Sunday, September 28, 2014

New genera of homalopsid snakes

Until recently these two snakes were both in the genus Enhydris.
Both are adults, both have smooth scales and their internasals in
contact. Yet they have different ancestors within the family 
homalopsidae as suggested by their dramatically different body 
shapes. JCM
The colubroid snake family Homalopsidae also known as the Australasian rear-fanged water snakes contained 10 genera and 34 species of rear-fanged semi-aquatic and aquatic snakes in 1970 with the publication of Ko Ko Gyi’s monograph. In 2007 Murphy updated Gyi’s work and the family held the same 10 genera with 37 species plus two genera of uncertain status (Anoplohydrus, Brachyorrhos). Molecular studies published in the first decade of the 21st century demonstrated that while the Homalopsidae is monophyletic, the species-rich genus Enhydris is polyphyletic. Molecular analysis also found Brachyorrhos to be the most basal member of the clade, confirming an earlier hypothesis that it was a fangless homalopsid. Subsequently, two other fangless genera (Calamophis and Karnsophis) of homalopsids were discovered.

In a newly published paper Murphy and Voris (2014) revalidate the genera for the polyphyletic genus Enhydris: Homalophis Peters, Hypsiscopus Fitzinger, Miralia Reuss, Phytolopsis Gray, and Raclitia Gray. They also describe five new genera for species lacking available names: Gyiophis, Kualatahan, Mintonophis, Sumatranus, and Subsessor. The new arrangement for homalopsid names resolves the problem of the formerly polyphyletic genus Enhydris. See tree below.

Gyi (as well as Boulenger and Gunther) placed snakes in the genus Enhydris because they shared smooth dorsal scales and internasals that were in contact. These characters do not necessarily suggest ancestry and many other traits seen in these snakes in fact suggested they were not closely related. Consider the small headed, gracile Enhydris enhydris and the largest known homalopsid, Subsessor (formerly Enhydris) bocourti with a massive body and head (see photo). Placing these snakes in the same genus implies they share a close common ancestor, a hypothesis not supported by morphology or DNA.

With this checklist the family now contains 53 species in 28 genera. Molecular studies suggest homalopsids are old, perhaps separating from their most recent common ancestor with the Lamprophiidae 53 million years ago.

Red lines indicate species considered Enhydris by Gyi. Names at the end of the red lines are current genera.
Recent evidence suggests homalopsids show high levels of endemism and cryptic speciation so it is likely that many more species, and likely more genera will be discovered in the future.

CitationMurphy JC and Voris HK. 2014. A Checklist and key to the homalopsid snakes (Reptilia, Squamata, Serpentes), with the description of new genera. Fieldiana Life and Earth Sciences 8:1-43. doi: http://dx.doi.org/10.3158/2158-5520-14.8.1

A new high altitude pit viper from Sumatra

Top. Trimeresurus gunaleni. Below its habitat
Vogel et al. (2014) investigated morphological variation in 126 specimens from at least 67 populations of Trimeresurus sumatranus. They found two distinct taxa: Trimeresurus sumatranus (Raffles) and Trimeresurus gunaleni sp. nov. They selected a neotype for Trimeresurus sumatranus and restricted its type locality to the vicinity of Bengkulu, Bengkulu Province, Sumatra. The second taxon Trimeresurus gunaleni represents a distinct, previously unnamed species. The holotype of Trimeresurus gunaleni is from Mt. Sibayak, ca. 1,500–2,200 m ASL, west of Brastagi (Berastagi), Karo Regency (Kabupaten Karo), Sumatera Utara Province, Sumatra, Indonesia. The new species differs from Trimeresurus sumatranus by a lower number of ventrals in males (162–179 against 178–185) and females (164–171 vs. 175–191); a distinctly longer tail in males; the also differ in the color of the tail, the color of the eyes: (green in the new species, vs. dark grey in T. sumatranus), the color of the ventrals, which are green with a pale posterior suture in the new species and pale with dark posterior suture in T. sumatranus. The new species Trimeresurus gunaleni lives at higher elevations than T. sumatranus and seems to be endemic to the higher mountain ranges of western Sumatra and inhabits regions typically covered with tropical moist montane forests, from 1,500 m to as high as at least 2,000 m, perhaps as much as 2,200 m, where it has been observed by local insect collectors. There is no record of popu­lations lower than 1,500 m. On Mount Sibayak, Trimeresurus hageni occurs at elevation of 500 m, and Tropidolaemus wagleri at 200 m. Trimeresurus gunaleni is clearly isolated as a high mon­tane dweller. The female holotype of T. gunaleni was collected during the daytime in dense humid montane for­est scattered with tiny springs. The snake was resting on the ground under tree roots. In another instance, a male was seen perched at night on a tree branch about two meters above the ground. None of the specimens were found.

Citation.

Vogle G, David P, Sidik I. (2014) On Trimeresurus sumatranus (Raffles, 1822), with the designation of a neotype and the description of a new species of pitviper from Sumatra (Squamata: Viperidae: Crotalinae). Amphibian & Reptile Conservation 8(2): 1–29.

