Tuesday, July 30, 2013
Snakebite is one of the most neglected of tropical diseases—the number of fatalities is comparable to that of AIDS in some developing countries. It has been estimated that 75% of snakebite victims who die do so before they ever reach the hospital, predominantly because there is no easy way to treat them in the field. Antivenoms provide an imperfect solution for a number of reasons—even if the snake has been identified and the corresponding antivenom exists, venomous bites often occur in remote locations far from population centers, and antivenoms are expensive, require refrigeration, and demand significant expertise to administer and manage.
“In addition to being an occupational hazard for field scientists, snakebite is a leading cause of accidental death in the developing world, especially among otherwise healthy young people,” says Lewin, the Director of the Center for Exploration and Travel Health at the California Academy of Sciences. “We are trying to change the way people think about this ancient scourge and persistent modern tragedy by developing an inexpensive, heat-stable, easy-to-use treatment that will at least buy people enough time to get to the hospital for further treatment.”
In his role as Director of the Academy’s Center for Exploration and Travel Health, Lewin prepares field medicine kits for the museum’s scientific expeditions around the world and often accompanies scientists as the expedition doctor. In 2011, Lewin put together snakebite treatment kits for the Academy’s Hearst Philippine Biodiversity Expedition, which would have required scientists to inject themselves if they needed treatment. When he saw their apprehension about the protocol, Lewin began to wonder if there might be an easier way to treat snakebite in the field.
In some fatal snakebites, victims are paralyzed by the snake’s neurotoxins, resulting in death by respiratory failure. A group of common drugs called anticholinesterases have been used for decades to reverse chemically-induced paralysis in operating rooms and, in intravenous form, to treat snakebite when antivenoms are not available or not effective. However, it is difficult to administer intravenous drugs to treat snakebite outside of a hospital, so Lewin began to explore the idea of a different delivery vehicle for these antiparalytics—a nasal spray.
In early April of 2013, Lewin and a team of anesthesiologists, led by Dr. Philip Bickler at UCSF Medical Center, designed and completed a complex experiment that took place at the medical center. During the experiment, a healthy human volunteer was paralyzed, while awake, using a toxin that mimics that of cobras and other snakes that disable their victims by paralysis. The experimental paralysis mimicked the effects of neurotoxic snakebite, progressing from eye muscle weakness all the way to respiratory difficulty, in the same order as is usually seen in envenomation. The team then administered the nasal spray and within 20 minutes the patient had recovered. The results of this experiment were published online in the medical journal, Clinical Case Reports.
Later in April, Lewin delivered one of the keynote addresses, titled “How Expeditions Drive Clinical Research,” at the American Society for Clinical Investigation/Association of American Physicians joint meeting in Chicago, during which he talked about this experiment and its origins. As a result, he met Dr. Stephen Samuel, an Indian physician and scientist from Trinity College Dublin who was interested in collaborating in India, where an estimated 1 million people are bitten by snakes every year, resulting in tens of thousands of deaths. Lewin flew to India to help Samuel set up treatment protocols at a rural hospital in Krishnagiri.
In late June, Samuel, Dr. CS Soundara Raj and colleagues at TCR Multispeciality Hospital in Krishnagiri, Tamil Nadu, India treated a snakebite victim using this method. The patient was suffering from persistent facial paralysis from a krait bite, despite having undergone a full course of antivenom treatment. Upon treatment with the antiparalytic nasal spray, the facial paralysis was reversed within 30 minutes. Two weeks after being treated, the patient reported having returned to her daily activities.
Lewin and his colleagues in the United States are now conducting additional studies on mice to develop new methods and drug combinations, as there are many combinations of anticholinesterases and anticholinergic agents that could be tried to make delivery of the drugs more predictable through the mucous membranes in the nose or eyes. He is also working to set up future clinical studies with Samuel, Soundara Raj and their colleagues in India. While there is much work in front of them, they have already taken important steps toward addressing a major global need. The entire team has embraced the TCR Multispeciality Hospital motto that “no patient should die from snakebite.”
Matthew R. Lewin, Philip Bickler, Tom Heier, John Feiner, Lance Montauk, Brett Mensh. Reversal of experimental paralysis in a human by intranasal neostigmine aerosol suggests a novel approach to the early treatment of neurotoxic envenomation. Clinical Case Reports, 2013; DOI: 10.1002/ccr3.3
Sunday, July 28, 2013
|Photo credit Bill Bouton.|
However, some environmentalists have taken the route of considering virtually everything endangered, this only dilutes the discussion with misinformation and results in a decline in credibility, a problem recently discussed the Onion
And of course, once something is listed as threatened, endangered, or placed on a CITES list it automatically becomes more difficult for science to study it.
