took the near decimation of the Eastern Diamondback population in Georgia for this to happen). 
"I've now been blocked from posting or commenting on the page."
The writer urges people to express their outrage at https://www.facebook.com/pages/Sweet...p/253049219648

Another writer, left the following message for Outboors720 editor.
"Dear Outdoors720 Editor, I stumbled upon your article by David Strege on the rattlesnake round-up in Texas.  This event is deplorable and your coverage of it seems laughable given that you seem to promote outdoor "enjoyment".  Please visit the website of HerpNationMedia so that you and your writers can get educated on why this event is so destructive (although as a herpetologist and a nature-lover this seems self-evident).  Would you cover a story on a feral cat round-up and extermination event?  What about feral dogs?  That sounds like great fun in the great outdoors, no? One could argue at least that dogs and cats are not native to North America and important to maintaining the integrity of the natural ecosystem.   
"The signs of a good writer, educator, promoter, etc., of the outdoors or nature would ask tough questions.  Like, how many people die or become injured from snake bites every year? How can farmers protect themselves and build corridors of native habitat to keep rattlesnakes in locations remote from where they work every day? It is disappointing that you do not use your site to encourage the preservation of the very outdoors that you claim to embrace; creatures with feathers, fangs, or venom are what make up our great outdoors.  
"Therefore many of us protest the destruction of our native herpetofauna."
http://www.outdoors720.com/
Arguing against rattlesnake roundups on humane grounds is likely lost on many of the active participants in these events. Instead they should be bombarded with the consequences of removing predators from ecosystems. When one predator disappears, others follow. Reduce the predators of rodents and diseases increase, diseases that impact livestock as well as humans. Getting legislation passed to prevent the events is the ultimate solution, but it will need to be done state by state.




Thursday, March 7, 2013

Two sand-dune dwelling snakes avoid direct competion


Sand Viper, Cerastes vipera.

The Saharan sand viper, Cerastes vipera , and the crowned leafnose, Lytorhynchus diadema  belong to different clades but well adapted to life in desert sand dunes. In Israel, and in all Saharan countries both coexist in sand and dune systems.   The two species have several characteristics in common: they are sand-dwelling; active under the same climatic conditions; nocturnal; feed mostly on lizards; and are relatively small – 35 cm for the sand viper and 50 cm for the crown leaf-nose snake. However, they differ in that the sand viper moves by side-winding  while the crowned leafnose snake uses serpentine movement; and the sand viper is a ambush predator, while the crowned leafnose snake is an active forager.

In a forthcoming article Sivan et al. (2013) test the hypothesis that sympatric sand vipers and crown leaf-nose snakes partition niches in terms of temporal activities and diet. They predicted that the two species would differ in their seasonal and daily patterns of activity as well as in the composition of their diets. To test these predictions they determined temporal activities, for both. Both were active from early spring until late fall but displayed  different seasonal activity patterns, the sand viper was bimodal with activity peaks in spring and autumn. The crowned leafnose was unimodal with a peak in summer. The sand viper was active  during the first three hours of darkness while the crown leaf-nose snake was  active during the first seven hours of darkness. Also the two species showed different patterns of nocturnal behavior: the sand viper moved up to 50 m while the crowed leafnosed snake moved several hundred meters each night. Prey included the Nidua fringe-fingered lizards (Acanthodactylus scutellatus) for both species. But the viper also consumed the skink Chalcides sepsoides and the crowned leafnosed snake gecko ate the gecko Stenodactylus petrii as well as reptiles eggs. The authors concluded that temporal partitioning in above-ground activity, distinctly different foraging strategies, and slightly different diets contribute to the coexistence of the two species.

Citation
Sivan, J., M. Kam, S. Hadad, A. A.Degen, I. Rozenboim,A. Rosenstrauch. 2013. Temporal activity and dietary selection in two coexisting desert snakes, the Saharan sand viper (Cerastes vipera) and the crowned leafnose (Lytorhynchus diadema). Zoology, http://dx.doi.org/10.1016/j.zool.2012.09.002