Saturday, September 27, 2014

Gene duplication and the evolution of snake venom toxins


Gene duplication is a rare event in eukaryotic genomes and has been suggested as the major source of novel genetic material. Estimates of the rate of gene duplication in vertebrates vary from 1 gene per 100 to 1 gene per 1000 per million years and the most common fate for a duplicate gene is the loss of its function. However, in some cases a duplicate gene is retained in the population and undergoes either subfunctionalisation (where the two duplicates divide the sum of the ancestral role(s) between them) or neofunctionalisation (where one of the duplicates assumes a new role, independent of the ancestral function). This latter process of evolving an entirely new function is known to be incredibly rare and there are few conclusive examples of it in the literature.

The venom of advanced snakes has been hypothesized to have originated and diversified via gene duplication. Specifically, it has been suggested that both the origin of venom and the later evolution of novelty in venom has occurred as a result of the duplication of a gene encoding a non-venom physiological or “body” protein that is subsequently recruited, via gene regulatory changes, into the venom gland, where natural selection can act on randomly occurring mutations to develop and/or increase toxicity. In short, it has been proposed that snake venom diversifies via repeated gene duplication and neofunctionalisation, a somewhat surprising finding given the apparent rarity of both of these events.

Therefore, the hypothesis concerning the evolution of snake venom is very unlikely and should be regarded with caution, it is nonetheless often assumed to be established fact, hindering research into the true origins of snake venom toxins. To critically evaluate this hypothesis Hargreaves et al. (2014) generated transcriptomic data for body tissues and salivary and venom glands from five species of venomous and non-venomous reptiles. The comparative transcriptomic analysis of these data reveals that snake venom does not evolve via the hypothesized process of duplication and recruitment of genes encoding body proteins. Instead the results show that many proposed venom toxins are in fact expressed in a wide variety of body tissues, including the salivary gland of non-venomous reptiles and that these genes have therefore been restricted to the venom gland following duplication, not recruited. Thus snake, venom evolves via the duplication and subfunctionalisation of genes encoding existing salivary proteins. These results highlight the danger of the elegant and intuitive “just-so story” in evolutionary biology


Citation
Hargreaves AD, Swain MT, Hegarty MJ, Logan DW,  Mulley JF. 2014.  Restriction and recruitment – gene duplication and the origin and evolution of snake venom toxins. Genome Biology and Evolution Advance Access10.1093/gbe/evu166.


Thursday, September 25, 2014

A new burrow-using, fanged frog from Sarawak


Limnonectes cintalubang, new species (KUHE 47859)
Borneo is famous for its diverse endemic amphibians and the diversity can be expected to increase with the discovery of cryptic taxa. Frogs of the Limmnoectes kuhlii complex have enlarged head with fang-like processes on lower jaw in males, thus they are commonly called fanged frogs. Usually they have a brown dorsum covered by tubercles in variying degrees, and inhabit mountain streams at various altitudes. Limnonectes kuhlii was once considered a wide-ranging species, but is now regarded as a complex of many distinct species that are phylogenetically remote from Javanese L. kuhlii (Tschudi, 1838). Several continental populations have been described as distinct species, studies of Bornean populations have been lacking. Matsui et al. (2014) report finding a new species of this clade during a  recent amphibian survey in Serian, southwestern Sarawak. The frog has a unique coloration, escape behavior, and an unusual natural history.

The new species, Limnonectes cintalubang is subterranean and all specimens were found at night near burrows on the forest floor. When disturbed they immediately disappeared down the burrow. However, they do not seem to dig the hole by themselves, instead they use burrows constructed by other animals. What species dig the burrows used by this frog is unknown.  The skin of the species is exceptionally fragile and tears easily when captured. The eggs of L. cintalubang are creamy white unlike other congeners. Among Bornean frogs creamy white eggs without dark animal hemisphere are known in several  genera and all of them breed in deep shaded microhabitats such as small underground streams, in mud, and under leaf litter on the bottom of deep pools. The authors hypothesize that, L. cintalubang lays its eggs shaded localities, possible in water in the burrows.

Limnonectes cintalubang was found in loose slopes of secondary forests with mixed bamboo and broad-leaf trees, always on the ground. The surface of the ground is flat and sparsely covered by dead leaves, but with plant roots and stones densely packing the shallow layers under the soil surface. Frogs were active after 1930 h and each stayed near a burrow up to ca. 5–10 cm in diameter with a long tunnel at a depth of 50–60 cm, it was impossible to dig out the frog. Although only one of about 20 burrows observed had underground water, there was no pool at the immediate vicinity of the holes. The nearest water body was a stream ca. 8–12 m apart from the area. Males did not call in March, July, or December at the type locality. However, females collected in early July possessed large ovarian eggs, the breeding season is thought to include summer seasons. Other species found in association with the present new species in the forest were: Leptolalax gracilis (Günther, 1872), Leptolalax sp., Meristogenys jerboa (Günther, 1872), Nyctixalus pictus (Peters, 1871), and Polypedates leucomystax (Gravenhorst, 1829).


Citation
Matsui, M., Nishikawa, K., & Eto, K. (2014). A new burrow-utilising fanged frog from Sarawak, East Malaysia (Anura: Dicroglossidae). RAFFLES BULLETIN OF ZOOLOGY, 62, 679-687.

