Wednesday, February 22, 2017

Tiny frogs from the Western Ghats

Seven new species discovered from the Western Ghats. A. Radcliffe's Night Frog (Nyctibatrachus radcliffei), B. Athirappilly Night Frog
 (Nyctibatrachus athirappillyensis), C. Kadalar Night Frog (Nyctibatrachus webilla), D. Sabarimala Night Frog (Nyctibatrachus sabarimalai),
 E. Vijayan's Night Frog (Nyctibatrachus pulivijayani), F. Manalar Night Frog (Nyctibatrachus manalari), G. Robin Moore's Night Frog.
[(D-G. Size of the miniature species in comparison to the Indian five-rupee coin (24 mm diameter)]. Photo Credit: SD Biju
Scientists from India have discovered seven new frog species belonging to the genus Nyctibatrachus, commonly known as Night Frogs. This find is a result of five years of extensive explorations in the Western Ghats global biodiversity hotspot in India. Four out of seven of the new species are miniature-sized frogs (12.2-15.4 mm), which can comfortably sit on a coin or a thumbnail. These are among the smallest known frogs in the world.

Unlike other frogs in the genus that are predominantly stream dwelling, the new miniature frogs were found under damp forest leaf litter or marsh vegetation. Scientists were surprised by the relative abundance of these previously unknown species at their collection localities. "In fact, the miniature species are locally abundant and fairly common but they have probably been overlooked because of their extremely small size, secretive habitats and insect-like calls," says Sonali Garg who undertook this study as part of her PhD research at University of Delhi.

In the lab, the newly sampled frogs were confirmed as new species by using an integrated taxonomic approach that included DNA studies, detailed morphological comparisons and bioacoustics. Evidence from these multiple sources confirmed that the diversity of Night frogs is higher than previously known and particularly remarkably for the miniaturized forms. Previously, the Night Frog genus composed of 28 recognized species of which only three were miniature-sized.

Now the total number of known Nyctibatrachus species has increased to 35, of which 20 percent are diminutive in size. This frog genus is endemic to the Western Ghats of India and represents an ancient group of frogs that diversified on the Indian landmass approximately 70-80 million years ago.

The discovery of several new species of ancient origin can provide useful insights into the evolution of endemic frog lineages in the Western Ghats, which is a leading amphibian hotspot. The past decade has witnessed an exponential increase in the number of new amphibian species described from this region. Of the total new species of amphibians (1581) described globally between the years 2006-2015, the highest number were from the Brazilian Atlantic Forest (approximately 182) followed by the Western Ghats-Sri Lanka biodiversity hotspot (approximately 159), with 103 species described alone from the Western Ghats region.

However, the future of many of the new species may be bleak. All the newly described species are currently known only from single localities in the southern Western Ghats, and some lie outside Protected areas. Researchers found the Radcliffe's Night frog and the Kadalar Night Frog inside private or state-owned plantation areas facing threats such as habitat disturbance, modification and fragmentation. The Athirappilly Night Frog was found in close vicinity to the Athirappilly waterfalls and the Sabarimala Night Frog near the Sabarimala pilgrimage centre, both of which are disturbed by anthropogenic activities. "Over 32 percent, that is one-third of the Western Ghats frogs are already threatened with extinction. Out of the seven new species, five are facing considerable anthropogenic threats and require immediate conservation prioritization," says Prof SD Biju, who led the new study and has also formally described over 80 new species of amphibians from India

Citation
Sonali Garg, Robin Suyesh, Sandeep Sukesan, SD Biju. Seven new species of Night Frogs (Anura, Nyctibatrachidae) from the Western Ghats Biodiversity Hotspot of India, with remarkably high diversity of diminutive forms. PeerJ, 2017; 5: e3007 DOI: 10.7717/peerj.3007

Tuesday, February 21, 2017

Phylogenetics of Kingsnakes in the Lampropeltis getula Complex, in Eastern North America

