Saturday, August 13, 2011

Viviparity in a Plesiosaurs


A specimen now displayed in NHM's Dinosaur Hall is the fossil of an embryonic 
marine reptile contained within the fossil of its mother. (Photo Credit: 
Natural History Museum of Los Angeles County).

A paper published 12 August 2011 in Science reports that Dr. F. Robin O'Keefe of Marshall University in Huntington, West Virginia and Dr. Luis Chiappe, Director of the Natural History Museum's Dinosaur Institute, have determined that a unique specimen now displayed in NHM's Dinosaur Hall is the fossil of an embryonic marine reptile contained within the fossil of its mother.

The 78-million-year-old, 15.4-foot-long adult specimen is a Polycotylus latippinus, one of the giant, carnivorous, four-flippered reptiles known as plesiosaurs that lived during the Mesozoic Era. The embryonic skeleton contained within shows much of the developing body, including ribs, 20 vertebrae, shoulders, hips, and paddle bones. The research by Dr. O'Keefe and Dr. Chiappe establishes that these dual fossils are the first evidence that plesiosaurs gave birth to live young, rather than hatching their offspring from eggs on land.

Although live birth (or viviparity) has been documented in several other groups of Mesozoic aquatic reptiles, no previous evidence of it has been found in the important order of plesiosaurs. Drs. O'Keefe and Chiappe have also determined that plesiosaurs were unique among aquatic reptiles in giving birth to a single, large offspring, and that they may have lived in social groups and engaged in parental care.

"Scientists have long known that the bodies of plesiosaurs were not well suited to climbing onto land and laying eggs in a nest," Dr. O'Keefe stated. "So the lack of evidence of live birth in plesiosaurs has been puzzling. This fossil documents live birth in plesiosaurs for the first time, and so finally resolves this mystery. Also, the embryo is very large in comparison to the mother, much larger than one would expect in comparison with other reptiles. Many of the animals alive today that give birth to large, single young are social and have maternal care. We speculate that plesiosaurs may have exhibited similar behaviors, making their social lives more similar to those of modern dolphins than other reptiles."

Plesiosaurs have no known living relatives, but were common in the world's oceans during the Age of Dinosaurs. They were among the top predators in the Western Interior Seaway, the vast, tropical body of water that split North America during the Cretaceous when waters from the Arctic Ocean and the Gulf of Mexico flooded onto the continent and met.

The remarkable NHM specimen was discovered in 1987 by Charles Bonner on the Bonner Ranch in Logan County, Kansas. Virtually complete except for parts of the adult's neck and skull, the "mother" specimen and her baby were given extensive conservation by NHM and then mounted for display by Phil Fraley Productions (Patterson, NJ) with the supervision of Drs. O'Keefe and Chiappe. The specimen is currently on display in the Dinosaur Hall, the new 14,000-square-foot exhibition at NHM featuring more than 300 fossils and 20 complete mounts of dinosaurs and sea creatures.

"Like many other specimens on display and in our collection, this extremely important specimen is among the significant fossils that can be admired and studied only here in Los Angeles," Dr. Chiappe stated. "We're very proud that at NHM, these irreplaceable materials are accessible not only to research scientists but to the public, giving people the opportunity to connect the quest for knowledge with the wonder of seeing the remains of these ancient and mysterious animals.

Citation
F. R. O'Keefe, L. M. Chiappe. Viviparity and K-Selected Life History in a Mesozoic Marine Plesiosaur (Reptilia, Sauropterygia). Science, 2011; 333 (6044): 870 DOI:10.1126/science.1205689

Monday, August 8, 2011

Snakes & Traffic

Roads have long been thought detrimental to snake populations, while at the same time roads provide insight into what species may be present in a given area. Two studies done in quite different part of the world and habitats suggest heavy traffic is damaging snake populations.
Black-tailed Rattlesnake, Crotalus molossus. JCM
Recently published results from a 27 year study (Jones et al., 2011) surveyed snake communities at two locations in the Sonoran Desert in south central Arizona. Both the Lower Colorado River Valley subdivision community south of Phoenix and the Arizona Upland subdivision community west of Phoenix were found similar in diversity and abundance with four species (Crotalus cerastes, C. atrox, C. scutulatus, and Rhinocheilus lecontei) accounting for 67–70% of all individuals at the two sites. The study consisted of 50 road-riding surveys yielding 175 snakes in 2,538 km (0.069 snakes per km) in the Lower Colorado River area and 80 road surveys in Upland areas west of Phoenix surveys, yielding 397 snakes in 6,391km (0.062 snakes per km) of roads. Of interest is the decline in snake numbers with dramatic increases in roadway traffic volume. The increase in traffic volumes from ~ 500 vehicles per day to over 3,000 vehicles per day at both of our sites was coincident with a decline in snakes found alive on the road, a finding quite similar to results obtained in a similar study of surveying for amphibians in North Carolina in relation to traffic volume. The amphibian study found almost twenty times as many amphibians were found on roads with less than 550 vehicles per day than with more than 2,000 vehicles per day.