In Pembroke, British Colombia, environmentalists are picking a battle with a developer, they probably can't win. They are attepting to use the sharp-tailed snake, Contia tenius, a threatened species to slow or halt the development of Sunshine Ridge.
The developer describes the community this way:
"The Pemberton Benchlands are set among the evergreens, overlooking the Pemberton Valley. Available home sites will enjoy spectacular views of majestic Mt. Currie, the lush valley farm lands and the surrounding mountain vistas... Pemberton is still the fastest growing community in BC, which makes it both the ideal place to move to and invest."
The environmentals have a different view point. One resident writes,
"This side of Pemberton will be blasted a bit more and will show a start of our planet cancer: high-density housing. How many people is this going to bring over the next 25 years? Twenty-five hundred to 3,000 units on the plans — maybe over 5,000 people, 2,000 dogs (at least) and cats will be chasing wildlife on the MacKenzie Ridge (you can say goodbye to the endangered species like the sharp tail snake). Commercial zoning, hotel resort on the edge of Mosquito Lake, tourism accommodation between the two lakes. This place is more conducive to a tent."
The local newspaper, the Question, reports that a local environmental organization, the Stewardship Pemberton Society (SPS) was recently successful in securing a grant from the Habitat Conservation Trust Fund in an effort to assist the Village of Pemberton in developing a policy for species-at-risk in large development permit areas.
Apparently this was in direct response to the discovery of the sharp-tailed snake in Pemberton in 2011 within one kilometre of the proposed Sunstone Ridge development. When council approved that Development Permit in February 2012, it was under the condition that snake habitat mitigation plan be implemented.
"Veronica Woodruff of the SPS reported to council during Tuesday’s (July 23) meeting that since beginning an inventory, 10 more of the Sharp-tailed snakes have been found in the Pemberton area.
“I am not a person that is against development,” said Woodruff. “But I do believe that construction can be done in a partnership and it can benefit both the species and the development.”
"Woodruff cited examples of snakes coexisting on residential properties in parts of Victoria and the Sunshine Coast islands.
“It's really working proactively with the developers to talk about what we know about the snakes and some ideas on layout, construction mitigation and potential leave areas for these kinds of species.”
"When Coun. Mike Richman asked what the next step would be in working with the Sunstone Ridge developers, Woodruff replied:
“We know the preferred types of habitats. It's literally an exercise in Google Earth, looking at the substrate and saying 'OK, it's likely this will be a good nesting and birthing area.' If that's an area that's slated for development, take the time, pull it apart and see what's there or consider leaving that area and tweaking the development.
"But development is not the only concern for the snakes. Several sightings have occurred on mountain bike trails, with one snake being found dead on Happy Trail after being run over by a mountain bike. Woodruff brought in a large sample of a sign to be mounted near bike trails that read “Brake for Snakes!
"The SPS will be reporting its final inventory of the Sharp-tailed snakes in September."
In 1960, Sherburne Cook, wrote a short note in Herpetologica (16(3):163-167) on Contia tenius, he wrote "C. tenius is not the rare species previously supposed but perhaps locally one of the more common species on the West Coast...Furthermore, the range, ecological distribution, and behavior of this snake appear to be closely correlated with a highly utilized food resource - an introduced genus of slug."
In 2010 Feldman and Hoyer (Copeia 2010(2):254-267) described a second species of Contia, C. longicaudae, from northern California and Oregon. There might be some hope here for the Pembroke, BC environmentalists if they can show their local sharp-tailed snake is a distinct - undescribed, cryptic species. But the fact of the matter is short-tailed snakes are not rare, just secretive. They give the impression of being rare because they are spending much of their time below ground. And, therefore are not good candidates for halting development.
Thursday, July 25, 2013
The northern Mexican gartersnake had a limited historical distribution in New Mexico that consisted of scattered locations throughout the Upper Gila River watershed in Grant and western Hidalgo Counties, including the Upper Gila River, Mule Creek in the San Francisco River sub-basin, and the Mimbres River. The species was detected at only 2 of 11 historical localities along the northern-most part of its range from which the subspecies was previously known. The only viable northern Mexican gartersnake populations in the United States where the subspecies remains reliably detected are all located in Arizona. In New Mexico, the northern Mexican gartersnake may occur in extremely low population densities within its historical distribution; limited survey effort is inconclusive to determine extirpation. The status of the northern Mexican gartersnake on tribal lands, such as those owned by the White Mountain or San Carlos Apache Tribes, is poorly known due to historically limited survey access and less is known about the current distribution of the northern Mexican gartersnake in Mexico due to limited access to information on survey efforts and field data from Mexico.
