Wednesday, November 28, 2012

Tropical Lizard Adapts to Florida Winter

The Puerto Rican lizard Anolis cristatellus 
pictured above has adapted to the cooler winters 
of Miami. Credit: Manuel Leal, Duke.
DURHAM, NC - One tropical lizard's tolerance to cold is stiffer than scientists had suspected.

A new study shows that the Puerto Rican lizard Anolis cristatellus has adapted to the cooler winters of Miami. The results also suggest that this lizard may be able to tolerate temperature variations caused by climate change.

"We are not saying that climate change is not a problem for lizards. It is a major problem. However, these findings indicate that the thermal physiology of tropical lizards is more easily altered than previously proposed," said Duke biologist Manuel Leal, co-author of the study, which appears in the Dec. 6 issue of The American Naturalist.

Scientists previously proposed that because lizards were cold-blooded, they wouldn't be able to tolerate or adapt to cooler temperatures.

Humans, however, introduced Puerto Rican native A. cristatellus to Miami around 1975. In Miami, the average temperature is about 10 degrees Celsius cooler in winter than in Puerto Rico. The average summer temperatures are similar.

Leal and his graduate student Alex Gunderson captured A. cristatellus from Miami's Pinecrest area and also from northeastern Puerto Rico. They brought the animals back to their North Carolina lab, slid a thermometer in each lizard's cloaca and chilled the air to a series of cooler temperatures. The scientists then watched how easy it was for the lizards to right themselves after they had been flipped on their backs.

The lizards from Miami flipped themselves over in temperatures that were 3 degrees Celsius cooler than the lizards from Puerto Rico. Animals that flip over at lower temperatures have higher tolerances for cold temperatures, which is likely advantageous when air temperatures drop, Leal said.

"It is very easy for the lizards to flip themselves over when they are not cold or not over-heating. It becomes harder for them to flip over as they get colder, down to the point at which they are unable to do so," he said.

At that point, called the critical temperature minimum, the lizards aren't dead. They've just lost control of their coordination. "It is like a human that is suffering from hypothermia and is beginning to lose his or her balance or is not capable of walking. It is basically the same problem. The body temperature is too cold for muscles to work properly," he said.

Leal explained that a difference of 3 degrees Celsius is "relatively large and when we take into account that it has occurred in approximately 35 generations, it is even more impressive." Most evolutionary change happens on the time scale of a few hundred, thousands or millions of years. Thirty-five years is a time scale that happens during a human lifetime, so we can witness this evolutionary change, he said.

The lizards' cold tolerance also "provides a glimpse of hope for some tropical species," Leal added, cautioning that at present scientists don't know how quickly tolerance to high temperatures -- another important consequence of climate change -- can evolve.

He and Gunderson are now working on the heat-tolerance experiments, along with tests to study whether other lizard species can adjust to colder temperatures.

Citation

Manuel Leal, Alex R. Gunderson. Rapid Change in the Thermal Tolerance of a Tropical Lizard. The American Naturalist, 2012; 180 (6): 815 DOI: 10.1086/668077

European Fashion & the Python Trade


Nearly a half million python skins are exported each year - almost exclusively for use in European fashion - in a massive market with a legal value of more than $1.0 billion, according to the study Trade in South-East Asian Python Skins.

Many of the skins end up as designer handbags, belts, wallets and other accessories. Italy, Germany and France are the biggest importers, while most of the skins come from Indonesia, Malaysia and Vietnam.

The trade of python products is closely controlled by CITES, a UN-linked organisation charged with protecting the endangered species and other animals whose numbers are dwindling.

"Problems of illegality persist in the trade in python skins and... this can threaten the species' survival," Alexander Kasterine of the UN-linked International Trade Centre said in the report.

With supply chains often murky, a huge part of the snakeskin trade may be illegal and unsustainable, said the study, also backed by the International Union for the Conservation of Nature and the wildlife trade monitoring network TRAFFIC.

The extent of the illegal trade is hard to quantify, with many illegal skins going undetected. But the report found the illegal trade was possibly on a par with the legal trade.

Large numbers of wild pythons are slaughtered before they can reproduce, the report found, warning that many skins supposedly from captive-bred snakes were likely poached from the wild.