In a second study done in Brazilian rainforest, over a shorter period of time Hartman et al (2011) sampled a 16 km tract of a paved road from October, 2001 to December, 2002, totaling 5,173 km. The most commonly found species were Chironius exoletus, C. bicarinatus, Oxyrhopus clathratus, and Chironius fuscus. They found 60 road killed snakes (0.0115 snakes per km), belonging to 15 species, representing about 58% of the species recorded for the region. Hartman et al. suggest the more mobile species seemed are more vulnerable to road mortality than sedentary species because species encountered dead on the road tended to be active foragers and show plasticity in microhabitat use. The high number of juveniles found in May could reflect juvenile recruitment. The increased road mortality in October may result from males searching females during the mating period.

Literature

Hartmann, P. A. et al. 2011. Snake Road Mortality in a Protected Area in the Atlantic Forest of Southeastern Brazil. South American Journal of Herpetology 6(1):35-42.

Jones, T. R. et al. 2011. Sonoran desert snake communities at two sites: concordance and effects of increased road traffic. Herpetological Conservation and Biology 6:61-71.

Sunday, August 7, 2011

Suzio Report - Tiger Rattlesnake Feeding

Twice in one day Herpers!                               5 August 2011

I'll bet that you can scarcely believe your good fortune.

According to the time stamp on my email program, Melissa Amarello checked in seven minutes after I sent the latest round of "Where's Waldo."
She not only found the snakes in that time period, she yanked out her high tech magic marker, circled them all., and shipped them back to me.
Quick with the eyes and quick on the draw, that's our Cerbermissy.

NOW I'M MAD AS HELL. NEXT TIME, WE TAKE OFF THE KID GLOVES.
NO MORE E-Z WALDOS FOR YOU GUYS!!

Five times in my life I have walked by animals that were gyrating in their last death throes. Twice it was very young cottontail rabbits, one of which was screaming a high-pitched death song. Once, it was a spiny lizard, once it was a K-rat, and once, it was little birdie. In all cases, I suspected a snake bite, and in all cases, I just kept moving. In all five cases, the prey items were gone on my return trip. This is the high price of impatience.

We've got a herper here in Arizona who has the patience of Job.
(Job [pronounced "Jobe"] is a guy in the bible who would not relinquish his faith in God, despite the fact that God was allowing Satan to mess with him mightily.
At one point, while Job is dripping pus from every orifice in his body, and dogs are licking his wounds,his wife encourages him to "curse God and die."
But Job wouldn't do it. THAT'S patience........)

Ok, the Sunday Skool lesson is over.

On the evening of 23 July, Jeff "Job" Smith spotted a pocket mouse behaving erratically on the north berm of our beloved Suizo Wash plot. Lesser men would have done a Roger Repp, and kept moving. But not Jeff. He plunked his scrawny a$$ down in the sand, set up his video camera, and waited there like a photographic buzzard to film what would happen next. We were also blessed to have Melissa Amarello, Mats and Karl Hoggren, Bill Montgomery, Hans-Werner Herrmann, Ryan Sawby as witnesses, and I came along when it was all half over to document what came next. Gordon Schuett was out there somewhere, doing what the rest of us were SUPPOSED to be doing. Namely, finding new snakes for our study.

Jeff has the whole sequence on film, and was kind enough to post it on M+J's most excellent website. Here is the link to that:


Bill Montgomery was also kind enough to shoot some images of the action, which are self-explanatory
enough to rock on without further commentary. Right after the swallowing, our newest tiger rattlesnake
was bagged, and thanks to the surgical skills of Dr. Dale DeNardo, is now gaily slithering the wash
seeking new furry friends.


Best to all, roger

Friday, August 5, 2011

Suizo Report -- Where's Waldo?

Howdy Herpers, 5 August 2011

Back when we were all much younger, typing boy here sent out a Steve Barten image of a young Arizona Black Rattlesnake cryptically coiled somewhere within its framework. Many of you were on that snake like stink on a monkey. It amazed me how good some of you were at the game of spotting a snake that you had no business seeing.

We used the cartoon character "Waldo" of "Where's Waldo?" fame to spark the search images of the all American herper crowd. It never occurred to me that people wouldn't know who the hell Waldo is. It must have indeed been a mystery to some of our foreign guests. (That's right, dudes and dudesses, these emails cross oceans. Please join me in giving a big, world wide Arizona howdy to Japan, Germany, Switzerland, Sweden, and Australia.)