Distribution of kingsnakes in the Lampropeltis getula complex in North America:
 (A) Lampropeltis californiae (banded); (B) Lampropeltis holbrooki;
 (C) Lampropeltis nigra; (D) Lampropeltis getula getula; (E) Lampropeltis getula 
“sticticeps”; (F) Lampropeltis getula floridana; (G–I) Lampropeltis getula 
meansi (patternless, striped, and wide-banded, respectively); (J) Lampropeltis 
splendida; (K) Lampropeltis getula nigrita; (L) Lampropeltis californiae 
(striped). Distributions are modified after Conant and Collins (1998),
 Krysko (2001), Stebbins (2003), Krysko and Judd (2006), and 
Pyron and Burbrink (2009a, 2009b).
Kingsnakes of the Lampropeltis getula complex range throughout much of temperate and subtropical North America; along the Pacific coast from Oregon southward to the Mexican Plateau, and eastward to New Jersey and southward to Florida. Kingsnakes of this species complex are extremely variable in color pattern, and therefore, along with their mostly docile disposition, are easily recognizable and very popular in the pet trade.The distinct morphology and color patterns found in the Lampropeltis getula complex, along with its transcontinental geographic distribution and occasional disjunct populations across the North American
Distribution and locations of samples sequenced for kingsnakes 
of the Lampropeltis getula complex in eastern North America: yellow 
dots = Lampropeltis getula floridana from Florida peninsula; blue dots = 
Lampropeltis getula getula from the Atlantic coast; red dots = Lampropeltis 
getula meansi from the Eastern Apalachicola Lowlands in the Florida 
panhandle; gray dots = morphological intermediates between L. g. floridana
 and L. g. getula; and coral dots = morphological intermediates between 
L. g. getula and L. g. meansi. Green and pink polygons refer to Lampropeltis
 nigra and Lampropeltis holbrooki, respectively, on the western side of the 
Appalachian Mountains. Distributions are modified after Conant and 
Collins (1998), Krysko (2001) using multi-locus phylogeny, 
and Krysko and Judd (2006) using morphology.
landscape make a fascinating subject for phylogeography. In a new paper Krysto et al (2017) expanded the sample from the getula complex and add a nuclear DNA locus to the molecular data set  used previously to hypotheses distinct genetic lineages. They use genetic and ecological methods to test previous hypotheses of distinct evolutionary lineages by examining 66 total snakes for: analyzing phylogeographic structure using 2 mtDNA loci and 1 nuclear locus; estimating divergence dates and historical demography among lineages in a Bayesian coalescent framework, and; applied ecological niche modeling (ENM). The molecular data and ENMs illustrate that three previously recognized subspecies in the eastern United States comprise well-supported monophyletic lineages that diverged during the Pleistocene. The geographic boundaries of these three lineages correspond closely to known biogeographic barriers (Florida peninsula, Appalachian Mountains, and Apalachicola River) previously identified for other plants and animals, indicating shared geographic influences on evolutionary history. Them authors conclude that genetic, ecological, and morphological data support recognition of these 3 lineages as distinct species (Lampropeltis floridana, Lampropeltis getula, and Lampropeltis meansi).

Citation
Krysko KL, Nuñez LP, Newman CE, Bowen BW. Phylogenetics of Kingsnakes, Lampropeltis getula Complex (Serpentes: Colubridae), in Eastern North America. The Journal of heredity. 2017 Jan 24.

Saturday, February 18, 2017

Climatic and geographic predictors of life history variation in Eastern Massasauga, Sistrurus catenatus

A juvenile Eastern Massasauga. Photo credit: Eric Hileman.

A new study is bringing attention to a little known and imperiled rattlesnake that slithers among the wetlands in regions surrounding the Great Lakes.

The Eastern Massasauga rattler was once common in such states as Indiana and Illinois. Until recent years, it could still be found in Chicago's Cook County. But the reptile's range and numbers have been steadily declining. In 2016, the snake was listed as threatened under the U.S. Endangered Species Act.

In the new study, Northern Illinois University biological sciences professor Richard King and his former student Eric Hileman examine the life history of the Eastern Massasauga, revealing important local climate impacts on the snake that should be carefully weighed when developing conservation strategies.

"Our results provide evidence that climatic variation in the Great Lakes region strongly influences body size, individual growth rates and key aspects of reproduction," says Hileman, first author of the study published in PLOS ONE, a journal of the Public Library of Science. Hileman earned his Ph.D. in biological sciences from NIU in December and is now a postdoctoral fellow in biology at Trent University in Ontario, Canada.

Hileman, King and more than 40 co-authors gathered and synthesized more than a century of data on the snakes from study sites across the range of the Eastern Massasauga. Most of the data was culled from studies conducted from the mid-1990s forward at sites in Illinois, Indiana, Wisconsin, Michigan, Iowa, Ohio, Pennsylvania and New York, as well as Ontario, Canada.