A lack of oversight meant quotas were easily ignored and illegal skins were being smuggled into shipments of legal items, it found.

The European fashion industry accounts for 96% of the value of the trade. It should push for more transparency in the supply chain, the study said, calling for a "traceability system" so consumers would know if their snakeskin product is from a legitimate source.

The report also recommended "legally binding minimum skin size limits to ensure protection of immature snakes."

Legislation to Regulate Importation of Constrictors


The following story is being carried by The Chattanoogan.com.

One of the country’s leading conservation groups wants Congress to ban imports of reticulated pythons, green anacondas, boa constrictors, and two other constrictor snakes that pose a major threat to native wildlife. In a letter sent the U.S. House Resource Committee, American Bird Conservancy says these snakes should be added to the list of “injurious wildlife” regulated by the Lacey Act, one of America’s oldest conservation statutes designed to protect wildlife from illegal trade. The change would make importing or transporting these snakes over state lines a federal offence.

“This bill (H.R. 511 –To Prohibit the Importation of Various Injurious Species of Constrictor Snakes) is necessary to prevent the further spread of these aggressive, invasive predators,” said Darin Schroeder, Vice President for Conservation Advocacy at ABC. “It’s well-established that these snakes are highly adaptable to new environments, and that they consume a wide variety of prey, including mammal, amphibian, lizard, and threatened and endangered bird species.”

Mr. Schroeder says fast-breeding and long-lived constrictor snakes have already done tremendous ecological damage in the state of Florida, where people who originally bought the snakes as pets have released them into the wild. The Burmese python, for example, is now estimated to have a breeding population in Florida in the tens of thousands. In a recent study, scientists collected more than 300 Burmese pythons in Everglades National Park and found that birds, from the five-inch-long House Wren to the four-foot-long Great Blue Heron, accounted for 25 percent of the python’s diet in the Everglades.

Mr. Schroeder adds that wildlife in the Hawaiian Islands could face similar devastation if constrictors or other snakes were to become established there. According to a 2001 study titled, Risk to Hawaii from Snakes by Fred Kraus and Domingo Carvalho, and published in the peer-reviewed journal Pacific Science, there was a yearly average of 24 snake sightings, mostly free-roaming animals that were not recovered, reported state wide between 1990 and 2000. For ABC, that concern is heightened by facts that most of the species recovered feed largely on birds, and by the fact that 70% of all native Hawaiian birds are already either listed as threatened or endangered or of conservation concern. More than one third of all bird species listed under the U.S. Endangered Species Act are Hawaiian.

“If snakes were to reproduce and proliferate, it quickly may be too late to stop them, and as a result, every measure to keep them out of places like Hawaii needs to be taken,” said Mr. Schroder in the letter. ”ABC strongly supports H.R. 511 and urges the full committee to take up and pass this important piece of legislation and send it to the floor of the House for full consideration.”

The best-known example of the damage a non-native snake can do can be found on the island of Guam, where the brown tree snake was accidentally introduced to from its native range of New Guinea and Australia after World War II. The problems caused by those invasive snakes were not limited to the near-total devastation of the island’s bird life: they also include major disruptions of electric power transmission, telephone service, military operations, computers, and tourism. Preying on eggs and birds alike, the brown tree snake has caused the extinction of nine of the eleven native land bird species on Guam.

Orsini Viper's Reproductive Strategy

A female Orsini's viper observed at the end of August 2011. 
This snake is gestating and will give birth to two offspring a
fortnight later. Credit: Thomas Tully. This image is available
 from the CNRS phototheque, phototheque@cnrs-bellevue.fr