Opossums, pitvipers, & venom resistance

Bushmasters are one of the snakes known to feed on venom-resistant opossums

Opossums and pitvipers are sympatric throughout most of the New World. Opossums are were not known to feed on pit vipers and pit vipers were not known to feed on opossums. In the mid 1940 Vellard discovered that three species South American Didelphis were resistant to the venom of several pitviper species. The resistance is from endogenous toxin-neutralizing serum proteins, and possibly other molecules. Vellard proposed that venom resistance evolved as an adaptation for preying on venomous snakes at the same time  he  implied the hypothesis might be proven wrong if opossums too small to eat venomous snakes, were also found to be venom resistant. Later researchers reported venom resistance in the North American opossum (Didelphis virginiana), as well as several Neotropical opossums such as, the lutrine opossum ,and the gray four-eyed opossum  To date, all of the species found to be venom resistant belong to the Didelphini clade all and are relatively large, about 500 g, and are known to feed on pit vipers. By contrast, experiments have demonstrated the brown four-eyed opossum, a small (200-300 g) species is not resistant to snake venom.

Voss (2013) reviewed the literature records of snakes feeding on opossums and found that snakes feeding on large, venom resistant opossums were sometimes based upon mis-identifications. He did find that (1) some pitvipers are preyed upon by large venom-resistant opossums; (2) many small opossums that are not known to be venom-resistant are preyed upon by pitvipers; and (3) venom-resistant opossums are preyed upon by some large pitvipers. The last situation has not been previously recognized in the literature Voss suggests two possible explanations. First, venom may be able to overcome the resistance if young individuals of venom-resistant species are bitten by large snakes. Secondly some pitvipers may have evolved unusually potent venom as a result of co-evolution with venom-resistant predatory opossums.

Citation
Voss, R. S. 2012. Opossums (Mammalia: Didelphidae) in the diets of Neotropical piutvipers (Serpentes: Crotalinae): evidence for alternative coevolutionary outcomes? Toxicon 66:1-6.

The problem with bullfrogs in Southeast Asia

Lithobates catesbeiana
A team of scientists led by the Wildlife Conservation Society (WCS) and the National University of Singapore (NUS), revealed in a new study, for the first time, the presence of the pathogenic chytrid fungus (Batrachochytrium dendrobatidis) in amphibians sampled in Singapore. And the American bullfrog may be a central player in the spread of the disease.

The study appears in the current issue of the journal EcoHealth, and is the first to consider the role that Southeast Asia's commercial trade plays in the spread of amphibian pathogens.

Demand for amphibians through local and international trade is high and fueled by use of frogs as pets, food, bait, and as a source of traditional 'medicine.' More than 40 percent of amphibian species are in decline globally due, not only to chytrid fungus, but also overharvesting, competition from invasive species, habitat loss, pollution, and climate change.

In the study, scientists collected samples from 2,389 individual animals in Lao PDR, Cambodia, Vietnam, and Singapore at 51 different sites including farms, locally supplied markets, pet stores, and from the wild.

The molecular testing of samples was led by Dr. Tracie Seimon at WCS's Molecular Diagnostic Laboratory at the Bronx Zoo. Results showed that frogs from Lao PDR and Vietnam tested negative for chytrid. In Cambodia, one frog intended for food tested positive. In addition, 74 animals in Cambodia and Vietnam were screened for ranavirus and tested negative, suggesting that these specific pathogens are not yet a conservation threat in species tested from these countries.

In Singapore, however, 13 samples tested positive for chytrid and represent the first report of chytrid in the territory. Eleven of those samples were collected from four pet stores and the remaining two were taken from amphibians in the wild.

The scientists noted that the chytrid detections were most prevalent in the American bullfrog (Lithobates aka Rana catesbeiana), a common species in the trade and one that is tolerant of chytrid infections.

"Finding chytrid in four of the seven Singaporean pet stores we sampled is cause for concern," said lead author and WCS Scientist Martin Gilbert. "Since the American bullfrog is able to tolerate this pathogen, it may act as a carrier for spreading chytrid to the region when it is imported through commercial trade."

In another alarming discovery, the scientists found that all 497 frogs sampled from 23 frog farms in Vietnam had skin lesions ranging from swelling and inflammation to ulcers and deformed or missing digits in the most severe cases. Disease examination revealed four of the animals had bacteria associated with the lesions that in two cases appeared to have spread to other organs.

While the bacteria and its role as primary or secondary pathogen could not be positively identified, the scientists noted that frog farms could serve as a source of infection for the wider environment.

The study noted that lesions among frogs raised at commercial facilities in Vietnam are of particular concern, in light of the low level of bio-security that exists. All of the farms in the study disposed of untreated wastewater directly into natural watercourses, which becomes an avenue to spread infection to other places and other species.