After no confirmed sightings in nearly twenty years, scientists discovered three northern Mexican gartersnakes along a stretch of the Gila River in southwestern New Mexico in June. After nearly three years of intensive searching, scientists with the BioPark Zoo in Albuquerque discovered three young males along the Gila, suggesting at least one viable reproducing population of the northern Mexican gartersnake exists in the region. Northern Mexican gartersnakes inhabit riparian wetland and prey on tadpoles and small fishes. More than 90% of their habitat has disappeared due to overgrazing, water diversions, wildfires and drought.
A proposed diversion of the Gila would alter the river’s modest flood pattern and transport water to an off-channel reservoir via a pipeline. This would damage some of the last remaining habitat in the Gila drainage.
The historical distribution of the narrow-headed gartersnake ranged across the Mogollon Rim and along its associated perennial drainages from central and eastern Arizona, southeast to southwestern New Mexico at elevations ranging from 2,300 to 8,000 ft (700 to 2,430 m). The species was historically distributed in headwater streams of the Gila River sub-basin that drain the Mogollon Rim and White Mountains in Arizona, and the Gila Wilderness in New Mexico; major sub-basins in its historical distribution included the Salt and Verde River sub-basins in Arizona, and the San Francisco and Gila River sub-basins in New Mexico Researchers suspect the species was likely not historically present in the lowest reaches of the Salt, Verde, and Gila rivers, even where perennial flow persists. Numerous records for the narrow-headed gartersnake (through 1996) in Arizona are maintained in the GFD’s Heritage Database. The narrow-headed gartersnake as currently recognized does not occur in Mexico. Recently narrow-headed gartersnakes were detected in only 5 of 16 historical localities in Arizona and New Mexico surveyed in 2004 and 2005. Population densities have noticeably declined in many populations, as compared to previous survey efforts.
The narrow-headed gartersnake populations have likely deteriorated as a result of declines in resident fish communities due to heavy ash from wild fires and sediment flows, but subsequent survey data have not been collected. If the Whitewater Creek and Middle Fork Gila River populations did decline as a result of these factors, only three remaining populations of this species remain viable today across their entire distribution. Unnaturally large wildfires have become increasingly common across the Mogollon Rim of Arizona and New Mexico where the narrow-headed gartersnake historically occurred.
Friday, July 19, 2013
Howdy Herpers, 07/20/13
First off, Typing Boy sometimes sends out "knock your socks off" missives that he expects multiple "ooos and ahhhs" from the gallery. And all he gets in return is the sound of crickets. There is no accounting for taste with this audience. Then, whilst mired in email Armageddon, he sends out a missive that requests responses from three people, and about 50 of you respond!
What with being a very active president of a herp society, organizing 2 new websites, and herping until he drops, I hope that those of you 50 who said "got it" will forgive me if I didn't respond with "got yours too!"
And if you don't know what I'm talking about, you're likely blessed to be on the second list that was spared that type of lunacy.
Count your blessings!
I'm going to do something that I've never done before. I'm not comfortable doing this. We all get emailed monetary leg humps from this org or that org--and at least they are smart enough, (desperate enough?), to become non profits. While we of the Suizo Project SHOULD do that--the 800-1200 bucks that it takes to do that always winds up being spent on transmitters, PIT tags, receivers etc. In other words--useful stuff!
Ok, enough with the BS. I'm asking for money. A new batch of transmitters have just arrived. The little old winemaker coughed up the 700 bucks to pay for that. This with the blessing of his lovely wife Dianna. This was just a stop gap order. Every one of those transmitters has already been requested by our subjects. (They don't know that they requested it, but they did.) Once those surgeries are done, there will be more animals that need the old transmitters that we yank. That will be another $700. And with three steady trackers, we have never have we been more ready to add in new animals.
Those are 400 bucks each. We've already released 2 VERY good candidates for the study due to fiscal woes.
So no, you can't take it off your taxes. We will of course entertain giving animals a name you choose for a hefty donation--but does that really matter? If you donate, you know that the study will continue, and you will also know that you can count on good reports so that you can herp vicariously with us. And join us on the ground as well.