Orsini's viper is a small insectivorous snake that is rare and extremely threatened in France. Since the early 1980s, a population of Orsini's vipers on Mont Ventoux has been the subject of an in-depth monitoring study. In total, 160 females were monitored throughout their lives, revealing that adult specimens (which can live for more than 12 years) regularly alternate between reproductive and non-reproductive years. A mathematical model confirmed that natural selection could induce alternation between reproductive years and years of growth. In this species, adult females reproduce every two years. In the non-reproductive years, snakes build up fat reserves and invest resources in body growth, which is possible throughout their lives and influences their fertility. The larger a female becomes, the more offspring she can produce. In a reproductive year, growth stops and all the acquired resources are committed to reproduction. This means that the reproductive success rate is high and that the immediate physiological impact on the mothers is low. This "strategy" differs radically from the behavior of other viviparous snake species, in which the females appear very thin after they have given birth. Their fat reserves 'melt away", which can threaten their survival. The strategy of Orsini's viper, however, allows a high quality litter to be born without such a "cost" to the parent. Monitoring females before and after reproduction to assess their condition, body growth and survival rate has shed light on the logic behind this particular reproductive behavior, which is not - as generally thought - correlated with environmental fluctuations. The findings of this research could explain many other cases of intermittent reproduction in other species of both animals and plants. They also illustrate the value of long-term individual studies on natural populations for improving knowledge of the ecological and physiological mechanisms that determine species demography.

Citation
Baron, J.-P., Le Galliard, J.-F., Ferrière, R., Tully, T. (2012), Intermittent breeding and the dynamics of resource allocation to reproduction, growth and survival. Functional Ecology. doi: 10.1111/1365-2435.12023

Migration Behavior in Giant Tortoises

While Galapagos giant tortoises move very slowly and at a leisurely pace,
they can nevertheless cover great distances. © MPI f. Ornithology
The Galapagos giant tortoise, one of the most fascinating species of the Galapagos archipelago, treks slowly and untiringly across the volcanic slopes. Scientists of the Max Planck Institute for Ornithology in Radolfzell, together with the Charles Darwin Foundation, have used GPS technology and modern 3D acceleration measurements to find out that especially the dominant male tortoise wanders up to 10 kilometers into the highlands of the island. Only the fully grown animals migrate, the young tortoises stay year round in the lowlands. The reason for this and the question of why the animals don't rest during the dry season are not known yet.

Even Charles Darwin anticipated that the giant tortoises wandered large distances. In the cool dry season, the highlands of Santa Cruz are engulfed in fog which allows the vegetation to grow despite the lack of rain. In the lowlands, however, there is no thick layer of clouds and the tortoises' vegetation is not available year round. Adults, which can weigh up to 250 kilogram, spend the dry season in the higher regions at an elevation of 400 meters above sea level. However, since the food is not as nutritious there, they trek back to the lower zones where there is succulent vegetation in abundance as soon as the rainy season begins.

In order to study the migratory pattern more closely, Stephen Blake from the Max Planck Institute for Ornithology and his colleague Washington Tapia from the Galapagos National Park secured GPS loggers with 3D acceleration monitors onto 17 adult tortoises. This allowed the scientists to determine the animals' exact position and behavior over a period of two years. In order to gather information on the entire population, the researchers noted the size, sex and location of each tortoise they met on their monthly hikes along the volcanic hillsides. They combined the GPS data with the temperature data and information about availability of vegetation.

The results show that the tortoises have a partial migration system, where not every individual migrates. Only the adult animals wander and only the larger specimens are more likely to move. In June they start their slow, tedious march which can be up to ten kilometers long into the highlands. Adult females remain in the lowlands until they lay their eggs and then they also make their way to the highlands. In contrast, the smaller tortoises stay in the lower elevated areas all year round.

Although giant tortoises are able to survive for up to one year without nourishment, which made them a popular staple for seamen, they nevertheless wander for large distances searching for food as this study shows for the first time. Why don’t they just look for a shelter? The question of why the younger animals don’t migrate hasn’t been answered by the scientists yet. “Either the energy expenditure of this strenuous hike is too high, or there is still enough food available for the smaller animals.” Stephen Blake suspects, “perhaps the younger animals can’t tolerate the wet cold climate of the higher regions.”

In other species, the largest and the most dominant individual does not migrate because it can best defend itself against its competitors. It doesn’t have to leave to survive. However, among the Galapagos tortoises, it’s usually the largest and most dominant individual which takes on this arduous journey.

Future studies on giant tortoise species of the other Galapagos Islands with varying ecological conditions will show how environment influences the migration scheme of these closely related reptiles. The scientists also want to include factors such as age, size, sex and morphology in their studies to see why the behavior changes in different lifetime stages and what the trigger of migration is.