I would not have our foreign guests be ignorant of the great American tradition of Where's Waldo. So I'm going to explain it a little bit, so that ya'll will understand what it is I'm talking about.

Waldo is nerdy-looking dude who wears a red-striped shirt, a red stocking hat, thick glasses, and is scrawny of build. He hangs out in crowded places, and despite his brightly colored shirt and hat, he blends in well with his surroundings. For about five bucks, you buy a book that has about 20 scenes with Waldo in them, and you try to find the dude. Maybe some people have trouble finding Waldo. But he is absolutely babyshit under the baleful eye of herpers. No problem, we can find Waldo. I'm just not sure why would wish to look for him, when there are snakes to be found.

If you wish to know more about Where's Waldo, just type his hallowed name into your favorite search engine. He's there, waiting for you.

Back in the early days of my association with rattlesnakes, Dr. Dave Hardy Sr. made a comment that had me all sorts of perplexed. He was before an aggregation of herpers, discussing his radio-tracking study on Black-tailed Rattlesnakes. The statement he made was "No matter how good you are, you only see the obvious snakes." This had me all sorts of bent, because I thought I was seeing them all. It wasn't until I started radio tracking myself that I saw the light of Dr. Hardy's statement. It is hard to imagine any animal in the same size class that can hide better than a snake!

Before we launch into the next round of Where's Waldo in the snake world, I just wanted to say that there is no need to respond to this email. You don't get any prize for finding the snakes. But you do get the satisfaction of knowing that you can still hang with the great ones--if you know any. Next week, I will send out images that show where the snakes are.

Without further adieu, Where's Waldo?

Image 1: If you can't find the Sidewinder in the picture, I suggest that you give up now. You couldn't find your butt if it had a bell on it!

Image 1: If you can't find the Sidewinder in the picture, I suggest that you give up now. You couldn't find your butt if it had a bell on it!



Image 2: Ok hotshots, you made it through the first image. Way to shine! The head and a bit of flank of an Arizona Black Rattlesnake is visible in this image.

Image 3: Wow! You guys are GOOD. Feast your eyes on this Western Diamondback rattler amongst some hackberry, if you can! Roughly 80% of the snake is visible in this one.

Image 4: And last, but not least, the same diamondback is now under catclaw--ouchie oochie. About 60% visible.

Ok, these were all too easy. NEXT TIME, we'll play just a little bit rougher.

Best to all, roger

New Montana State Research Sheds Light on South Pole Dinosaurs

BOZEMAN, Mont. – Dog-sized dinosaurs that lived near the South Pole, sometimes in the dark for months at a time, had bone tissue very similar to dinosaurs that lived everywhere on the planet, according to a doctoral candidate at Montana State University.

That surprising fact falsifies a 13-year-old study and may help explain why dinosaurs were able to dominate the planet for 160 million years, said Holly Woodward, MSU graduate student in the Department of Earth Sciences and co-author of a paper published Aug. 3 in the journal "PLoS ONE."

"If we were trying to find evidence of dinosaurs doing something much different physiologically, we would expect it to be found in dinosaurs from an extreme environment such as the South Pole," Woodward said. "But based on bone tissues, dinosaurs living within the Antarctic Circle were physiologically similar to dinosaurs living everywhere else.

"This tells us something very interesting; that basically from the very start, early dinosaurs, or even the ancestors of dinosaurs, evolved a physiology that allowed an entire group of animals to successfully exploit a multitude of environmental conditions for millions of years," Woodward said.

Jack Horner, Woodward's adviser and Regents Professor of Paleontology/Curator of Paleontology at MSU's Museum of the Rockies, said Woodward's findings are consistent with other results from the museum's histology lab.

"I think the most important finding is that polar dinosaurs don't seem to be any different than any other dinosaurs in respect to how their bones grew," Horner said. "Dinosaurs have annual growth lines and those that don't have them are simply not yet a year old."

Woodward said she conducted her research after reading a 1998 study about polar dinosaurs. Intrigued by the study, she decided to review the findings and received a National Science Foundation grant that allowed her to travel to Australia last summer, set up a histology laboratory and analyze bones in a rare collection in Australia's Melbourne Museum.

Woodward analyzed the bone tissue of 17 dinosaurs that lived 112 to 100 million years ago during the latter part of the Early Cretaceous Period. All but one of the dinosaurs in her study were plant eaters. All lived in the Antarctic Circle in what is now known as the Australian state of Victoria.