According to the authors, the World Organization for Animal Health (OIE) requires its 174 member countries, which include the four countries in this study, to conduct surveillance for chytrid fungus, report confirmed cases, and implement measures to control their spread.

Co-author of the study, Assistant Professor David Bickford from the Department of Biological Sciences at the NUS Faculty of Science, said, "In light of the fact that this emerging infectious disease is now known to be spread by commercial trade, it is in everyone's best interest to eliminate it from the trade in live animals before both the native amphibian populations of Southeast Asia are affected and before it completely decimates the commercial trade and people are unable to make a living. This is not just about the frogs."

The paper concludes, "There is an urgent need to conduct wider surveys of wild amphibians in Southeast Asia to determine the extent and severity of chytrid fungus and other infectious diseases among a range of species, and whether and how these change over time. Studies should focus on differentiating Batrachochytrium dendrobatidis strains that may be endemic to the region from exotic strains that may be introduced through routes including international trade."

Liolaemus & Climate Change

Liolaemus tenuis in Maipo Canyon, Chile (near San Alfonso). Photo credit: Kaldari

The following pres release from the University of  Lincoln describes research on the genus Liolaemus, a clade of lizards restricted to southern South America.  It holds about 230 species, nine of which were described during 2012. Many of these lizards have adapted to high elevations and the long cold season associated with them. In the process, they have been able to switch their mode of reproduction from live-bearing to egg-laying many times. The forthcoming paper has been published early on-line and a link to the abstract is at the bottom of the page.

Climate change could lead to dozens of lizard species becoming extinct within the next 50 years, according to new research published this week.

Globally it has been observed that lizards with viviparous reproduction (retention of embryos within the mother’s body) are being threatened by changing weather patterns. A new study suggests that the evolution of this mode of reproduction, which is thought to be a key successful adaptation, could, in fact, be the species’ downfall under global warming.

Dr Daniel Pincheira-Donoso, from the School of Life Sciences at the University of Lincoln (UK), is the lead author of the paper detailing these amazing predictions, published in the scientific journal Global Ecology and Biogeography.

Researchers, including academics from the University of Exeter, investigated the hypothesis that historical invasions of cold climates by Liolaemus lizards – one of the most diverse groups of vertebrates on earth – have only been possible due to their evolution to viviparity (live birth) from oviparity (laying eggs). Remarkably, once these species evolve viviparity, the process is mostly irreversible and they remain restricted to colder climates.

By analysing this evolutionary transition in the lizards’ reproductive modes and projecting the future impact of climate change, the scientists discovered that increasing temperatures in the species’ historically cold habitats would result in their areas of distribution being significantly reduced. As a consequence, if global warming continues at the same rate, viviparous lizards are facing extinction in the next few decades.

Dr Daniel Pincheira-Donoso is one of the few people in the world who works on the ecology and evolution of these lizard species.

He said: “Lizards’ reproduction is largely linked to climatic temperatures and viviparous species are usually found in cold environments. When reptiles initially moved to colder areas they needed to evolve emergency measures to succeed in these harsh places, and we believe viviparity is one of these key measures. However, this transition is mostly one-directional and unlikely to be reversed. Rapid changes in the environment’s temperature would demand rapid re-adaptations to secure the species’ survival. Through the research we found that over the next 50 years nearly half of the area where these species occur may disappear, causing multiple extinction due to climate change.”

Overall the conclusion is that although viviparity allowed lizards in the past to invade and adapt to live in cold environments, and was therefore a key trait for evolutionary success, it will now ultimately lead to multiple events of extinction.

Dr Pincheira-Donoso said: “These lizards are one of the most diverse groups of animals, and are able to adapt to remarkably diverse conditions. Unfortunately, a reduction in cold environments will reduce their areas of existence, which means that their successful evolutionary history may turn into a double-edged sword of adaptation. Their extinction would be an atrocious loss to biodiversity.”

Dr Dave Hodgson, from the University of Exeter, said: “Climate change must not be underestimated as a threat to modern patterns of biodiversity. Our work shows that lizard species which birth live young instead of laying eggs are restricted to cold climates in South America: high in the Andes or towards the South Pole. As the climate warms, we predict that these special lizard species will be forced to move upwards and towards the pole, with an increased risk of extinction.”

Citation
Pincheira-Donoso, D., Tregenza, T., Witt, M.J. & Hodgson, D.J. The evolution of viviparity opens opportunities for a lizard radiation but drives it into a climatic cul-de-sac. Global Ecology and Biogeography, 2013