Despite the threat of hunting, invasive species such as goats and rats, and the loss of habitat due to man, the Galapagos Tortoise still shows its original migrating behavior. This and future studies will help to maintain this behavior with the help of effective measures such as establishing corridors, preserving key habitats, keeping tortoise-friendly roads and maintaining less urban development. Based on its importance to the Galapagos Archipelago ecosystem as an herbivore and seed disperser, the annual migration of the tortoise must be preserved. Article available on-line.

A New Blunt-headed Treesnake from Ecuador

Imantodes chocoensis
Blunt-headed tree snakes range from Mexico and Argentina, and are distinct from all other New World snakes because they have an exceptionally thin body, slender neck, big eyes, and a blunt head. The arboreal snakes hunt frogs and lizards at night and their extremely gracile bodies allow them to bridge gaps between branches that most other arboreal snakes cannot. Omar Torres-Carvajal from Museo de Zoología QCAZ and colleagues (2012) have described Imantodes chocoensis, in the journal Zookeys bringing the number of species in the genus to seven. The Chocoan blunt-headed tree snake chocoensis inhabits the Chocoan forests of northwestern Ecuador. DNA data also suggest that I. chocoensis’ closest relative is a species that inhabits the Amazon on the other side of the Andes.

“One possible explanation for the disjunct distribution between the new species and its closest relative is that the uplift of the Andes fragmented an ancestral population into two, each of which evolved into a different species, one in the Chocó region and the other in the Amazon,” Omar Torres-Carvajal from Museo de Zoología QCAZ, who led the study, said in a statement.

Snakes collected as far back as 1994, and deposited in several Ecuadorian and American natural history museums were examined for the study to help determine whether this was a newly discovered species.

The head of the chocoensis is about the size of a penny, and the species slightly exceeds a meter in total length. The Chocoan forests are part of the Tumbes-Chocó-Magdalena hotspot that lies west of the Andes. The full article is available on-line.

Citation
Omar Torres-Carvajal, Mario H. Yánez-Muñoz, Diego Quirol, Eric N. Smith, & Ana Almendáriz. 2012. A new species of blunt-headed vine snake (Colubridae, Imantodes) from the Chocó region of Ecuador. ZooKeys 244: 91–110, doi: 10.3897/zookeys.244.3950

Monday, November 26, 2012

Hybrid Salamander Larvae Survive Pesticides

Three types of salamander larvae: native California tiger salamanders 
(Ambystoma californiense), barred tiger salamanders (Ambystoma tigrinum 
mavortium), and the hybrid offspring born when the two species mated. 

Photo Credit: Bruce Delgado, U.S. Bureau of Land Management.

Hybridization among ambystomid salamander species is common. Ambystoma tigrinum mavortum, the barred tiger salamander may have been introduced into California from released pets, or as fishing bait imported from the upper midwest. Whatever their origin, they have bred with the endemic California tiger salamander, Ambystoma californiense, a situation that has been well known for a number of years. In a new study Ryan et al (2012) find that in the intensively farmed Salinas Valley, California, the threatened California tiger salamanders (Ambystoma californiense) have been replaced by hybrids between California tiger salamander and introduced barred tiger salamanders (Ambystoma tigrinum mavortium).The authors conducted an enclosure experiment to examine the effects habitat modification and relative frequency of hybrid and native California tiger salamanders have on recruitment of salamanders and their prey, the Pacific chorus frogs (Pseudacris regilla). They tested whether recruitment differed among genetic classes of tiger salamanders (hybrid or native) and pond hydroperiod (seasonal or perennial). Roughly six weeks into the experiment, 70% of salamander larvae died in four out of six ponds. Native salamanders survived (n = 12) in these ponds only if they had metamorphosed prior to the die-offs. During die-offs, all larvae of native salamanders died, whereas 56% of hybrid larvae died. The authors necropsied native and hybrid salamanders, tested water quality, and queried the California Department of Pesticide Regulation database to investigate possible causes of the die-offs. Salamander die-offs, changes in the abundance of other community members (invertebrates, algae, and cyanobacteria), shifts in salamander sex ratio, and patterns of pesticide application in adjacent fields suggest that pesticide use may have contributed to die-offs. That all survivors were hybrids suggests that environmental stress may promote rapid displacement of native genotypes.