To show what unmitigated gall we have, we're asking you to do this the hard way. Cut a check, make it out to me, stick it in an envelope, and send it to me at:
950 N. Cherry Ave
Tucson, AZ 85719
Every penny donated goes for equipment. We don't get a salary, and we pay gas and beer money out of pocket. (Although you have the right to designate the money be spent on beer. Who are we to turn down free binges?)
If you want to avoid all this hassle, and want to give, we can arrange to have you pay the makers of transmitters with a credit card.
Thanks for your consideration. If it doesn't bring in any money, we'll continue to the best we can with what we have. Thanks.
Good old female tiger rattlesnake # 12, "Ellie." Her transmitter was due to expire 7 June of this year. They normally expire early. By mid-May, the edict "get Ellie" was burned in our brains. Only you can't easily get something that remains invisible in rocky rubble-- unless you want to strip mine certain pristine patches of ground. That we will not do--we will lose an animal first. (Not necessarily because of strict environmental codes of ethics, but more likely because of our lack of desire to swing pick axes and shovels).
In all of 2013, we did not ONCE see Ellie up. With the few glimpses that we had of her, she was buried deeper than a Texas tick. Even those visuals were rare--only one for me. And so 7 June came and went, and we started to intensify the hunt for her. I have 20 write ups of the same rock shelf that is packed with Neotoma debris to show for these writeups. The saving grace was that she was in with a tortoise--so at least I got to watch that during the process.
FINALLY, on 6 July, we got our first rain storm. Every snake we tracked was up--including the erstwhile Ellie. It was nothing short of a miracle that her transmitter was still working. We snagged her, and noted that she was WAY too pregnant to endure a surgery and release. So, Marty hung on to her. She dropped five kids and one stillborn baby on 10 July. All the images that follow come to us by way of Marty Feldner.
I thought I'd start with the first courtship event that we witnessed last year, and bring us on to the present. The images are labeled clear enough for you to see the action. Note how skinny CT12 is after her ordeal. Can you spare 90 cents, so we buy her a mouse? :-)
We are currently watching two more pregnant tigers where transmitter changes will NOT be a problem. We also have one black-tailed rattlesnake about to drop. We hope to share these exciting moments with you insitu.
For now, whether you donate or not, please enjoy these breathtaking images. And know that more will be on your screen soon.
Best to all of you, roger
Allobates amissibilis sp. nov.,
newly discovered micro-endemic frog.
© M. Hölting & R. Ernst/Senckenberg.
The related study was published in the scientific journal “Organisms, Diversity and Evolution”. The Lost World, a famous novel released by the renowned British author Sir Arthur Conan Doyle in 1912, is set in to what, even today, is still a virtually forgotten and neglected area of our planet, the Guiana Shield in the north of South America. The region accounts for more than 25 percent of the world’s tropical rain forests, and is one of the four remaining extensive pristine forested areas left in the world (Amazon, Congo, Papua New Guinea and Guiana Shield). In a study sponsored by the Stiftung Artenschutz [Species Conservation Foundation] and the Verband Deutscher Zoodirektoren [Association of German Zoo Directors], the Dresden team, led by biologists Dr. Raffael Ernst and Monique Hölting investigated whether conservation of amphibians and ecotourism can be reconciled in the forests of Guyana. The investigations are being carried out in close co-operation with the international notfor-profit organization Iwokrama international Centre for Rain Forest Conservation and Development. Their idea is to test the concept of a truly sustainable forest, where conservation, biodiversity safeguarding, environmental balance and economic use can be mutually reinforcing. Beside forms of sustainable forest management, ecotourism concepts are also being tested. This is also true of the project area, Turu Falls, at the foot of the Iwokrama Mountains in the so-called Iwokrama Forest of Central Guyana.
The original aim of the study was to investigate the populations of Hoogmoeds harlequin frog (Atelopus hoogmoedi), in order to find out whether these morphologically very variable frogs may be affected by the planned tourism activities. The results will lead in the medium term to a sustainable development plan for the area, with Atelopus receiving the role here of a so-called flagship species, i.e. a species which stands as representative for the protection of the entire area. A frog that is virtually already lost. During the fieldwork for this project, the researchers were struck by an inconspicuous brown frog, only the size of a thumbnail, which they could not assign to any known species. As it turned out, it was indeed a hitherto undescribed species of poison dart frog which is now being scientifically described jointly by Dresden and Belgian scientists.