A phylogeny of snake combat and mating behaviors

A small study suggests snakes may have developed courtship and male-to-male combat behavior, such as moving undulations, neck biting, and spur-poking, over time, according to a study published September 24, 2014 in the open-access journal PLOS ONE by Phil Senter from Fayetteville State University and colleagues.

Behaviors involved in courtship and male-to-male combat have been recorded in over 70 snake species from five families in the clade Boidae and Colubroidea, but before now, scientists had yet to look for evolutionary relationships between these behaviors.

The authors of this study analyzed 33 courtship and male-to-male combat behaviors in the scientific literature by plotting them to a phylogenetic tree to identify patterns. The authors identified the patterns in behaviors, which was not always possible, and then used the fossil record to match the behaviors to the snakes' evolution.

Researchers found that male-to-male combat of common ancestors of Boidae and Colubridae in the Late Cretaceous likely involved combatants raising the head and neck, attempting to topple each other. Poking with spurs may have been added in the Boidae clade. In the Lampropeltini clade, the toppling behavior was replaced by coiling without neck-raising, and body-bridging was added. Snake courtship likely involved rubbing with spurs in Boidae.

In Colubroidea, courtship ancestrally involved chin-rubbing and head- or body-jerking. Various colubroid clades subsequently added other behaviors, like moving undulations in Natricinae and Lampropeltini, coital neck biting in the Eurasian ratsnake clade, and tail quivering in Pantherophis. Although many gaps in the evolution of courtship and combat in snakes remain, this study provides a first step in reconstructing the evolution of these behaviors in snakes.

Figure 3 from the paper with rattlesnake combat photos added. Scenario for the evolution of male-male combat behavior in snakes, based on data presented in Figure 1 in the paper. On the far right photos of Crotalus atrox in combat. Photo credit: Roger Repp.

Citation
Senter P, Harris SM, Danielle Kent DL. Phylogeny of Courtship and Male-Male Combat Behavior in Snakes. PLoS ONE, 2014; 9 (9): e107528 DOI: 10.1371/journal.pone.0107528


Wednesday, September 24, 2014

Cosumnes River Preserve restoration to protect Thamnophis gigas

The restored marsh and Thamnophis gigas. Photo credit CDFW
The California Department of Fish and Wildlife (CDFW) has completed an emergency restoration project at the Cosumnes River Preserve to help save a state and federal threatened species, the giant garter snake (Thamnophis gigas).

Snake Marsh at the Cosumnes River Preserve is home to a genetically unique population of giant garter snakes. With two consecutive years of drought, there was a significant chance of the marsh ponds drying up, potentially causing severe impacts to the snakes.

“The project consisted of well water being pumped into the marsh and the ponds where the snakes live. It was planned and carried-out on CDFW land that is part of the Preserve,” said CDFW Environmental Scientist Eric Kleinfelter. “We had very dedicated contractors and department staff who completed this project in just one month. The Nature Conservancy also played an important role by funding a hydrologic study that showed just how vulnerable to drought this aquatic system is. It was truly a collaborative effort.”

Endemic to California’s Central Valley, the non-venomous giant garter snake is olive to black in color with light yellowish stripes on each side and can grow from three to five feet long. Secretive and difficult to find, this aquatic snake will quickly drop into the water from its basking site before the observer can get close. When threatened, it will excrete a foul-smelling musk. It feeds primarily on fish, frogs and tadpoles and can live up to 12 years.

Located approximately 25 miles south of Sacramento near Galt, the Cosumnes River Preserve consists of approximately 48,000 acres of wildlife habitat and agricultural lands. The Preserve is buffered by a variety of agricultural operations and provides numerous social, economic and recreational benefits to local communities residing in the larger Sacramento and San Joaquin areas. The habitat supports many species of native wildlife, including greater and lesser Sandhill cranes, Swainson’s hawks and waterfowl that migrate throughout the Pacific Flyway.

Saturday, September 20, 2014

Side-blotch lizard thermoregulation & climate change

Top: A side-blotch lizard. Photo Credit M. Goller. Below 
Thermograms of temperature microhabitats in the overall 
landscape (A–B) and analysis of lizard and environmental
 temperature (C–D). Measurement of lizard average temperature
 (line) and perch temperature (outline) is seen in (C). (D) 
Determination of maximum lizard temperature (box) and 
environmental maximum and minimum from the entire visible 
substrate available to the lizard. Only the rock surface (arrows 
indicate rock outline) was included in environmental analyses.
Ectotherms are well known for using behavioral  thermoregulation  to optimize physiological processes. Thermoregulation is a complex problem because different physiological processes and behaviors achieve performance optima at different temperatures. Lizards usually  thermoregulate by choosing when to be active throughout the day and by shuttling between microhabitats of differing temperatures. Ectotherms usually follow a daily cycle of thermal microhabitat preference. Thus the potential for behavioral thermoregulation is limited by the available thermal niches, and the number of microhabitats available for regulating body temperatures.

In a recently published paper Goller et al. (2014) examined the impact of  habitat structural complexity on thermal microhabitats for thermoregulation using the side-blotch lizard, Uta stansburiana. Thermal microhabitat structure, lizard temperature, and substrate preference were simultaneously evaluated using thermal imaging.  Lizard thermal preference data were collected by measuring environmental and lizard temperatures simultaneously with an infrared camera.  The authors approached a lizard and either filmed at 10 frames/sec or photographed at 0.1 frames/sec for varying lengths of time (minimum of 10–25 min, up to several hours). The environment around the lizard was included in each frame, so that available thermal niches could be assessed.