RYAN, M. E., JOHNSON, J. R., FITZPATRICK, B. M., LOWENSTINE, L. J., PICCO, A. M. and SHAFFER, H. B. (2012), Lethal Effects of Water Quality on Threatened California Salamanders but Not on Co-Occurring Hybrid Salamanders. Conservation Biology. doi: 10.1111/j.1523-1739.2012.01955.x

Saturday, November 24, 2012

Squamate Body Elongation & Climate

Gymnopthalmus underwoodi, a species not included in this study.

The evolution of elongated body shapes in squamate vertebrates has intrigued biologists for decades. Grizante et al. (2012) suggest several factors may explain how the environment influences the evolution of body elongation, and note climate needs to be incorporated in this scenario to evaluate how it contributes to morphological evolution. Climatic parameters include temperature and precipitation, two variables that likely influence environmental characteristics, including soil texture and substrate coverage, which may define the selective pressures acting during the evolution of morphology. GIS (geographic information system) techniques are now available and can now be included in evolutionary biology studies. Grizante et al used GIS in present study to test for associations between variation in body shape and climate in the tropical lizard family Gymnophthalmidae. They first investigated how the morphological traits that define body shape are correlated in these lizards and then tested for associations between a descriptor of body elongation and climate. Their analyses revealed that the evolution of body elongation in Gymnophthalmidae involved concomitant changes in different morphological traits: trunk elongation was coupled with limb shortening and a reduction in body diameter, and the gradual variation along this axis was illustrated by less-elongated morphologies exhibiting shorter trunks and longer limbs. The variation identified in Gymnophthalmidae body shape was associated with climate, with the species from more arid environments usually being more elongated. Aridity is associated with high temperatures and low precipitation, which affect additional environmental features, including the habitat structure. This feature may influence the evolution of body shape because contrasting environments likely impose distinct demands for organismal performance in several activities, such as locomotion and thermoregulation. The authors establishes a connection between morphology and a broader natural component, climate, and introduces new questions about the spatial distribution of morphological variation among squamates.

Grizante MB, Brandt R, Kohlsdorf T (2012) Evolution of Body Elongation in Gymnophthalmid Lizards: Relationships with Climate. PLoS ONE 7(11): e49772. doi:10.1371/journal.pone.0049772

New Report of a Rare Bothrops

Murici Lancehead, Photo Frank Stemitz

Bothrops muriciensis was described more than a decade ago by Ferrarezi & Freire (2001) from Brazil's Atlantic Forest on the basis of three specimens. Freitas et al.(2012) report on six more specimens collected in the Murici region of Alagoas, Brazil. They increase the number of localities the snake has been found at, note that it is terrestrial, and found about 400 m in elevation. And, they suggest the IUCN should consider the species Critically Endangered. Its survival is probably dependent on the Murici Ecological Station, while the forest around it is being removed. The new specimens records include juveniles and adults that were close to streams. The full article can be found on-line.

Citation
Freitas, M. A. et al. 2012. Notes on the conservation status, geographic distribution and ecology of Bothrops muriciensis Ferrarezzi & Freire, 2001 (Serpentes, Viperidae).  NORTH-WESTERN JOURNAL OF ZOOLOGY 8 (2): 338-343.



Friday, November 23, 2012

Herps of the Tucker Valley Bioblitz


The first BioBlitz in Trinidad and Tobago was held in Tucker Valley in Chaguaramas on November 17 & 18. The idea behind a BioBlitz is to identify as many species as possible in a chosen area within 24 hours, provided science with some information and raise awareness of biodiversity within the general public. Tucker Valley includes a variety of forest types and has an adjacent marine environment that includes a coral reef and sea grass beds. Tucker Valley was chosen as the site for the country's first-ever BioBlitz because of its wide range of habitats, including four different types of forest, freshwater rivers and streams; seagrass beds at the southern end in Williams Bay; and coral reef at the northern end in Macqueripe Bay.
The event was well attended by the general public and media.
Mike Rutherford at work.
Probably the second most likely frog species to be found
 the tungara frog, Engystomops pustulosus.

The least likely snake to be found, Lachesis muta.
Forty-one species of herps (frogs, turtles, lizards, and snakes) had been previously reported from the valley, so how many could be found in 24 hours? My unofficial count was 25 species  (10 frogs, 1 turtle, 1 crocodilian, 8 lizards, and 5 snakes) or about 61% of the known fauna. Perhaps the biggest surprise was a 2 meter bushmaster found DOR by the birding group. Lachesis muta had not been previously reported from the valley.