As inconspicuous as the frogs appear, they are unique. To date, only three species of the genus Allobates are known from Guyana, one of which, the Cuckoo frog, Allobates spumaponens Kok & Ernst 2007, was described for the first time by the same team in 2007. Moreover, the newly discovered little frog is the third known microendemic species, i.e. which only occurs in the very small area of the Iwokrama Mountains.
So far, only a gecko and a caecilian, a legless amphibian, are known from this area as having a similarly limited distribution. Because of their limited distribution and usually small total population sizes, micro-endemic species are particularly vulnerable to changes in their environment. It is therefore questionable whether the use of the area as a destination for ecotourism will not ultimately lead to the loss of a species, which has only just been discovered and thus has been made accessible to scientific investigation. In order to draw attention to this fact, researchers have given the little amphibian the distinctive name Allobates amissibilis (in Latin “that may be lost”).
We must nevertheless still hope that not least due to the research work of the Dresden team, all is not lost for the forgotten world in the north of South America.The Guiana Shield: Worthy of protection. Not least because of the high number of endemic species, the region is one of the most important centers of biodiversity in the tropics of the New World. Even though the forests of the Guiana Shield have had among the lowest deforestation rates of the world, with very little change over the past decades, rapid economic and social changes are posing increasing pressures on these relatively well conserved forest ecosystems. The Guianas are at a crossroads concerning decisions and trade-offs among utilization, conservation and preservation of their forests and thus substantial parts of the region’s biodiversity
Kok PJR, Hölting M, Ernst R. 2013. A third microendemic to the Iwokrama Mountains of central Guyana: a new “cryptic” species of Allobates Zimmerman and Zimmerman, 1988 (Anura: Aromobatidae). Organisms Diversity & Evolution, 2013; DOI: 10.1007/s13127-013-0144-4
Wednesday, July 17, 2013
The authors ask the questions: (1) Do crocodilians consume fruit and if so, how widespread is this behavior among the order Crocodylia? (2) If fruits are present in the diet, are these ingested incidental to prey capture, consumed as gastroliths, derived secondarily from ingested prey or deliberately ingested as food? (3) Does fruit consumption yield a nutritional reward for crocodilians? (4) What is the fate of fruits and seeds ingested by crocodilians? (5) Are movement patterns of crocodiles likely to extend the seed shadow much beyond the parent plant? (6) What are the ecological implications of this plant–animal interaction; that is, do crocodilians function as seed dispersers?
The authors find frugivory is widespread among the Crocodylia and while some frugivory is certainly accidental, but the literature leaves little doubt that on occasion, crocodilians deliberately eat fruit. Crocodilians are probably best considered occasional frugivores that is, generalist predators that complement an otherwise carnivorous diet with fruit, which is consumed infrequently and usually, but not always in small quantities.
Although fruit seems of limited importance in crocodilian diets, nutritional beneﬁts are likely. The diversity of fruit types consumed by crocodilians seems to preclude the existence of a speciﬁc crocodilian dispersal syndrome similar to that described for other reptiles (aromatic, colorful fruits, borne at ground level or dropped at maturity) . Nonetheless, several lines of evidence strongly suggest that crocodilians potentially function as effective agents of seed dispersal. They are capable of ingesting large numbers of fruits and seeds, and because these are swallowed without mastication, seeds are likely to escape damage during ingestion. Also, the large gape capacity of crocodilians permits the ingestion of large fruits. Once ingested, the fate of seeds is less clear; while digestive predation of some seeds undoubtedly occurs, most are probably regurgitated or excreted in the feces. Because crocodilians have large territories and frequently undertake lengthy movements, they are capable of generating extensive seed shadows; seeds are transported well beyond the parent plant before being voided. Although little is known about the ultimate deposition of seeds ingested by crocodilians, the few available reports suggest that defecation sites could prove suitable for seed germination. The authors conclude that it likely that crocodilians function as signiﬁcant seed dispersal agents in many freshwater ecosystems.
Platt, S. G., Elsey, R. M., Liu, H., Rainwater, T. R., Nifong, J. C., Rosenblatt, A. E., Heithaus, M. R. and Mazzotti, F. J. (2013), Frugivory and seed dispersal by crocodilians: an overlooked form of saurochory?. Journal of Zoology. doi: 10.1111/jzo.12052
Saturday, July 13, 2013
Alan et al built a molecular phylogeny using up to 4 genes for each taxon: 2 mitochondrial (cytochrome b and ND4) and 2 nuclear (c-mos and RAG1). They used 171 taxa from Australia and North America. They then collected colored photographs of each species of snake, excluding captive bread specimens - using 828 photos in all. The third step was to gather ecological information on each species using the literature. They then used an R-D model, and recruited observers to classify the patterns. They then used a phylogenetic generalized least squares (PGLS) analyses in the caper package for R (R Development Core Team) to determine how snake patterns are related to ecology and behavior.