Also participating in the study were the authors of the original study: Anusuya Chinsamy at the University of Cape Town in South Africa, Tom Rich at the Melbourne Museum and Patricia Vickers-Rich at Monash University in Australia.

The three scientists who conducted the original study welcomed her analysis and didn't mind that she falsified their hypothesis, Woodward said. She added that the new study looked at more dinosaur bones than the original study because more bones from the polar dinosaurs were available. Paleontologists have been adding to the collection over the past 25 to 30 years.

The original study looked at the bone microstructure of the polar dinosaurs and concluded that the differences they saw indicated that some dinosaurs survived harsh polar conditions by hibernating, while others evolved in a way that allowed them to be active year-round, Woodward said.

The new study showed that all but the youngest dinosaurs had "Lines of Arrested Growth" or LAGs, Woodward said. Since the hibernation hypothesis was based on the presence or absence of LAGs, the new study falsified the hypothesis.

LAGSs, in a bone cross section, look like tree rings, Woodward said. Like tree rings, they are formed when growth temporarily stops.

"Research on animals living today suggests that LAGs form annually, regardless of latitude or climate," Woodward said. "Like tree rings, LAGs can be counted to age an animal, so that the absence of these marks likely indicates a dinosaur was less than a year old. These marks have also been found in dinosaurs that lived at much lower latitudes having no need to hibernate."

The new study doesn't mean there was nothing unique about polar dinosaurs, but those qualities aren't apparent in bone tissue, Woodward said.

"It is very likely that dinosaurs living in different environments evolved specific adaptations – either physical or behavioral – to cope with environmental conditions," she said. "Analysis of bone microstructure can tell us a great deal about growth, but some things just aren't recorded in bone tissue."

Protected Geography Fails to Slow Decline in Biodiversity

Protected habitat has increased dramatically over the past 40 years yet the rapid decline in biodiversity continues. Seven million square miles of terrestrial habitat and one million square miles of ocean have been protected since 1960. Camilo Mora and Peter F. Sale have documented the problem in Marine Ecology Progress Series. Despite the number and size of protected areas the diversirty of terrestrial and marine species continues to decline during this 40 year period. Protecting land and water is a common conservation strategy worldwide, but it has failed to prevent the steady disappearance of the planets creatures. The following is an edited version of a Huffington Post article by Tom Zeller. The full article can be found here.
"The problem is bigger than one we can realistically solve with protected areas -- even if they work under the best conditions," said Camilo Mora, an assistant professor in the Department of Geography at the University of Hawaii at Manoa and lead author of the study. "The protected area approach is expensive and requires a lot of political and human capital," Dr. Mora continued in an email message to The Huffington Post. "Our suggestion is that we should redirect some of those resources to deal with ultimate solutions."
The steady loss of biodiversity -- defined roughly as the rich variety of living things -- can, in turn, have profound implications for human civilization, which relies on healthy, variegated ecosystems to provide a host of ecological services from water filtration and oxygen generation to food, medicine, clothing and fuel.

The precise value of such services is difficult to quantify, but one economic analysis estimated they were worth as much as $33 trillion globally.

While the study concedes that individual protected areas that are well-designed and well-managed can be successful in preventing the imminent extinction of species and ecosystems, a variety of other forces conspire to further reduce biodiversity overall.
"Protected areas, as usually implemented, can only protect from over-exploitation, and from habitat destruction due to exploitation and other direct human actions within their borders. They are a tool for regulating human access and extraction," said Peter F. Sale, assistant director of the United Nations University Institute for Water, Environment and Health, and the study's co-author. "Biodiversity loss is also caused by pollution, by arrival of invasive species, by decisions to convert habitat to other uses -- farms, villages, cities -- and by various components of climate change," he told HuffPost. "None of these are mitigated by the creation of protected areas except, possibly, the removal of habitat to other uses."
In other words, the researchers, who based their analysis on a broad range of global data and a review of existing literature, suggest that the implementation of habitat protection is unable to keep pace with other stressors contributing to species loss overall.
This is partly due to lack of enforcement. Only about 5.8 percent of terrestrial protected areas and 0.08 percent of marine sanctuaries see reliable and consistent enforcement.
Further, the authors note most research suggests that between 10 percent and 30 percent of the world's ecosystems need to be protected to preserve optimal biodiversity. But despite what appears to be a rapid increase in protected lands, the pace is too slow to achieve those targets anytime soon. On land, the 10 percent target, under the best of circumstances, would not be reached until 2043, the study estimated. The 30 percent target would not be achieved until 2197. The same target percentages for marine sanctuaries would be reached by 2067 and 2092, respectively.
And these projections are almost certainly too optimistic, the authors note, because the rate of establishment of new protected areas would be expected to slow considerably as conservation efforts runs up against the needs of a rapidly expanding human population.
Global population is expected to pass 7 billion in Octoberaccording to new estimates from the population division of the Department of Economic and Social Affairs at the United Nations. That's an increase of 1 billion people in about a dozen years.