They found a broad range of microhabitat temperatures was available (mean range of 11°C within 1–2 square meters) while mean lizard temperature was between 36°C and 38°C. Lizards selected sites that differed significantly from the mean environmental temperature, indicating behavioral thermoregulation, and they maintained a temperature significantly above that of their perch (mean difference of 2.6°C). Uta's thermoregulatory potential within a complex thermal microhabitat structure suggests that a warming trend may prove advantageous, rather than detrimental for this population.

A result of climate change will be greater variation and an increase in temperature across the range of Uta stansburiana. Although an increase in several degrees will probably provide a more optimal thermal environment for temperate species, it will also increase the chance of overheating, and rising temperatures may render habitats with less thermal heterogeneity unsuitable for Uta. An increase in temperature may not be detrimental to the study population. Higher thermal microhabitat diversity is important as it may allow behavioral thermoregulation to a preferred temperature in varying temperature conditions. Ability to thermoregulate by moving into shaded microhabitats can be an important buffer of climate change and complex habitats provide shade more reliably.

Citation
Goller M, Goller F,  French SS. 2014. A heterogeneous thermal environment enables remarkable behavioral thermoregulation in Uta stansburiana.  Ecology and Evolution 2014; 4(17): 3319–3329.

Wednesday, September 10, 2014

Varanus olivaceus picks fruit from trees

Varanus olivaceus feeding in a Microcos tree – Polillo,
 May 2005. From video by Simon Normanton/ Steel Spyda.
Daniel Bennett (2014) used camera traps and direct observation to investigate the foraging behavior of the butaan, . This lizard is an obligatory frugivorous monitor lizard restricted to Luzon, Polillo and Catenduanes islands in the northern Philippines. Its diet consists almost entirely of fruit and snails. Auffenberg studied this species and stated it feeds exclusively on fallen fruit from the forest floor and rarely, if ever, took fruit from trees. However, a ten year study of the species on Polillo Island in Quezon Province found no evidence to support this assertion that the lizards typically forage on fallen fruit. Bennett gather evidence indicating that the butaan normally climbs fruiting trees of all species and picked the fruit directly from branches or syncarps. The study was carried in and around the Sibulan Watershed Reserve, Polillo Island Quezon Province in primary and secondary lowland dipterocarp forest.
Bennett found the lizards spend as little time on the ground as possible. However they never overnight in fruiting trees and suggests this is probably because the trees provide neither suitable hollows nor dense thickets in which to shelter. The lizards spent as little time as possible in fruiting trees before returning to larger trees that provide greater protection from predators, and that they appear to approach fruiting trees directly without searching for fallen fruit below the canopy makes it unlikely that they would preferentially take fruit from the ground. However, snails are probably found and consumed on the forest floor rather than in trees.

Citation

Bennett, D. (2014) The Arboreal Foraging Behavior of the Frugivorous Monitor Lizard Varanus olivaceus on Polillo Island. Biwak, 8(1), 15-18.

Nidovirus in Ball Pythons

Researchers have identified a novel virus that could be the source of a severe, sometimes fatal respiratory disease that has been observed in captive ball pythons since the 1990s. The work is published this week in mBio®, the online open-access journal of the American Society for Microbiology.

Investigators observed the virus, which they named ball python nidovirus, in eight snakes with pneumonia; virus levels were highest in the animals' lungs and other respiratory tract tissues. The team also sequenced the genome of the virus, finding it to be the largest of any RNA virus yet described.

Ball pythons have become one of the most popular types of reptiles sold and kept as pets, the authors said, because of their relatively modest size, docile behavior and ease of care. Respiratory disease has been noted in these animals since the 1990s but until now a potential cause has not been identified, said senior study author Joseph L. DeRisi, PhD, chair of the Department of Biochemistry and Biophysics at the University of California, San Francisco, in part because of the limitations of available technology.

"This is really exciting because up to this point there have been no known viruses of this type in reptiles," DeRisi said. "Some of the most feared diseases we know of, like Ebola virus, HIV, Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS), did not arise from people but have been transferred originally from animals. Our work suggests there may be very large reservoirs of genetic diversity of viral families that can cause human disease in under studied organisms, like reptiles. We would do well to look broadly across all species."

DeRisi and colleagues at seven other institutions across the country studied tissue samples from ball pythons with symptoms of respiratory disease from seven collections in Florida, Oklahoma, Pennsylvania, Texas and Wisconsin. Autopsies on the animals found lesions in the animals' upper and lower respiratory tracts, and additional lesions in other areas of the body. Using an electron microscope, investigators observed virus-like particles in the cells lining the lungs of two snakes.

To identify a cause of disease, the scientists used a technique called shotgun metagenomics to sequence RNA of eight of the snakes, finding a novel nidovirus in all of them, but not in a search of tissues from 57 other snakes not affected by pneumonia, collected for other studies. Additional work found that the virus was most prevalent in the sick animals' respiratory tract tissue, and that the nidovirus is most similar to a subset of the nidoviruses called toroviruses, which infect mammals and ray-finned fish.