They found a uniform pattern was associated with an active hunting strategy. Species with longitudinal stripes were generally small, fast, and often exposed to visually hunting predators. Species frequently classified as having regular spotted patterns were more common in North America, found frequently near cover, and predators of birds. Transverse stripes were seldom on species with grasslands or arboreal lifestyle. When they removed coral snake mimics from the sample, transverse stripes are predicted by erratic movement, habitat specialism, and egg consumption. Blotched patterns associated with an ambush hunting strategy, slow movement, large body size, and pungent cloacal defense. The model of complex patterning showed a positive association toward species where females grow longer than males, those which live in North America and those which are more terrestrial.
High contrast between the colors and tones of pattern elements was observed on small terrestrial snakes and those that can move rapidly away from threats. Habitat generalists generally had patterns with smaller elements in absolute terms, but none of the predictors were associated with the size of pattern elements relative to snout-vent length.
When mimics were included in the analysis, no predictors were related to the cryptic color score. However, when mimics were removed, the minimal adequate color model included main effects of escape speed, mammalian predation, and cloacal defense, with snakes that are slow, predate on mammals, and described as having highly pungent cloacal defenses generally having more cryptic colors.
Transverse striped snakes did not show a clear overall pattern to eco-behavioral associations; the idea that transverse stripes achieve flicker-fusion during escape is plausible but requires focused empirical testing. Though analysis of snake color was coarse, the expectation that bright colors would be common on well-defended species to function as an aposematic signal was not supported; the factors that lead to the evolution of warning coloration in snakes await further investigation.
Allen WL, Baddeley R, Scott-Samuel NE, Cuthill IC. 2013, The evolution and function of pattern diversity in snakes. Behavioral Ecology 10.1093/beheco/art058
Friday, July 12, 2013
|The asp viper. Photo credit: Felix Reimann|
Rugieroa and colleagues (2013) have recently published an analysis of the changes in phenology which have occurred in the last 20 years in a marked population of the asp viper. And, they relate these changes to the intervening climatic changes. They examined three metrics of the viper's annual phenology: (1) annual onset of above-ground activity; (2) annual onset of feeding period; (3) annual onset of the hibernation. The annual variations of these three phenological metrics were correlated to five climatic variables: (1) mean annual air temperature, (2) mean February air temperature, (3) mean July air temperature, (4) yearly number of rainy days, and (5) yearly number of days with rainstorm.
The 20-year study revealed that the asp vipers have shifted at least three traits of their annual phenology in a way consistent with predictions of the theoretical responses for a reptile species to a warming climate. The asp viper increased both onset of annual activity and onset of the feeding, whereas they delayed their entering into hibernation. They also demonstrated that these shifts were signiﬁcantly correlated to yearly annual air temperature, and that the percent of ﬁeld days between 20th February and 20th March without observed vipers decreased over the years. However, they found no signiﬁcant pattern when analyzing the correlation between rainfall and phenological traits. Thus, their results suggest that changing temperature and not rainfall is driving viper phenology.
Rugieroa L, Milanab G, Petrozzic F, Capulad M, Luiselli L. 2013. Climate-change-related shifts in annual phenology of a temperate snake during the last 20 years. Acta Oecologica 51:43-48
Thursday, July 11, 2013
Scientists analyzed how quickly species adapted to different climates in the past, using data from 540 living species from all major groups of terrestrial vertebrates, including amphibians, reptiles, birds and mammals. They then compared their rates of evolution to rates of climate change projected for the end of this century. This is the first study to compare past rates of adaption to future rates of climate change.
The results, published online in the journal Ecology Letters, show that terrestrial vertebrate species appear to evolve too slowly to be able to adapt to the dramatically warmer climate expected by 2100. The researchers suggested that many species may face extinction if they are unable to move or acclimate.
"Every species has a climatic niche which is the set of temperature and precipitation conditions in the area where it lives and where it can survive," explained John J. Wiens, a professor in UA's department of ecology and evolutionary biology in the College of Science. "For example, some species are found only in tropical areas, some only in cooler temperate areas, some live high in the mountains, and some live in the deserts."
Wiens conducted the research together with Ignacio Quintero, a postgraduate research assistant at Yale University.