Other challenges include the size of protected areas -- which are often too small for larger species to survive -- and the lack of connectivity between protected areas, which is needed for healthy genetic dispersal.
The authors of Thursday's analysis suggest that reversing biodiversity losses will require a vast rethinking of conservation strategy -- one that redirects limited resources toward more holistic solutions. 

Thursday, August 4, 2011

Nag Panchami 2011

The Times of India is reporting the following story today, August 4, 2011.

KERI: Among the reptiles, snakes are the most misunderstood. They incur the wrath of the public and are killed as they are venomous. The common cobra is the most poisonous and even a bite can be fatal if timely and appropriate treatment is not taken.

Ironically, though the common cobra is venomous, people from various parts of India worship it as a deity. The fifth day of Shravan in the Hindu calendar is celebrated as Nag Panchami and is associated with the worship of clay idols of cobras in many Hindu houses across Goa.

The Avakhale families of Virdi in Bicholim and Shet families in Kumbharjuve eat vegetarian food on the occasion of Nag Panchami, but do not worship clay cobra idols.

The Desai families in Kothambi, Quepem, visit the temple on this day, and worship a clay idol of a snake kept there.

"Our family does not worship an idol, but a picture of a cobra is drawn on a banana leaf with turmeric paste," says Gayatri Damle from Khaiti of Kasarpal in Bicholim.

In Caranzol, Sattari, at the temple of Shantadurga, folk deity Brahmani has a hooded cobra on both of her sides. However, despite the deity's affinity to the snake god and Lord Shiva always shown with a cobra, some Hindu families do not celebrate the festival. They don't worship clay idols of cobras believing that their ancestors would eat cobras made from flour.

In the past, there was a tradition of making a snake idol from kneaded flour. When there was nothing to eat for the festival, some families would satisfy their hunger by eating the cobras made out of the flour.

Suchita Shet from Gholwada- Kumbharjuve, says, "It is believed that once, a cobra ate a certain dish prepared from shevyo (vermicelli). Hence, our families do not worship the clay idol of the cobra."

Among those who do celebrate the festival, there are certain taboos associated with Nag Panchami day. People do not dig in soil and no one plucks mushrooms as the ant hill is considered to be the abode of the cobra.

Tuesday, August 2, 2011

Amphibian Phylogeny Revised

Siren intermedia. JCM
Pyron and Weins have a new amphibian phylogeny that is now available on-line, prior to publication. No previous amphibian phylogeny used more than 522 species. However, other studies used limited taxon sampling and generated large numbers of partially overlapping sequence data for many species. The authors combine these data and produce a novel estimate of extant amphibian phylogeny, based on 2871 species (about 40% of living species) from 432 genera (85% of the 500 living genera). Species sampled averaged 2563 bp per species. The data set provides strong support for many groups recognized in previous studies, but it also suggests non-monophyly for several currently recognized families, particularly in hyloid frogs (e.g., Ceratophryidae, Cycloramphidae, Leptodactylidae, Strabomantidae). To correct these the authors provide a revised classification of extant amphibians for taxa traditionally delimited at the family and subfamily levels. The new phylogeny includes several new families, strongly supported by their data, but not recognized in current classifications (e.g., Alsodidae, Batrachylidae, Rhinodermatidae, Odontophrynidae, Telmatobiidae). Some highlights include the following. Within caecilians their results agree with other recent studies in supporting clades corresponding to Rhinatrematidae, Ichthyophiidae, and Caeciliidae, but the traditional family-level classification of caecilians that is used by Amphibia Web, (2011) was not supported by this study and they found the caeciliid subfamily Typhlonectinae to be paraphyletic. Within salamanders, the family and subfamily-level relationships were found to be  mostly consistent with most recent model-based molecular analyses and current classifications availabe on Amphibia Web and at Amphibian Species of the World web sites. However, they found strong support for a sister-group relationship between Sirenidae and all salamanders exclusive of Cryptobranchidae and Hynobiidae. Within frogs, the Hyloidea are several families were found not to be monophyletic: Ceratophryidae, Cycloramphidae, Leptodactylidae, and their solution is to recognizing several additional families relative to current classifications (Alsodidae, Batrachylidae, Odontophrynidae, Rhinodermatidae, Telmatobiidae) and synonymizing one (Strabomantidae with Craugastoridae). These newly recognized families are either re-definitions of previously recognized families (Rhinodermatidae,Telmatobiidae), or elevation of existing taxa presently below family rank (Alsodinae, Batrachylinae, Odontophrynini) to the rank of families. The study also provides evidence that the supermatrix approach provides an effective strategy for inferring large-scale phylogenies using the combined results of previous studies, despite many taxa having extensive missing data.