Saturday, November 10, 2012

Steroids & Temperature Influence Sex Determination in Gekko japonicus


Sex determination is a developmental process altering undifferentiated gonads into testes or ovaries. Vertebrates have two types of sex determination: genotypic sex determination (GSD), in which offspring sex is determined at the time of fertilization by genetic factors and environmental sex determination (ESD), where environmental factors act after fertilization at a critical time in embryonic development to determine offspring sex. 

Temperature dependent sex determination (TSD) is one form of ESD. TSD is widespread in reptiles including all crocodilians, tuataras, many turtles and some lizards. The discovery that in TSD species temperature is not the only factor influencing sex determination suggests that other factors, especially maternal influences via yolk steroid hormone deposition, can influence the end result of the sexual differentiation process, although the influence (direction and/or magnitude) of a given steroid hormone may be species-specific. For example, eggs with elevated levels of corticosterone are more likely to produce daughters in the Jacky dragon, Amphibolurus muricatus, and sons in the three-lined skink, Bassiana duperreyi.

Ding et al. (2012) incubated eggs of the Japanese gecko Gekko japonicus at three temperatures, and measured yolk testosterone (T) and 17β-estradiol (E2) levels at three time points in embryonic development (oviposition, 1/3 of incubation, and 2/3 of incubation), to examine whether maternal influence on offspring sex via yolk steroid hormone deposition is significant in the species. Eggs incubated at 24 °C and 32 °C produced mostly females, and eggs incubated at 28 °C almost a 50:50 sex ratio of hatchlings. Female-producing eggs were larger than male-producing eggs. Clutches in which eggs were incubated at the same temperature produced mostly same-sex siblings. Yolk T level at laying was negatively related to eggs mass, and yolk E2/T ratio was positively related to egg mass. Their data in G. japonicus show that maternal influence on offspring sex via yolk steroid hormone deposition is significant; incubation temperature affects the dynamics of developmental changes in yolk steroid hormones; influences of yolk steroid hormones on offspring sex are secondary relative to incubation temperature effects; and offspring sex correlates with an interaction between incubation temperature and yolk steroid hormones.

Citation
Ding G-H, Yang J,  Wang J, Ji X. 2012. Offspring sex in a TSD gecko correlates with an interaction between incubation temperature and yolk steroid hormones. Naturwissenschaften 1-8, 

Friday, November 9, 2012

Sensitive Crocodilians

Scanning electron microscope image of the jaws of a crocodile clearly show the
 sensory spots dotting its skin. (Courtesy of the Catania Lab)
Crocodiles and alligators are notorious for their thick skin and well-armored bodies. So it comes as something of a surprise to learn that their sense of touch is one of the most acute in the animal kingdom.

The crocodilian sense of touch is concentrated in a series of small, pigmented domes that dot their skin all over their body. In alligators, the spots are concentrated around their face and jaws.

A new study, published in the Nov. 8 issue of the Journal of Experimental Biology, has discovered that these spots contain a concentrated collection of touch sensors that make them even more sensitive to pressure and vibration than human fingertips.

“We didn’t expect these spots to be so sensitive because the animals are so heavily armored,” said Duncan Leitch, the graduate student who performed the studies under the supervision of Ken Catania, Stevenson Professor of Biological Sciences at Vanderbilt.

Scientists who have studied crocodiles and alligators have taken note of these spots,which they have labeled “integumentary sensor organs” or ISOs. Over the years they have advanced a variety of different hypotheses about their possible function. These include: source of oily secretions that keep the animals clean; detection of electric fields; detection of magnetic fields; detection of water salinity; and, detection of pressure and vibrations.

In 2002, a biologist at the University of Maryland reported that alligators in a darkened aquarium turned to face the location of single droplets of water even when their hearing was disrupted by white noise. She concluded that the sensor spots on their faces allowed them to detect the tiny ripples that the droplets produced.

“This intriguing finding inspired us to look further,” Catania said. “For a variety of reasons, including the way that the spots are distributed around their body, we thought that the ISOs might be more than water ripple sensors.”