"We found that on average, species usually adapt to different climatic conditions at a rate of only by about 1 degree Celsius per million years," Wiens explained. "But if global temperatures are going to rise by about 4 degrees over the next hundred years as predicted by the Intergovernmental Panel of Climate Change, that is where you get a huge difference in rates. What that suggests overall is that simply evolving to match these conditions may not be an option for many species."
For their analysis, Quintero and Wiens studied phylogenies – essentially evolutionary family trees showing how species are related to each other – based on genetic data. These trees reveal how long ago species split from each other. The sampling covered 17 families representing the major living groups of terrestrial vertebrates, including frogs, salamanders, lizards, snakes, crocodilians, birds and mammals.
They then combined these evolutionary trees with data on the climatic niche of each species to estimate how quickly climatic niches evolve among species, using climatic data such as annual mean temperature and annual precipitation as well as high and low extremes.
"Basically, we figured out how much species changed in their climatic niche on a given branch, and if we know how old a species is, we can estimate how quickly the climatic niche changes over time," Wiens explained. "For most sister species, we found that they evolved to live in habitats with an average temperature difference of only about 1 or 2 degrees Celsius over the course of one to a few million years."
"We then compared the rates of change over time in the past to projections for what climatic conditions are going to be like in 2100 and looked at how different these rates are. If the rates were similar, it would suggest there is a potential for species to evolve quickly enough to be able to survive, but in most cases, we found those rates to be different by about 10,000-fold or more," he said.
"According to our data, almost all groups have at least some species that are potentially endangered, particularly tropical species."
Species can respond to climate change by acclimating without evolutionary change or by moving over space to track their preferred climate. For example, some species might be able to move to higher latitudes or higher elevation to remain in suitable conditions as the climate warms. In addition, many species could lose many populations due to climate change but might still be able to persist as a species if some of their populations survive. Barring any these options, extinction is the most likely outcome.
He explained that moving to more suitable climatic conditions may not always be an option for many species.
"Some studies suggest many species won't be able to move fast enough," he said. "Also, moving may require unimpeded access to habitats that have not been heavily disturbed by humans. Or consider a species living on the top of a mountain. If it gets too warm or dry up there, they can't go anywhere."
In an earlier study, Wiens and co-authors asked what might actually cause species to go extinct. They showed that species extinctions and declines from climate change are more often due to changes in interactions with other species rather than inability to cope with changing conditions physiologically.
"What seemed to be a big driver in many species declines was reduced food availability," Wiens said. "For example, bighorn sheep: If it gets drier and drier, the grass gets sparse and they starve to death."
Quintero I, Wiens JJ, 2013. ates of projected climate change dramatically exceed past rates of climatic niche evolution among vertebrate species. Ecological Letters DOI: 10.1111/ele.12144.
By observing the development of different animal species and confirming their results with fossil analysis and genomic data, researchers from the RIKEN Center for Developmental Biology show that the shell on the turtle's back derives only from its ancestors' ribcage and not from a combination of internal and external bone structures as is often thought. Their study is published today in the journal Nature Communications.
The skeleton of vertebrates has evolved throughout history from two different structures, called the endo- and exoskeleton. In the human skeleton, the backbone and bones of the limbs evolved from the endoskeleton, whereas most of the skull elements derive from the exoskeleton. Fish scales and the alligator's bony skin nodules are other examples of exoskeletons.
The origin of the shell on the turtle's back, or carapace, was unclear until now because it comprises parts of obvious endoskeletal origin and others that look more like the exoskeleton of alligators and fish. The outer part of the turtle carapace was thought to have derived from exoskeletal bones, while the internal part has been shown to originate from ribs and vertebrae and to be connected to the internal skeleton of the animal. However, no direct evidence has been obtained to show that the bony structures developing outside the ribcage in turtles derived from the exoskeleton.
To investigate whether the turtle carapace evolved with any contribution from its ancestors' exoskeleton, Dr. Tatsuya Hirasawa and his team carefully observed developing embryos of Chinese soft-shell turtles, chickens and alligators.
In their analysis, they compared the development of the turtle carapace, the chick's ribs and the alligator's bony skin nodules.
The researchers found that the major part of the turtle's carapace is made from hypertrophied ribs and vertebrae and therefore derives solely from endoskeletal tissue.