Citation
R. Alexander Pyron and John J. Wiens   2011. (in press) A large-scale phylogeny of Amphibia including over 2800 species, and a revised classification of extant frogs, salamanders, and caecilians. Molecular Phylogenetics and Evolution doi:10.1016/j.ympev.2011.06.012.

Attempted Predation on the Common Marmoset by a Lancehead

The Callitrichidae are dwarf lineage or arboreal primates commonly known as marmosets, tamarins, and lion tamarins that evolved in the Amazon Basin where rivers are biogeographic barriers. Their small size makes them particularly vulnerable to snakes. Ferrari and Beltrão-Mendes (in press, 2011) describe a juvenile common marmoset (Callithrix jacchus) attacked by a whitetail lancehead, Bothrops leucurus. The juvenile was playing with others close to the ground when the snake struck. The attack was almost immediately fatal, the juveile was dead within seconds of envenomation. However, the snake was unable to ingest the body of the marmoset, and after 10 min the viper abandoned the body. The authors note that raptors are usually considered the principal predators of callitrichids, but that their record reinforces vulnerability of these primates to snakes. Juveniles and infants may be at higher risk when distracted by play. Snakes have undoubtedly been an important slection factor during primate history.

Citation
Ferrari, S. F. and R. Beltrão-Mendes. 2011 in press. Do snakes represent the principal predatory threat to callitrichids? Fatal attack of a viper (Bothrops leucurus) on a common marmoset (Callithrix jacchus) in the Atlantic Forest of the Brazilian Northeast. Primates DOI: 10.1007/s10329-011-0260-8

Monday, August 1, 2011

Rapid Evolution in Island Frogs

Fanged frog guarding eggs. Photo credit:
Jimmy A. McGuire
Scientists led by Ben Evans of McMaster University have documented the rapid evolution of new fanged frog species on the island of Sulawesi, near the Philippines. The team found 13 species of fanged frog on the island, nine of which hadn't previously been described. The species differ in body size, amount of webbing in their feet, and even how they raise their young—all in accordance with the demands of their distinct ecological niches. Sulawesi has the same number of fanged frog species as the Philippine archipelago. "We would expect to find more species on the archipelago because it's so much larger, but that's not the case," Evans said. Why such diversity on the smaller island? There's less competition on Sulawesi, the researchers say. Fanged frogs in the Philippines have to compete with another genus of frogs, Platymantis. Platymantis never made to hop over to Sulawesi, leaving the fanged frogs free to spread out into new habitat niches, to which they eventually adapted. The rapid evolution of these frogs is a striking example of adaptive radiation—a concept Charles Darwin famously recorded in Galapagos finches.

Mohammad I. Setiadi, Jimmy A. McGuire, Rafe M. Brown, Mohammad Zubairi, Djoko T. Iskandar, Noviar Andayani, Jatna Supriatna, Ben J. Evans. Adaptive Radiation and Ecological Opportunity in Sulawesi and Philippine Fanged Frog (Limnonectes) Communities. The American Naturalist, 2011; 178 (2): 221 DOI:10.1086/660830

Rediscovery of a Remarkable Caecilian

Boulengerula fischeri. Photo credit G. John Measey
The fossorial herpetofauna remains one of nature's best gaurded secrets. Many fosrorial snakes, lizards, and caecilians remain to be discovered and their natural history investigated. The African caecilian Boulengerula fischeri was described from a single specimen deposited onto a car by an unknown collector in 1987, and no further specimens were collected - until recently. Measey et al. (2011) describe a collection of 20 specimens taken from soil under banana trees, in an area immediately outside Cyamudongo Forest in southwestern Rwanda, about 3 km from the type locality. Adults reach a maximum length of nearly 400 mm but are only 4.5 mm wide.