"The identification of a novel nidovirus in reptiles contributes to our understanding of the biology and evolution of related viruses, and its association with lung disease in pythons is a promising step toward elucidating an etiology for this long-standing veterinary disease," DeRisi said. "Our report will enable diagnostics that will assist in determining the role of this virus in the causation of disease, which would allow control of the disease in zoos and private collections."

Yet to be determined, said study coauthor Mark Stenglein, PhD, is how the virus is spread, whether ball pythons are the primary natural host for the virus, and how widespread the virus is in the wild. In a previous study published in mBio in August 2012, DeRisi, Stenglein and colleagues discovered the first reptile arenavirus. The team is continuing work identifying reptilian viruses. "I think it's the tip of the iceberg," DeRisi said. Indeed, within the same month, two additional groups reported identification of a nearly identical virus, in a total of five additional pythons, all with lung disease.

Citation


Mark D. Stenglein et al. Ball Python Nidovirus: a Candidate Etiologic Agent for Severe Respiratory Disease in Python regius. mBio, September 2014 DOI: 10.1128/mBio.01484-14

Wednesday, September 3, 2014

Could ecdysis in wild reptiles be influenced by environmental conditions?

Anecdotal reports that ecdysis in the Southeast Asian tropical viper Calloselasma rhodostoma occurs when humidity is high. Humidity may be important during ecdysis to prevent dehydration, a risk of the increased activity required for shedding and potentially increased rates of cutaneous water loss. However, little is known about the role of humidity in ecdysis cycles in natural populations of reptiles. We here report an aggregation of Eastern Ratsnakes (Pantherophis alleghaniensis, formerly Elaphe obsoleta) that exhibited synchronized ecdysis, apparently linked to humidity. The thermal ecology of P. alleghaniensis has been relatively well described, but there seems no existing information on the role of humidity in behavior, nor of synchronized ecdysis in wild populations. Bradley Carlson and colleagues made observations at Penn State University’s Russell E. Larson Agricultural Research Center at Rock Springs, Centre Co., Pennsylvania, suggesting humidity stimulates ecdysis in the Eastern Ratsnake. On May 13, the authors first noticed P. alleghaniensis in the rafters of an old barn located on the edge of the forest. Over the next 11 days, P. alleghaniensis were observed in the barn on most days, appearing to be absent only during particularly hot or cool weather. As many as six P. alleghaniensis were observed at one time. They were usually motionless, coiled up, or stretched along a beam. Many of the snakes, exhibited cloudy, bluish eyes and/or dull body coloration, indicative of the onset of ecdysis. On 29 May, shed skins (but no snakes) were found in the barn, and no recent skins had been found before this date. The authors collected the skins determined they were from at least four individuals based on the number of heads represented and the total length of the skins. No other snake species besides P. alleghaniensis occur at this location consistent with the size and scalation on the shed skins. An examination of weather records from the nearest weather station indicated that this large number of shed skins appeared after a day characterized by a high peak in humidity and a significant rain event during the observation period. This was preceded about one week earlier by elevated humidity and rainfall as well. This strengthens previous suggestions of synchronized shedding in wild snakes. Furthermore, it suggests that these ratsnakes took refuge at the same (and potentially environmentally favorable) site for ecdysis until some environmental factor may have triggered ecdysis. The most probable cause appears to be favorable levels of humidity coupled with rainfall, which may have been potentiated by an earlier period (19–23 May) of elevated humidity and rain. The authors could not rule out other environmental factors or that shedding occurred at certain period after the snakes emerged from a hibernacula or in preparation for egg laying.

Citation
Carlson, B. E., Williams, J., & Langshaw, J. 2014. Is synchronized ecdysis in wild ratsnakes (Pantherophis alleghaniensis) linked to humidity? Herpetology Notes, SEH 7: 471-473

Saturday, August 30, 2014

Minnesota prairie snakes

The following is from the Bemidji Pioneer
Elizabeth Baier, MPR.org | 91.3 FM
Jeff LeClere, a herpetologist with the Minnesota Department of 
Natural Resources, holds an American racer snake Wednesday 
morning his team trapped and tagged. Alex Kolyer | MPR news
Kellogg — In a sandy tract of grassland where the Zumbro River empties into the Mississippi, Jeff LeClere wades in waist-high grass.

The scientist’s visit to Weaver Dunes, is the latest foray to the area where researchers have long studied turtles, falcons, bald eagles and other wildlife populations.

But LeClere isn’t looking up. Instead, he has his eyes open for reptiles that slither in the grass. A herpetologist for the Minnesota Biological Survey, LeClere is leading its effort to catalog Minnesota’s snake species and estimate their population.

That mission brought LeClere to the dunes in search of Porchy, a bullsnake, which is one of a half dozen snake species he is tracking in southeastern Minnesota. The region has the most diverse snake population in the state, with 15 of the state’s 17 snake species. Minnesota is home to two venomous snakes, both rattlesnakes.

Bullsnakes are on the decline but it’s hard to know exactly how much, LeClere said, because of their stealthy nature.

With that in mind, researchers have surgically implanted transmitters into snakes to track them. So when LeClere came to the river bank earlier this week, he pulled out a three-pronged antenna, connected it to a radio receiver and pointed it different directions. As the receiver searched for a frequency emitted by a transmitter, he listened for an electronic beep.