As a result, Leitch began a detailed investigation of the ISOs and their neural connections in both American alligators and Nile crocodiles. Leitch found that these sensory spots are connected to the brain through the trigeminal ganglia, the nerve bundle that provides sensation to the face and jaw in humans.

In addition, his studies ruled out most of the alternative hypothesis for the ISOs function. For example, his anatomical studies didn’t find pores that could release cleansing oil. Similarly, he found that the nerves in the ISOs didn’t react to electric fields or, when submerged in water, to changes in salinity.

“I didn’t test for sensitivity to magnetic fields, but we don’t think this is likely either,” said Leitch. In animals that can detect magnetic fields, he explained, the sensors are located inside the body, not on the surface.

What he did find is a diverse collection of “mechanoreceptors:” nerves that respond to pressure and vibration. Some are specially tuned to vibrations in the 20-35 Hertz range, just right for detecting tiny water ripples. Others respond to levels of pressure that are too faint f Their analysis led the scientists to conclude that the crocodilian’s touch system is exceptional, allowing them to not only detect water movements created by swimming prey, but also to determine the location of prey through direct contact for a rapid and direct strike and to discriminate and manipulate objects in their jaws.

Their finding that the most heavily wired ISOs are located in the mouth near the teeth suggests that the touch sensors help the animals identify the objects that they catch in their jaws. The sensors also appear to provide the sensitivity that female alligators and crocodiles need to delicately break open their eggs when they are ready to hatch and to protect their hatchlings by carrying them in their jaws, the same jaws that can clamp down on prey with a force of more than 2,000 psi.

Citation
Leitch D.B. & Catania, K.C. 2012. Structure, innervation and response properties of integumentary sensory organs in crocodilians. Journal of Experimental Biology, DOI: 10.1242/%u200Bjeb.076836

Sunday, November 4, 2012

London's Exotic Herpetofauna

Zamenis longissimus. Photo credit: Felix Reimann

The following article is from the Independent by Michael McCarthy.

A large rat-eating snake from Europe is breeding in central London – just one of more than 50 foreign reptiles and amphibians seen living wild in the capital area in recent years.

At up to 6 ft 6 ins long, the predatory Aesculapian snake, which feeds on rats and other small mammals, is bigger than any native British reptile, but although it is found across the continent from France to Russia, it has never been a resident of Britain.

Yet now a small population of Zamenis longissimus is flourishing in London NW1, a stone's throw – or a snake's slither – from one of the capital's smartest addresses, Primrose Hill.

There are thought to be 30 or more of the snakes, descendants of a small group released in the 1980s, living and breeding in the undergrowth alongside the Regent's Canal at the edge of Regent's Park, near London Zoo. But the actors, media types and rock musicians of Primrose Hill can take comfort in the fact that although their new neighbours are big, they are not venomous.

They are one of many exotic and non-native presences from the reptile and amphibian world which have been recorded living wild within the Greater London area – roughly the area inside the M25 – according to a detailed report from the London Natural History Society, which is featured in the current issue of British Wildlife magazine.

No fewer than 51 alien taxa – the technical term for species and sub-species counted together – have been observed, split between 30 reptiles, ranging from snapping turtles to red-eared terrapins, and 21 amphibians, from American bullfrogs to midwife toads.

In particular, there are no fewer than 22 different types of freshwater terrapin – mostly American species and hybrids – at large in park ponds and lakes and rivers in probably every London borough, originating from a pet craze which followed the American animated children's TV series Teenage Mutant Ninja Turtles of the late 1980s and early 1990s.

"On the back of the TV programme the North American terrapin became the latter-day hamster," said Tom Langton, a conservation ecologist who is one of the authors of the report.

"It was a cool pet. But people didn't realise that these animals grow slowly and can live up to 50 or 60 years, not the six months to two years when I can remember my hamsters dying.

"The majority of these animals were dumped when people could no longer cope with them. Teenagers leaving home left a trail of terrapins to be put in the local river or the local park."

The second biggest group are several species of "green" or "water" frogs from Europe, including the marsh frog, the pool frog and the edible frog, which Mr Langton said had been spread "massively" by the pet trade. They presented a potential threat of disease, he said.

Amphibians all over the world are being affected by diseases, especially the deadly chytrid fungus, which was found in American bullfrogs in Kent, until they were eradicated, said Mr Langton.