Saturday, July 30, 2011

Raptors Avoid Snakes With Triangular Heads

Vipera latastei gaditana. Photo courtesy of Harold van der Ploeg.
Looking like a venomous species can have advantages for mimics, and a triangular-shaped head similar to that found in many vipers may convey a message to predators that says I am dangerous. Janne K. Valkonen, Ossi Nokelainen, and Johanna Mappes tested this idea using snake modles made of non-toxic grey plasticine. Four different kinds of artificial snakes were used: 1) zigzag-patterned snakes with triangular (viper type) heads and 2) with narrow (colubrid type) heads and 3) plain (grey) snakes with triangular heads and 4) with narrow heads. The use of plain snakes was crucial to separate the effect of the head shape from the overall appearance of vipers. The length and diameter of artificial models were identical in all treatments and in correspondence to the size Vipera latastei gaditana. The experiment was conducted in Coto Doñana National Park, southern Spain. Six transects were conducted in 2009 and thirteen in 2010 and a total of 595 snake models were used. The replicas were placed on the natural background in random order at approximately 15 metre (15 paces) intervals following features of the terrain. The authors found a a significant difference in the number of raptor attacks among treatments. Plain snakes with narrow heads were attacked significantly more often by raptors than were plain snakes with triangular heads. There was no difference in the number of raptor attacks on patterned, triangular-headed snake replicas and on patterned replicas with narrow heads. When attack data was pooled on snake replicas based on their patterns, plain snakes were attacked by raptors significantly more frequently than were zigzag patterned replicas. 8.2% of the 595 snake replicas were attacked by raptors and 18.5% by mammalian predators. Attacks by mammalian predators did not differ between treatments.

Citation: Valkonen JK, Nokelainen O, Mappes J (2011) Antipredatory Function of Head Shape for Vipers and Their Mimics. PLoS ONE 6(7): e22272. doi:10.1371/journal.pone.0022272

Thursday, July 28, 2011

Saving Amphibian Diversity by Mitigating Bd

A new article by Woodhams et al. suugests that amphibian diversity can be resuced from the emerging chytrid fungus Batrachochytrium dendrobatidis (Bd). The fungus can exist in amphibians populations as a transient commensal to lethal pathogen. And they suggest a combined strategy of halting pathogen spread and developing survival assurance colonies, as well as prophylactic or remedial disease treatment. Epidemiological models of Bd suggest that mitigation strategies can control disease without eliminating the pathogen. Sustainable conservation of amphibians in nature is dependent on long-term population persistence and co-evolution with potentially lethal pathogens. Therefoe the authors suggest that disease mitigation not focus exclusively on the elimination or containment of the pathogen, or on the captive breeding of amphibian hosts. Instead, successful disease mitigation must be context specific with epidemiologically informed strategies to manage already infected populations by decreasing pathogenicity and host susceptibility. A three step treatment for populations is proposed: first, identify mechanisms of disease suppression; second, parameterize epizootiological models of disease and population dynamics for testing under semi-natural conditions; and third, begin a process of adaptive management in field trials with natural populations. Below is one of the figures from the artlcle.
Some of the rediscovered species in Costa Rica including. A. Craugastor ranoides, B. Atelopus varius, C. Lithobates vibicarius, and D. Pristimantis lemur. Locality data are retained to discourage poaching. E. Climatic refuge in Costa Rica indicated by arrow. The core distribution of Batrachochytrium dendrobatidis (Bd)occurs in humid environments and coincides with the distribution of most declining populations of amphibians. Low abundance relict populations are being rediscovered within Bd enzootic zones, often with subclinical infections. Other species are found outside Bd enzootic zones. Healthy populations, in which a susceptible species maintained high abundance, were found at the edge of the distribution of the robber frog, Craugastor ranoides, in a climatic refuge [138]. Puschendorf et al. ([139]; including details of the bioclimatic model pictured in E) hypothesized that this relict population in the dry forest of Santa Elena Peninsula, Costa Rica, survives because climatic conditions in that habitat make pathogen establishment or persistence on hosts less likely.

Locomotion in Early Reptiles

Modern scientists would have loved the sight of early reptiles running across the Bromacker near Tambach-Dietharz (Germany) 300 million years ago. Unfortunately this journey through time is impossible. But due to Dr. Thomas Martens and his team from the Foundation Schloss Friedenstein Gotha numerous skeletons and footprints of early dinosaurs have been found and conserved there during the last forty years. "It is the most important find spot of primitive quadruped vertebrates from the Perm in Europe," says Professor Dr. Martin S. Fischer from the University Jena (Germany). The evolutionary biologist and his team together with the Gotha scientists and other partners are now starting a research project not only to analyze the locomotion of these primeval saurians. They also want to set them back into motion - at least in animation. The Volkswagen Foundation (VolkswagenStiftung) will support the project with about 288.000 Euro during the next two years. "Our first major palaeontologic project", as zoologist Fischer delightedly calls it. 
Heloderma suspectum. JCM
 How did the locomotion system of amniotes change?