“It will let me know exactly where the snake it, which direction I should be going,” LeClere said. “So, for instance, back where we were, over in this direction, you still get the signal, it’s pretty faint. If I move the antenna in this direction, the sound really picks up, that means she’s in this direction.”

Resarchers nicknamed the bullsnake Porchy because she likes to hang out near the porch of a nearby trailer home. Because she was on the move, LeClere followed her path through an abandoned farm field filled with invasive grass and plants over sandy and uneven soil.

If snakes are in decline, he said, Minnesota’s changing landscape may account for that.

“They are a snake that needs large tracks of open prairie, which basically doesn’t exist anymore because all that’s left of our prairie are small, fragmented areas,” said LeClere, who has been collecting data for a year. “So when you get to a place like where we’re studying these snakes and a couple of other areas of the state that still have a decent amount of prairie left, those are worthy of studying.”

The snakes are worthy of study, LeClere said, because their disappearance from the environment can have wider ecological consequences. Snakes are often considered top predators and consume large numbers of insects and small mammals like rats and mice.

But they tend to have a bad reputation and a lot of people are scared of them, often killing them.

“Another misconception is that snakes will chase you. And I’ve heard stories where people swear that snakes will chase them down,” LeClere said. “And believe me, I’ve been chasing snakes all of my life and I’ve never had one chase me, so we’ve had a few people who just vehemently do not like snakes and the probably will never change their mind. But for the most part, people have been very positive.”

After following the sound of Porchy’s transmitter for nearly 20 minutes, the beep grew stronger.

LeClere spotted her near a gopher mound on the ground. She was clearly agitated by the presence of human invaders.

Yellow with black and brown blotches, about 5 feet long and as thick as a tube of toilet paper, Porchy weighs about two pounds.

As LeClere bent to grab her, he noticed the snake’s glistening skin.

“She shed recently,” he said. “She’s got good weight. She’s nice and thick, means she’s been eating well. This is good news because it means she’s behaving normally.”

After a few minutes, LeClere put Porchy back on the ground and the snake disappeared into the prairie.

His job done, he pulled a clipboard from his backpack and began noting his observations on the snake, its behavior and environment.


When the project ends this fall, he hopes to provide reliable information to wildlife manager and landowners about where snakes like Porchy feed, where they nest, and how they move to help preserve an important part of the state’s ecosystem.

Monday, August 25, 2014

Marine crocodilians and sea surface temperatures

A dyrosaurid, a marine crocodilian, swimming in the warm 
surface waters during the end of the Cretaceous period. Illustration 
credit: Guillaume Suan.

The ancestors of today's crocodiles colonized the seas during warm phases and became extinct during cold phases, according to a new Anglo-French study which establishes a link between marine crocodilian diversity and the evolution of sea temperature over a period of more than 140 million years.

The research, led by Dr Jeremy Martin from the Université de Lyon, France and formerly from the University of Bristol, UK is published this week in Nature Communications.

Today, crocodiles are 'cold-blooded' animals that mainly live in fresh waters but two notable exceptions, Crocodylus porosus and Crocodylus acutus venture occasionally into the sea. Crocodiles occur in tropical climates, and they are frequently used as markers of warm conditions when they are found as fossils.

While only 23 species of crocodiles exist today, there were hundreds of species in the past. On four occasions in the past 200 million years, major crocodile groups entered the seas, and then became extinct. It is a mystery why they made these moves, and equally why they all eventually went extinct. This new study suggests that crocodiles repeatedly colonized the oceans at times of global warming.

Lead author of the report, Dr Jeremy Martin said: "We thought each of these evolutionary events might have had a different cause. However, there seems to be a common pattern."

Dr Martin, with a team of paleontologists and geochemists from the Université de Lyon and the University of Bristol, compared the evolution of the number of marine crocodilian fossil species to the sea temperature curve during the past 200 million years. This temperature curve, established using an isotopic thermometer, is widely applied for reconstruction of past environmental conditions and in this case, is based on the isotopic composition of the oxygen contained in the fossilized remains of fossil marine fish (bone, teeth, scales).

Co-author, Christophe Lécuyer explained: "According to this method, it is possible to calculate the temperature of the water in which these fish lived by applying an equation linking the isotopic composition of the fossilized remains to the temperature of mineralization of their skeleton. The seawater temperatures derived from the composition of fish skeleton thus corresponds to the temperature of water in which the marine crocodiles also lived."

The results show that colonization of the marine environment about 180 million years ago was accompanied by a period of global warming of the oceans. These first marine crocodilians became extinct about 25 million years later, during a period of global freezing. Then, another crocodilian lineage appeared and colonised the marine environment during another period of global warming.

The evolution of marine crocodilians is therefore closely tied to the temperature of their medium, and shows that their evolution and their lifestyle, as in modern crocodilians, are constrained by environmental temperatures.

Nevertheless, one fossil lineage does not appear to follow this trend. Jurassic metriorhynchoids did not go extinct during the cold spells of the early Cretaceous, unlike the teleosaurids, another group of marine crocodilians. Quite surprisingly, metriorhynchoids only disappeared a few million years later. This exception will certainly provide grounds for new research, particularly into how the biology of this group adapted to life in the pelagic environment.