The scientists found strong evidence for geographic variation in six of nine life-history variables. Among the findings:

The average body size of the snake and the size of its offspring increased with increasing mean annual precipitation, possibly because wetter climates yield greater prey abundance.

Litter sizes decreased with increasing mean temperature, and increased by one offspring for each 1.89-degree increase in latitude, even when maternal size was held constant.

"It's been rare to look within a species and show that these patterns exist," King says. "The study results demonstrate that a one-size-fits all conservation strategy is not appropriate. Rather, assessments of extinction risk and the design of management strategies need to account for geography."

The Eastern Massasauga snakes are generally found in wet prairies or sedge meadows, where the reptiles employ a sit-and-wait strategy to catch and feed on small mammals. Adult size ranges from about 2 feet to 2 ½ feet in length. While venomous, the snakes are not particularly aggressive or dangerous to work with.

"You're not likely to encounter them unless you're looking for them," King says. "It's easy to walk right by one. They're very cryptically colored to look like dead leaves and cattails, so they blend in exceedingly well."

The reptiles suffered habitat loss from extensive drainage of land for agriculture and development. As recently as the 1970s, some states had bounties on the snake.

With concerns over whether they would persist in the wild, the remaining snakes in Chicago's Cook County were taken into a captive breeding program in 2010, King says.

"In Illinois, they've nearly blinked out entirely," he adds. "We're probably down to one location in the southern part of the state that has a stable population. They seem to have stronger holds in Michigan and southern Ontario."

The study authors believe findings will aid Eastern Massasauga recovery efforts.

"The life-history parameter estimates will be essential for improving models related to extinction risk and climate change," Hileman says. "The results from these predictive models can subsequently be used to develop site-specific management strategies."


Citation

Eric T. Hileman, Richard B. King, John M. Adamski, Thomas G. Anton, Robyn L. Bailey, Sarah J. Baker, Nickolas D. Bieser, Thomas A. Bell, Kristin M. Bissell, Danielle R. Bradke, Henry Campa, Gary S. Casper, Karen Cedar, Matthew D. Cross, Brett A. DeGregorio, Michael J. Dreslik, Lisa J. Faust, Daniel S. Harvey, Robert W. Hay, Benjamin C. Jellen, Brent D. Johnson, Glenn Johnson, Brooke D. Kiel, Bruce A. Kingsbury, Matthew J. Kowalski, Yu Man Lee, Andrew M. Lentini, John C. Marshall, David Mauger, Jennifer A. Moore, Rori A. Paloski, Christopher A. Phillips, Paul D. Pratt, Thomas Preney, Kent A. Prior, Andrew Promaine, Michael Redmer, Howard K. Reinert, Jeremy D. Rouse, Kevin T. Shoemaker, Scott Sutton, Terry J. VanDeWalle, Patrick J. Weatherhead, Doug Wynn, Anne Yagi. Climatic and geographic predictors of life history variation in Eastern Massasauga (Sistrurus catenatus): A range-wide synthesis. PLOS ONE, 2017; 12 (2): e0172011 DOI: 10.1371/journal.pone.0172011

Sunday, February 12, 2017

Gliding lizards use the position of the sun to enhance social display

Sulawesi Lined Gliding Lizard (Draco spilonotus
showing the sun on the dewlap
Photo A. S. Kono/Wikamedia
In a recent paper, Klomp et al. describe how a gliding lizard in the genus Draco orient their body to the sun so that the light emphasizes their display. The following is the abstract from the paper.

Effective communication requires animal signals to be readily detected by receivers in the environments in which they are typically given. Certain light conditions enhance the visibility of colour signals and these conditions can vary depending on the orientation of the sun and the position of the signaller. We tested whether Draco sumatranus gliding lizards modified their position relative to the sun to enhance the conspicuousness of their throat-fan (dewlap) during social display to conspecifics. The dewlap was translucent, and we found that lizards were significantly more likely to orient themselves perpendicular to the sun when displaying. This increases the dewlap's radiance, and likely, its conspicuousness, by increasing the amount of light transmitted through the ornament. This is a rare example of a behavioural adaptation for enhancing the visibility of an ornament to distant receivers.