This finding was confirmed by the observation of fossils of the ancient turtle Odontochelys and the ancient reptile Sinosaurosphargis, that both exhibit shells of endoskeletal origin. Odontochelys has a rigid shell instead of a flexible ribcage. And Sinosaurosphargis possesses an endoskeletal shell similar to the turtle's under, and separate from, a layer of exoskeletal bones.
Taken together these results show that the turtle carapace has evolved independently from the exoskeleton. This scenario is also consistent with the recent phylogenetic analyses based on genomic data that have placed turtles in the same group as birds, crocodiles and marine reptiles like Sinosaurophargis, contradicting recent studies based solely on fossil record.
"Recently, genomic analyses had given us evidence that turtles evolved from reptiles closely related to alligators and dinosaurs, not from primitive reptiles as once thought. Our findings match the evolutionary history revealed by the genomic analyses, and we are about to unravel the mystery of when and how the turtle shell evolved," explains Dr. Tatsuya Hirasawa who led the research.
"Our aim is to one day understand it as well as we understand the evolution of birds from dinosaurs," he concludes.
Tatsuya Hirasawa, Hiroshi Nagashima, Shigeru Kuratani. The endoskeletal origin of the turtle carapace. Nature Communications, 2013; 4 DOI: 10.1038/ncomms3107
Monday, July 8, 2013
|The holotype of Azemiops kharini (ZISP 26028) from Tam Dao, Vinh Phuc Province, Vietnam.|
For many decades Azemiops fea was known from relatively few specimens, all had been collected in mountainous regions at altitudes up to 1000 m, with cool climates and they could be found in disturbed areas, including agricultural areas and secondary forests in southern China and north Vietnam. The monotypic species was known to feed on small mammals, with the only known specific prey - the common gray shrew (Crocidura attenuata).
Now, Orlov et al. (2013) have described Azemiops kharini, a second species of primitive viper from Tam Dao Mountain, Tam Dao Village, Vinh Phuc Province, Vietnam The new species, known as the white-head Burmese viper has a broader distribution than the blackhead Fea's viper. The new species ranges from eastern China (eastern Yunnan, Guangxi, Guizhou, eastern Sichuan, Fujian, Zhejiang, Jiangxi, and Shaanxi provinces) and it is present in northern Indochina (northeastern Vietnam) The limited number of specimens probably under represents the distribution, but the two species of Azemiops are foundb a short distance from each other, and are apparently separated by the Red River Valley. Azemiops feae occurs west of the Red River, and Azemiops kharini occurs to the east of the Red River.
The white-head Burmese viper inhabits bamboo and tree-ferns thickets interchanged with open and lighted zones with deep leaf litter. Typical habitat is leaf litter near the trunks of fallen trees, with ferns and crevices in limestone rocks. Food is mostly rodents that are associated with swift, montane streams. It is active from the middle of May and lays clutches of five eggs.
Orlov NL, Ryabovn SA, Nguyen TT. 2013. On the Taxonomy and the Distribution of Snakes of the Genus Azemiops Boulenger, 1888: Description of a New Species. Russian Journal of Herpetology 20:110-128.
Wednesday, July 3, 2013
Gibbs et al (2013) characterized the variation in venom for all members of the Sistrurus clade with a “venomic” analysis of pooled venoms from two members of this genus, S. milarius streckeri and S. m. milarius. These venoms exhibit the same general classes of proteins as those found in other Sistrurus species but differ in their relative abundances of specific protein families. The authors tested for significant phylogenetic signal in the relative abundances of major venom proteins across species and if diet (measured as percent mammals and lizards among all prey consumed) covaries with venom composition after phylogenetic divergence is accounted for. They found no evidence for significant phylogenetic signal in venom variation: K values for seven snake venom proteins and two composite venom variables [PC 1 and 2] were all nonsignificant and lower (mean = 0.11+0.06 sd) than mean K values (>0.35) previously reported for a wide range of morphological, life history, physiological and behavioral traits from other species. Finally, analyses based on Phylogenetic Generalized Least Squares (PGLS) methods reveal that variation in abundance of some venom proteins, most strongly CRISP is significantly related to snake diet. Their results demonstrate that venom variation in these snakes is evolutionarily a highly labile trait even among very closely-related taxa and that natural selection acting through diet variation may play a role in molding the relative abundance of specific venom proteins.
Gibbs HL, Sanz L, Sovic MG, Calvete JJ (2013) Phylogeny-Based Comparative Analysis of Venom Proteome Variation in a Clade of Rattlesnakes (Sistrurus sp.). PLoS ONE 8(6): e67220. doi:10.1371/journal.pone.0067220