Professor Michael Benton from the University of Bristol, another co-author of the study, said: "This work illustrates a case of the impact of climate change on the evolution of animal biodiversity, and shows that for crocodilians, warming phases of our earth's history constitute ideal opportunities to colonise new environments.

Citation

Jeremy E. Martin, Romain Amiot, Christophe Lécuyer, Michael J. Benton. 2014. Sea surface temperature contributes to marine crocodylomorph evolution. Nature Communications, 5 DOI: 10.1038/ncomms5658.

Saturday, August 23, 2014

The identity of the long confused snake Elapotinus picteti



Top left: The snake Elapotinus pictei, Bottom left: a scan of its skull showing
 the rear fangs. Right a map of its distribution showing is association with 
rainforest. Adapted from Kucharzewski et al.
The snake Elapotinus picteti Jan, 1862 has been an enigma, it was described without locality data. The genus and species were both based on the holotype and the species was considered to belong to the venomous African Aparallactinae (family Lamprophiidae) for more than a century. However, the snake was never re-discovered but it was accepted as a valid species until present.

Christoph Kucharzewski of the Museum für Naturkunde’s Leibniz-Institut für Evolutions- und Biodiversitätsforschung in Berlin, Germany and colleagues (2014) have now clarified the taxonomic
status of E. picteti.

The authors compared its characters the literature and identification keys for the snakes across the globe. A literature survey and subsequent study of type specimens revealed that the monotypic Elapotinus is a subjective senior synonym of the monotypic Malagasy pseudoxyrhophiine snake genus Exallodontophis Cadle, 1999, a snake characterized by its unique aglyphous dentition.

Elapotinus picteti is an amazing example how missing locality data, erroneous assumptions and character descriptions can combine and lead to misleading conclusions. Elapotinus was a problematic from the beginning and this in part explains why it took more than 150 years to unravel this taxonomic mystery.

First, there was no type locality given in the original description and the species resembles snakes that evolved convergently in Africa, Madagascar, and South America. Boulenger suggested tropical Africa as possible locality, eighty years later Mahnert suggested a Neotropical origin.
Second, there was uncertainty and confusion concerning the dentition of the species. Jan (1862a, b) described the maxillary teeth of his Elapotinus picteti as ungrooved and the teeth position similarly to Amblyodipsas. Without examination of the type material Boulenger (1896) decided to list the species within the opisthoglyphous Dipsadomorphinae and related to the African Aparallactinae and the Neotropical Elapomorphini. The error regarding dentition introduced by Boulenger led subsequent authors to list the species in the Aparallactinae as part of the family Lamprophiidae from continental Africa.

The authors transfer Elapotinus from the lamprophiid subfamily Aparallactinae to the subfamily Pseudoxyrhophiinae. Furthermore, Elapotinus picteti strongly resembles the Malagasy species Exallodontophis albignaci (Domergue, 1984) in external morphology, coloration and dentition. As a consequence we consider Elapotinus picteti a subjective senior synonym of Exallodontophis albignaci.

Citation

Kucharzewski, C, et al. 2014. A taxonomic mystery for more than 150 years: Identity, systematic position and Malagasy origin of the snake Elapotinus picteti Jan, 1862, and synonymy of Exallodontophis Cadle, 1999 (Serpentes: Lamprophiidae). Zootaxa 3852.2 (2014): 179-202.

Tuesday, August 19, 2014

A new snake from Trinidad, and its significance to the big picture


There is no doubt that there are many, many more species of amphibians and reptiles than previously thought. Peter Uetz, maintains the Reptile Database website, and he recently announced that in 2014, the number of known reptile species passed the 10,000 mark – and the year has not yet ended. In an email Uetz wrote the number of reptile species is, “10,038 species (including 79 described this year), up from 9,952 in April”While some of these species are obviously different, many of them are cryptic, and it takes some detailed study of morphology or DNA to sort them out.

Trinidad is a relatively small island – 4800 square kilometers that has had its herpetofauna relatively well studied. The first list of herps was published in 1858, and the work by Mole and Urich at the turn of the 20th century examined the fauna extensively. William Beebe spent the last years of his life at Simla in the Arima Valley and published a fauna list as well as a paper on the ecology of the valley. Garth Underwood and Michael Emsley also studied and wrote about the island’s herpetofauna. Julian Kenny and Hans Boos were also actively working on the Trinidad herpetofauna for decades. And I made five- or six trips to the islands and examined museum specimens in the 1980-90’s for the 1997 book. During those trips, I frequently stayed at Simla and worked extensively in the Arima Valley. In 2010, I decided to take a second look at the fauna and since that date have made eight trips to investigate the herpetofauna of both Trinidad and Tobago. Additionally, I have been working with colleagues to compare museum material from the islands to those from the mainland – the results are startling.

It has become quite obvious to me that the diversity of reptiles on that 4800 sq km, well studied island (as well as the island of Tobago) is much greater than what I (or anybody else) thought it was in 1990.

Within the last few years, we have described Plica caribeana and Leptophis haileyi. The Plica is a Caribbean Coastal Range species, and the Leptophis appears to be a Tobago endemic. There are more species forthcoming – for the most part it is a matter of time and money to get the work done. But, preliminarily we have identified at least ten more species of squamate reptiles currently unrecognized from the islands or masquerading under the name of a widespread species.