Citation
Klomp DA, Stuart-Fox D, Das I, Ord TJ. 2017. Gliding lizards use the position of the sun to enhance social display. Biology Letters. 2017 Feb 1;13(2):20160979.

Successful reintroduction of the critically endangered Antiguan racer Alsophis antiguae to offshore islands in Antigua, West Indies.

The following is an abstract recently published in the International Zoo Yearbook.

The Critically Endangered Antiguan racer Alsophis antiguae is endemic to Antigua and Barbuda (441 km2 area) but declined following the arrival of invasive mammals. By 1995, only an estimated 51 Antiguan racers survived on an offshore islet (Great Bird Island: 8·4 ha), many of which had injuries consistent with rat bites. To prevent extinction, a consortium of national and international organizations eradicated the Black rats Rattus rattus from Great Bird Island in 1995 and the snake population promptly doubled in size. The agencies then embarked on a program to eradicate invasive rats and, where present, Small Asian mongooses Herpestes javanicus from a further 14 islands around Antigua. The first reintroduction was carried out in November 1999, with ten wild racers translocated from Great Bird Island to Rabbi Island. Further reintroductions followed to Green Island (from October 2002) and York Island (from January 2008), bringing the total area of occupancy for racers to 63 ha. The translocated racers appeared to thrive in their new habitats and reproduced almost immediately. The reintroduction program was underpinned by field research, fundraising and an innovative education campaign to address prevailing negative attitudes towards snakes. While the Antiguan racer metapopulation has increased to > 1100 individuals in the wild, lasting success depends on Great Bird, Rabbit, Green and York Islands being fully protected from invasive mammals and harmful developments. To spread the risk, additional reintroduction sites must be identified.

Daltry JC, Lindsay K, Lawrence SN, Morton MN, Otto A, Thibou A. 2017. Successful reintroduction of the Critically Endangered Antiguan racer Alsophis antiguae to offshore islands in Antigua, West Indies. International Zoo Yearbook. 2017 

Wednesday, February 8, 2017

A new Fish-scale gecko in the genus Geckolepis

The new fish-scale gecko, Geckolepis megalepis, has the largest body scales of 
all geckos. This nocturnal lizard was discovered in the 'tsingy' karst formations 
in northern Madagascar. Photo Credit: F. Glaw
Many lizards can drop their tails when grabbed, but one group of geckos has gone to particularly extreme lengths to escape predation. Fish-scale geckos in the genus Geckolepis have large scales that tear away with ease, leaving them free to escape whilst the predator is left with a mouth full of scales. Scientists have now described a new species (Geckolepis megalepis) that is the master of this art, possessing the largest scales of any gecko.

The skin of fish-scale geckos is specially adapted to tearing. The large scales are attached only by a relatively narrow region that tears with ease, and beneath them they have a pre-formed splitting zone within the skin itself. Together, these features make them especially good at escaping from predators. Although several other geckos are able to lose their skin like this if they are grasped really firmly, Geckolepis are apparently able to do it actively, and at the slightest touch. And while others might take a long time to regenerate their scales, fish-scale geckos can grow them back, scar-free, in a matter of weeks.

This remarkable (if somewhat gruesome) ability has made these geckos a serious challenge to the scientists who want to study them. Early researchers described how it was necessary to catch them with bundles of cotton wool, to avoid them losing almost all of their skin. Today, little has changed, and researchers try to catch them without touching them if possible, by luring them into plastic bags. But once they are caught, the challenges are not over; identifying and describing them is even harder.

"A study a few years ago showed that our understanding of the diversity of fish-scale geckos was totally inadequate," says Mark D. Scherz, lead author of the new study and PhD student at the Ludwig Maximilian University of Munich and Zoologische Staatssammlung München, "it showed us that there were actually about thirteen highly distinct genetic lineages in this genus, and not just the three or four species we thought existed. One of the divergent lineages they identified was immediately obvious as a new species, because it had such massive scales. But to name it, we had to find additional reliable characteristics that distinguish it from the other species." A challenging task indeed: one of the main ways reptile species can be told apart is by their scale patterns, but these geckos lose their scales with such ease that the patterns are often lost by the time they reach adulthood. "You have to think a bit outside the box with Geckolepis. They're a nightmare to identify. So we turned to micro-CT to get at their skeletons and search there for identifying features." Micro-CT (micro-computed tomography) is essentially a 3D x-ray of an object. This method is allowing morphologists like Scherz to examine the skeletons of animals without having to dissect them, opening up new approaches to quickly study the internal morphology of animals.