The fossils found on the Bromacker date back to the oldest fully terrestrial vertebrates. These so-called amniotes are the first real "land-dwelling animals". This became possible through a first evolutionary step in which they laid a completely encapsulated egg in whose 'watery inside' the offspring could develop. Therefore tadpoles and gills became redundant. "The Bromacker fossils are the closest relatives of the last mutual ancestor of the amniotes that have been found so far," Dr. John A. Nyakatura, who oversees the new research project points out, stressing the evolutionary-biological importance of the finds. How did the locomotion system of those amniotes change? They are according to Nyakatura "pivotal to the genealogical tree for evolutionary biologists". The Jena expert in locomotion research says the crucial questions of the new project are: "Which functionally anatomical consequences does 'cutting the cord' to water have for the locomotion system of the animals?"

The Jena zoologists and their partners in Gotha, Dresden (both Germany), England and the USA wanted to find out. In their research they cannot only rely on years of expertise but also on one of the fastest X-ray video systems worldwide, which is used at the Friedrich Schiller University. With the help of this system, Dr. Nyakatura and the Paleo-Biomechanist Dr. Vivian Allen who will change from London to Jena in autumn, plan to analyze the locomotion systems of diverse animals resembling the early reptiles. They will observe skinks, tiger salamanders, green iguanas and small crocodiles. In order to do so the animals will move on a treadmill in front of the X-ray video camera that can take up to 2.000 pictures per seconds. Moreover the pressure on the joints will be investigated and footprints will be generated on wet clay. At the end of these analysis a comprehensive locomotion profile of the species is to be created - which in itself will bring science forward.

Three-dimensional, animated reconstructions of the fossil skeletons

The protocol of the footprints will then be compared to the primeval footprints, in order to get an understanding of the early saurians movements. "And this in turn will allow conclusions to be drawn about the find spot and what happened there," Dr. Martens adds. This is only possible because the Gotha researchers could not only recover numerous footprints but also complete skeletons of unique quality. "The fossils are mind-blowing," Nyakatura stresses. The entire animal relics encapsulated in stone slabs are being scanned with the help of the TU Dresden in order to create three-dimensional reconstructions of the skeletons. At the end of the project animated studies of the early saurians will be generated from the scans and the locomotion protocols. "Thanks to the support of the VolkswagenStiftung and the co-operation with the University Jena we will finally be able to give an insight into the world of the early saurians to the visitors of the 'Museum of Nature' in Schloss Friedenstein," says Dr. Martin Eberle, director of the Foundation Schloss Friedenstein Gotha. Now the researchers are hoping their project will be successful so that they cannot only mount an exhibition on the subject in two years' time. They will also be able to travel 300 million years back in time due to the innovative animations - and they will watch the early reptiles running.

Tuesday, July 26, 2011

Turtles + Lizards Form A Clade?

Famous for their sluggishness, turtles have been slow to give up the secrets of their evolution and place on the evolutionary tree. For decades, paleontologists and molecular biologists have disagreed about whether turtles are more closely related to birds and crocodiles or to lizards. Now, two scientists from the Mount Desert Island Biological Laboratory in Bar Harbor, Maine, and their colleagues from Dartmouth College and Harvard and Yale Universities have developed a new technique using microRNAs for classifying animals, and the secret is out. Turtles are closer kin to lizards than crocodiles.

To reach their conclusion, published in Nature News and Biology Letters, the research team looked at a newly discovered class of molecules called microRNA. Most of the genetic material or DNA that scientists study provides the code for building proteins, large molecules that form an essential part of every organism. But microRNAs are much smaller molecules that can switch genes on and off and regulate protein production. They are also remarkably similar within related animal groups and provide important clues for identification.

“Different microRNAs develop fairly rapidly in different animal species over time, but once developed, they then remain virtually unchanged,” said Kevin Peterson, a paleobiologist at MDIBL and Dartmouth College. “They provide a kind of molecular map that allows us to trace a species’ evolution.”

Peterson worked with Ben King, a bioinformatician at MDIBL. “My role in the study was to enhance our software so we could find new and unique microRNAs in the lizard genome,” King said. “We identified 77 new microRNA families, and four of these turned out to also be expressed in the painted turtle. So we had the evidence we needed to say that turtles are a sister group to lizards and not crocodiles.”

Though few creatures have been as puzzling as the turtle, the research team plans to use its microRNA analysis on other animals to help determine their origins and relationships as well. It is also developing a web-based platform to share the software with other researchers around the world.

In addition to King and Peterson, the research team included Tyler Lyson and Jacques Gauthier from Yale University, Eric Sperling from Harvard University, and Alysha Heimberg from Dartmouth College.

Citation
Tyler R. Lyson, Erik A. Sperling, Alysha M. Heimberg, Jacques A. Gauthier, Benjamin L. King and Kevin J. Peterson. 2011. MicroRNAs support a turtle + lizard clade. Biology Letters doi: 10.1098/rsbl.2011.0477.