In a forthcoming paper in the Journal of South American Herpetology, Teddy Angarita-Sierra describes a new, cryptic species of coffee snake, in the genus Ninia – from Trinidad. It would normally not surprise me, that a small, leaf litter dwelling snake would go un-noticed in the tropics. But, this snake is surprising because the of the type locality – Simla. A location that has to be the most closely examined piece of real estate on the island – in terms of its fauna.

Ninia atrata left, Nina franciscoi sp. n. right. T. Angarita-Sierra
Angarita-Sierra describes Ninia franciscoi, from a single specimen collected at Simla 6 March 1988 by William B. Montgomery and David Resnick. This specimen looks very much like the widespread Ninia atrata (also found at Simla) except for the number of upper labials contacting the primary temporal and most importantly, an unusually shaped hemipensis (see right).

Nina franciscoi sp n.,top, Nina atrata bottom.
After reviewing this paper – I went back and looked at about forty specimens of Ninia atrata from Trinidad and Tobago as well as all of my photographs, looking to see if any of the others had the primary temporal in contact with three upper labials. Some of these specimens were collected at Simla – none showed this trait.

So, what is the significance of this? Below is a power point slide I used in a recent presentation comparing the number of reptile species per 1000 km2 in Trinidad & Tobago to Venezuela. The islands are much better studied than the mainland. Trinidad & Tobago have 4.2x more known species of reptiles per 1000 km2 than does Venezuela (this is using the numbers from the 1997 book). In other words mainland South America (specifically Venezuela) most likely has a vast number of undescribed reptiles.


As for those undescribed Trinidad and Tobago squamates - one of them is a third species of Ninia. Below is typical Ninia atrata







Vocal communication in Amazon River Turtles

An adult Giant South American river turtle. The turtle 
is the largest member of the side-necked turtle family and 
grows up to nearly three feet in length. Photo credit: C. 
Ferrara/Wildlife Conservation Society
Turtles are well known for their longevity and protective shells, but it turns out these reptiles use sound to stick together and care for young, according to the Wildlife Conservation Society and other organizations.

Scientists working in the Brazilian Amazon have found that Giant South American river turtles actually use several different kinds of vocal communication to coordinate their social behaviors, including one used by female turtles to call to their newly hatched offspring in what is the first instance of recorded parental care in turtles.

"These distinctive sounds made by turtles give us unique insights into their behavior, although we don't know what the sounds mean," said Dr. Camila Ferrara, Aquatic Turtle Specialist for the WCS Brazil Program. "The social behaviors of these reptiles are much more complex than previously thought."

Some behaviors of the Giant South American river turtle have been well known for some time, including the tendency to aggregate in huge numbers during the nesting season. However, the mechanisms used by turtles to coordinate their activities have yet to be explained. This study focused on the sounds made by the turtles as a possible means of facilitating social behavior.

Working on the Rio Trombetas between 2009 and 2011, the research team captured 270 individual sounds made during 220 hours of recording made with both microphones and hydrophones when the turtles were swimming through the river. The scientists then conducted spectrographic analyses on the repertoire, which they subdivided into six different types of vocalization made by turtles during the nesting season, which begins as the reptiles leave the seasonally flooded forest for nesting beaches along river banks. The scientists also sought to correlate vocalizations with specific behaviors.

Sounds made by the turtles while migrating through the river or basking tended to be low frequency sounds, possibly to facilitate contact between turtles over longer distances. Vocalizations made during nesting tended to be higher frequency sounds, possibly because higher frequency sounds travel better in shallow water and in the air.

The highest diversity of sounds are used by females about to nest; the researchers theorize that the animals use these sounds to decide on a specific nesting site and to synchronize their movements (the turtles leave the water in a single-file procession).

The hatchling turtles themselves make sounds before they hatch and continue to do so as they clamber out of the nest chamber on the river beach. The sounds, the authors speculate, may stimulate group hatching. The females, in turn, vocalize in response to the nestling calls, perhaps guiding the nestlings into the water. These interactions -- the first recorded instance of parental care in turtles -- were featured in a 2012 study appearing in the Journal of Comparative Psychology.
Using sonic transmitters, the team also discovered that the hatchlings remain together and migrate with adult females for more than two months.

The Giant South American river turtle is the largest of the side-necked turtle family and grows up to 80 centimeters (nearly three feet) in length. The species is only found in the Amazon River basin and is now threatened by unregulated consumption of the turtles' meat and eggs.

"Groundbreaking studies such as this one can help us better understand the complex relationships between both individual animals and their environment," said Dr. Julie Kunen, Executive Director of WCS's Latin America and the Caribbean Program. "Protecting the still sizable populations of Giant South American river turtles will also enable us to conserve the behavioral richness of these reptiles for future study."

Research on the Giant South American river turtles is part of a new long-term WCS conservation program called Amazon Waters, an initiative focusing on the conservation of aquatic ecosystems and species.

Citation
Ferrara CR, Vogt RC, Sousa-Lima RS, Tardio BMR, Bernardes VCD.  2014. Sound Communication and Social Behavior in an Amazonian River Turtle (Podocnemis expansa). Herpetologica, 70:149 DOI: 10.1655/HERPETOLOGICA-D-13-00050R2