By looking at the skeletons of the geckos, the team was able to identify some features of the skull that distinguish their new species from all others. But they also found some surprises; a species named 150 years ago, Geckolepis maculata, was confirmed to be different from the genetic lineage that it had been thought to be. "This is just typical of Geckolepis. You think you have them sorted out, but then you get a result that turns your hypothesis on its head. We still have no idea what Geckolepis maculata really is -- we are just getting more and more certain what it's not."

The new species, Geckolepis megalepis, which was described by researchers from the US, Germany, and Columbia in a paper published today in the open access journal PeerJ, is most remarkable because of its huge scales, which are by far the largest of any gecko. The researchers hypothesize that the larger scales tear more easily than smaller scales, because of their greater surface area relative to the attachment area, and larger friction surface. "What's really remarkable though is that these scales -- which are really dense and may even be bony, and must be quite energetically costly to produce -- and the skin beneath them tear away with such ease, and can be regenerated quickly and without a scar," says Scherz. The mechanism for regeneration, which is not well understood, could potentially have applications in human medicine, where regeneration research is already being informed by studies on salamander limbs and lizard tails.

Citation
Mark D. Scherz, Juan D. Daza, Jörn Köhler, Miguel Vences, Frank Glaw. 2017.  Off the scale: a new species of fish-scale gecko (Squamata: Gekkonidae: Geckolepis) with exceptionally large scales. PeerJ, 2017; 5: e2955 DOI: 10.7717/peerj.2955

Monday, February 6, 2017

Arthroleptis troglodytes rediscovered in Zimbabwe

In this Dec. 3, 2016 photo, a man holds a rare frog that 
hasn't been seen in decades, in Bulawayo, Zimbabwe. 
 Arthroleptis troglodytes, also known as the “cave 
squeaker” because of its preferred habitat, was 
discovered in 1962 but there were no reported sightings 
of the elusive amphibian after that. An international 
“red list” of threatened species tagged them as 
critically endangered and possibly extinct. 
(AP Photo/ Francois Becker)
The Arthroleptis troglodytes, below, also known as the cave squeaker because of its preferred habitat, was discovered in 1962, but there were no reported sightings of the elusive amphibian after that. An international “red list” of threatened species tagged them as critically endangered and possibly extinct.

Robert Hopkins, a researcher at the Natural History Museum of Zimbabwe, in Bulawayo, said his team had found four specimens of the frog in its known habitat of Chimanimani, a mountainous area in eastern Zimbabwe.

The research team found the first male specimen on Dec. 3 after they followed an animal call they had not heard before, Mr. Hopkins said. They then discovered two other males and a female. Mr. Hopkins said he been looking for the cave squeaker for eight years.

“I was not with my team when they were found,” he said. “I was at the base. I can no longer climb the mountains as I am 75.”

Researchers plan to breed more frogs with the ones taken from their habitat and then reintroduce them to the mountain summit. The frog is tiny and light brown with dark spots.

Now the authorities fear for the frogs’ security, especially because scientists’ and researchers’ huge interest could result in the frog being captured and illegally exported. Mr. Hopkins said 16 specimens were on display at various museums, including the British Museum.

Caroline Washaya-Moyo, a spokeswoman for the Zimbabwe National Parks and Wildlife Management Authority, said: “We are expecting an influx of scientists looking for it. We will do everything in our power to protect and conserve the frog.”

Arthroleptis troglodytes is listed as Critically Endangered by the IUCN because its extent of occurrence (EOO) is 20 km², it occurs in one threat-defined location and there is ongoing decline in the extent and quality of habitat. It was been tagged as Possibly Extinct as it was last seen in 1962 and recent surveys in 2010 failed to detect this species, although it is acknowledged that it may not have been an optimum time in which to detect the species (e.g. not during rains). Most of the specimens were collected in sinkholes or caves and a few were found in open montane grassland. It presumably breeds by direct development. There is very little direct information available for this poorly known species and threats to the species are not well understood. During a survey in 2010, the vicinity of the type locality was found to be intact. However, there are both diamond and gold mining activities locally. The diamond mine at Chimanimani is currently outside the national park, but artisanal mining is known to have caused significant riparian damage on the Zimbabwe side (supposedly worse in the southern part of the park) and is also known to take place in fluvial areas on the Mozambique side. Furthermore, rumours were circulating during a visit in 2010 that the government was considering deproclaiming part of the national park for a commercial gold mine . Thus, considering the available data, it is not implausible that mining activities pose a threat to the species. Finally, as with other species occurring in isolated montane habitats, it could be at risk from the effects of climate change.