As for the Aesculapian snakes, which are named after Asclepius [sic], the Greek god of medicine, he said: "It's a fascinating story. They are iconic animals and were on Roman coins as a symbol of healing.

"People will take snakes the wrong way and they'll think, Oh God … but they're not venomous and they're lovely animals, actually, if you get a chance to sit and watch them.

"It's unreal that they're in the UK."

Saturday, November 3, 2012

A new sphenodontid beakhead from the late Jurassic

The extant tuatara, Sphenodon punctatus

Rhynchocephalians (beakheads) form the sister group to the squamates (lizards and snakes) and are represented by the extant single genus Sphenodon (the tuataras) today. Beakheads are often considered to represent a very conservative lineage. However, rhynchocephalians were common from the late Triassic to late Jurassic, but the clade went into rapidly declined afterwards, a decline frequently attributed to the supposedly adaptive inferiority of the beakheads to squamates and  Mesozoic mammals, which radiated at that time.

Rauhut et al. (2012) report a new fossil rhynchocephalian from the late Jurassic of southern Germany, teeth of this new animal  consists of massive, continuously growing plates, suggesting a device for crushing food, a previously unknown feeding adaptation in rhynchocephalians.

The evolution of the extraordinary dentition of Oenosaurus from the already highly specialized Zahnanlage generally present in derived rhynchocephalians demonstrates an unexpected evolutionary plasticity of these animals. Together with other lines of evidence, this seriously casts doubts on the assumption that rhynchocephalians are a conservative and adaptively inferior lineage. Furthermore, the new taxon underlines the high morphological and ecological diversity of rhynchocephalians in the latest Jurassic of Europe, just before the decline of this lineage on this continent. Thus, selection pressure by radiating squamates or Mesozoic mammals alone might not be sufficient to explain the demise of the clade in the Late Mesozoic, and climate change in the course of the fragmentation of the supercontinent of Pangaea might have played a major role.

Roland Pöschl, found the 146 million year old fossil, and the owners and operators of the Krautworst Naturstein quarry, Ulrich Leonhardt, Roland Pöschl and Uwe Krautworst, donated the specimen to the Staatssammlung für Paläontologie und Geologie in Munich.

Citation
Rauhut OWM, Heyng AM, López-Arbarello A, Hecker A (2012) A New Rhynchocephalian from the Late Jurassic of Germany with a Dentition That Is Unique amongst Tetrapods. PLoS ONE, 7(10): e46839. doi:10.1371/journal.pone.0046839

Thursday, November 1, 2012

Suzio Report- Recent Additions to the Kilometer Club

Happy Halloween Herpers, 10/31/12

We'll let the images do the talking:

Image 1: CM12, Site 25: This is our world traveling, big, bad male molossus. Between August 8 and August 24--he bombed westward, and then back eastward. Total distance moved: 1,968 meters. He was only 33 meters off traveling in straight  west-east trajectory! I couldn't follow a compass and stay that straight of a course.


This image was taken last weekend. He is now on the south-center slope of Iron Mine Hill (IMH).

Image 2: CM14_View: This image was taken looking down Tim Canyon, the first major drainage to the north from the southwest edge of the Suizo Mountains proper. He has been tracked all the way from the south bajada of IMH to this particular location. Total distance traveled: 1,214 meters. IMH can't even be seen in the image.


Now, while you're looking at that image, cast your eyes to the tallest hill on the left. At the base of that
hill we found CT14 on October 6. See image 3:

Image 3: CT14, AKA "Rhino K12" in situ. Between 6 October and 21 October, he earned the "K12"
part of his name by bombing over 1200 meters northward, gaining 120 meters in elevation in the process.
Image 4 shows his current location:


Image 4, by Marty Feldner: This is what those of us involved with the Suizo Mountain Study call "WAY
IN THE F*CK UP THERE." Note John's truck parked at the bottom, as well as the dangerous footwork involved on the part of John Slone required to pinpoint K12's location.
This tiger has traveled more upslope and further north than any other herp in our 11.5 year study! He's a big and beautiful male, and a large move was expected. But this is off the charts!

As we now approach the time where visuals will get scarce, my next report will deal with our last looks of all
the animals under watch. Stay tuned.
Best to all, roger