Sunday, January 29, 2017

Oldest, most complete iguanian in the Americas

The lizard Magnuviator ovimonsensis is a newly discovered species at Egg
 Mountain in Montana,  US, at a site rich in fossils from the Cretaceous Period. 
The lizard is thought to have lived 75 million years ago. Artist credit: 
Misaki Ouchida
Paleontologists picking through a bounty of fossils from Montana have discovered something unexpected -- a new species of lizard from the late dinosaur era, whose closest relatives roamed in faraway Asia.

This ancient lizard, which lived 75 million years ago in a dinosaur nesting site, is described from stem to stern in a paper published Jan. 25 in the Proceedings of the Royal Society B. Christened Magnuviator ovimonsensis, the new species fills in significant gaps in our understanding of how lizards evolved and spread during the dinosaur era, according to paleontologists at the University of Washington and the Burke Museum of Natural History & Culture who led the study.

"It is incredibly rare to find one complete fossil skeleton from a relatively small creature like this lizard," said David DeMar, lead author and postdoctoral research associate in the UW biology department and the Burke Museum. "But, in fact, we had two specimens, both from the same site at Egg Mountain in Montana."

Right out of the gate, Magnuviator is reshaping how scientists view lizards, their biodiversity and their role in complex ecosystems during this reptile's carefree days in the Cretaceous Period 75 million years ago.

Based on analyses of the nearly complete fossil skeletons, Magnuviator was an ancient offshoot of iguanian lizards -- and they're actually the oldest, most complete iguanian fossils from the Americas. Today, iguanians include chameleons of the Old World, iguanas and anoles in the American tropics and even the infamous water-walking basilisk -- or "Jesus Christ" -- lizards. But based on its anatomy, Magnuviator was at best a distant relative of these modern lizard families, most of which did not arise until after the non-avian dinosaurs -- and quite a few lizards and other creatures -- went extinct 66 million years ago.

The team came to these conclusions after meticulous study of both Egg Mountain specimens over four years. This included a round of CT scans at Seattle Children's Hospital to narrow down the fossil's location within a larger section of rock and a second round at the American Museum of Natural History to digitally reconstruct the skull anatomy. The fact that both skeletons were nearly complete allowed them to determine not only that Magnuviator represented an entirely new species, but also that its closest kin weren't other fossil lizards from the Americas. Instead, it showed striking similarities to other Cretaceous Period iguanians from Mongolia.

"These ancient lineages are not the iguanian lizards which dominate parts of the Americas today, such as anoles and horned lizards," said DeMar. "So discoveries like Magnuviator give us a rare glimpse into the types of 'stem' lizards that were present before the extinction of the dinosaurs."

But Magnuviator's surprises don't end with the Mongolian connection. The site of its discovery is also eye-popping.

Egg Mountain is already famous among fossil hunters. Over 30 years ago, paleontologists discovered the first fossil remains of dinosaur babies there, and it is also one of the first sites in North America where dinosaur eggs were discovered.

"We now recognize Egg Mountain as a unique site for understanding Cretaceous Period ecosystems in North America," said senior author Greg Wilson, UW associate professor of biology and curator of paleontology at the Burke Museum. "We believe both carnivorous and herbivorous dinosaurs came to this site repeatedly to nest, and in the process of excavating this site we are learning more and more about other creatures who lived and died there."

The team even named their new find as homage to its famous home and its close lizard relatives in Asia. Magnuviator ovimonsensis means "mighty traveler from Egg Mountain."

Through excavations at Egg Mountain led by co-author David Varricchio at Montana State University and meticulous analysis of fossils at partner institutions like the UW and the Burke Museum, scientists are piecing together the Egg Mountain ecosystem of 75 million years ago. In those days, Egg Mountain was a semi-arid environment, with little or no water at the surface. Dinosaurs like the duck-billed hadrosaurs and the birdlike, carnivorous Troodon nested there.

Researchers have also unearthed fossilized mammals at Egg Mountain, which are being studied by Wilson's group, as well as wasp pupae cases and pollen grains from plants adapted for dry environments. Based on the structure of Magnuviator's teeth, as well as the eating habits of some lizards today, the researchers believe that it could have feasted on wasps at the Egg Mountain site. Though based on its relatively large size for a lizard -- about 14 inches in length -- Magnuviator could have also eaten something entirely different.

"Due to the significant metabolic requirements to digest plant material, only lizards above a certain body size can eat plants, and Magnuviator definitely falls within that size range," said DeMar.

Whatever its diet, Magnuviator and its relatives in Mongolia did not make it into the modern era. DeMar and co-authors hypothesize that these stem lineages of lizards may have gone extinct along with the non-avian dinosaurs. But given the spotty record for lizards in the fossil record, it will take more Magnuviator-level discoveries to resolve this debate. And, unfortunately, part of the excitement surrounding Magnuviator is that it is a rare find.

Citation
David G. DeMar, Jack L. Conrad, Jason J. Head, David J. Varricchio, Gregory P. Wilson. A new Late Cretaceous iguanomorph from North America and the origin of New World Pleurodonta (Squamata, Iguania). Proceedings of the Royal Society B: Biological Sciences, 2017; 284 (1847): 20161902 DOI: 10.1098/rspb.2016.1902

Sunday, January 15, 2017

The hormonal basis for parental care in rattlesnakes

Pigmy Rattlesnakes, Sistrurus miliarius.
Rattlesnakes have been documented to show parental care, a complex social behavior that is widespread among vertebrates. This behavior has been linked to neuroendocrine regulation in mammals, and, to a lesser extent, birds and fish. However, its influence on reptiles is poorly known. In mammalian species and humans, the posterior pituitary hormones in the  oxytocin and vasopressin families mediate parental care behaviors. In a forthcoming paper in Biology Open, Lind et al. (2017) test the hypothesis that the regulatory role of posterior pituitary neuropeptides is conserved in a viviparous squamate reptile. The researchers pharmacologically blocked the vasotocin receptor in postparturient Pigmy Rattlesnakes, Sistrurus miliarius, and monitored the spatial relationship between females and their offspring relative to controls. Mothers in the control group demonstrated spatial aggregation with offspring, with mothers having greater postparturient energy stores aggregating more closely with their offspring. Blockade of vasotocin receptors eliminated evidence of spatial aggregation between mothers and offspring and eliminated the relationship between maternal energetic status and spatial aggregation. The results are the first to implicate posterior pituitary neuropeptides in the regulation of maternal behavior in a squamate reptile and are consistent with the hypothesis that the neuroendocrine mechanisms underlying social behaviors are broadly conserved among vertebrates.

Citation
Lind CM, Birky NK, Porth AM, Farrell TM. Vasotocin receptor blockade disrupts maternal care of offspring in a viviparous snake, Sistrurus miliarius. Biology Open. 2017 Jan 1:bio-022616.

Low cost method for surveying Eastern Massasauga Rattlesnake

Adult female Eastern Massasauga (Sistrurus catenatus). The rattle was painted with nail polish to 
aid with individual identification. Photo credit Danielle Bradke.
Monitoring populations of rare and endangered species is a priority for management and conservation. However, rare and endangered species have low detection probabilities. Low detection rates may be the result of small populations at low densities, misidentification, cryptic behavior, inefficiency of survey method and difficult survey conditions such as dense vegetation or weather. In a recent paper, Bartman et al. (2016)explored the effectiveness of using artificial cover objects (AOCs) and funnel traps to supplement visual survey methods for the Eastern Massasauga Rattlesnake (Sistrurus catenatus) at a site in southwestern Michigan. They found the funnel traps (2.64 snakes/h) were about six times more efficient than visual surveys (0.41 snakes/h) for capturing both sexes combined, and approximately 28 times more efficient for capturing males. Wooden coverboards (1.11 snakes/h) were approximately 3.5 times more efficient than visual surveys (0.32 snakes/h) for capturing females. The authors recommend the use of these trapping techniques, in addition to visual surveys, as efficient methods for capturing and monitoring Eastern Massasaugas.

Citation
Bartman JF, Kudla N, Bradke DR, Otieno S, Moore JA. 2016. Work Smarter, Not Harder: Comparison of Visual and Trap Survey Methods for the Eastern Massasauga Rattlesnake (Sistrurus catenatus). Herpetological Conservation and Biology 11:451-8.