Thursday, May 25, 2017

Cuban boas coordinate their hunting behavior

Snakes have long been thought to be solitary hunters. A new study from the University of Tennessee, Knoxville, shows that the Cuban boa (Chilabothrus angulifer) coordinate their hunts to increase their chances of success. Vladimir Dinets, a research assistant professor of psychology at the University of Tennessee, observed Cuban Boa's hunting behavior in bat caves. Many Cuban caves shelter large bat colonies, and in some of them small populations of boas regularly hunt bats as they fly out at dusk and return at dawn. Dinets noticed that the boas hung down from the ceiling of the cave entrance and grabbed passing bats in midair. He found that if more than one boa was present, the snakes coordinated their positions in such a way that they formed a wall across the entrance. This made it difficult or impossible for the bats to pass without getting within striking distance of at least one boa. Such group hunts were always successful, and the more snakes present the less time it took each to capture a bat. But if there was only one boa, it sometimes failed to secure a meal. These findings were recently published open-access in the journal Animal Behavior and Cognition. To date, only a handful of snakes have been observed hunting in groups, and coordination among them -- or among any other group-hunting reptiles -- has never been proven, Dinets said. Only a few of the world's 3,650 snake species have ever been observed hunting in the wild, so very little is known about snakes' diverse hunting tactics. "It is possible that coordinated hunting is not uncommon among snakes, but it will take a lot of very patient field research to find out," Dinets said. He added that observing the Cuban boa, although an amazing spectacle, is becoming increasingly difficult since only the most remote caves still have boas. The boas are being hunted for food and possibly pet trade. "I suspect that if their numbers in a cave fall, they can't hunt in groups anymore and might die out even if some of them don't get caught by hunters," Dinets said. "A few of these caves are in national parks, but there's a lot of poaching everywhere."




Citation

 Dinets V. 2017. Coordinated hunting by Cuban boas. Animal Behavior and Cognition, May 2017 DOI: 10.12966/abc.02.02.2017

Coral snake mimic loses pattern in absences of coral snake model

Tobago's Erythrolamprus ocellatus above. Trinidad's coral snake 
mimic E.  
aesculapii below.
Losses of adaptations in response to changed selective pressures are evolutionarily important phenomena but relatively few empirical examples have been investigated in detail. To help fill this gap, Hodson and Lehtinen took advantage of a natural experiment in which coral snake mimics occur on two nearby tropical islands, one that has coral snake models (Trinidad) and one that lacks them (Tobago).

The Tobago snake's pattern represents a loss of an adaptation in response to changed selective pressures. Relatively few empirical examples of adaptation loss have been investigated in detail. Hodson and Lehtinen took advantage of a natural experiment in which coral snake mimics occur on two nearby tropical islands, one that has coral snake models (Trinidad) and one that lacks them (Tobago). On Tobago, an endemic coral snake mimic (Erythrolamprus ocellatus) exists but has a relatively poor resemblance to coral snakes. Quantitative image analysis of museum specimens confirmed that E. ocellatus is a poor mimic of coral snakes.

To address questions related to the functional importance of this phenotype, the authors conducted a field experiment on both islands with snake replicas made of clay. These results clearly indicated a strong inter-island difference in predator attack rates where snake replicas that resembled coral snakes received protection in Trinidad but not in Tobago. Color patterns from museum specimens confirmed that E. ocellatus is indeed a poor mimic of coral snakes in many respects, especially in regards to the relative proportions of colors and the lack of discrete band. This implies that the classic coral snake mimicry adaptation has been degraded in this species. Field experiment revealed that E. ocellatus replicas were not protected from predator attacks on Tobago (where no coral snakes occur) compared to controls. However, on Trinidad (where coral snakes do occur) we found the expected lower attack rate on coral snake and mimic replicas compared to controls. Thus, E. ocellatus does not just look like a poor mimic to human eyes, its predators show no evidence of avoiding it.

Further, a molecular phylogenetic analysis of the ancestry of E. ocellatus revealed that this poor coral snake mimic is deeply nested in a clade of good coral snake mimics. Therefore the lack of coral snakes on Tobago altered the selective environment such that the coral snake mimicry adaptation was no longer advantageous. The failure to maintain this ancestral feature in allopatry provides a compelling example of how losses of complex adaptations can occur.

Citation
Hodson EE, Lehtinen RM. 2017. Diverse Evidence for the Decline of an Adaptation in a Coral Snake Mimic. Evolutionary Biology. 2017:1-0.

Monday, May 22, 2017

The last European varanid

The Desert Monitor, Varanus griseus is the extant species
with the closest distribution to Europe today
In a recent paper, Georgalis et al. (2017) report the remains of a varanid lizard from the middle Pleistocene of the Tourkobounia 5 locality near Athens, Greece. The new fossil material comprises cranial elements only (one maxilla, one dentary, and one tooth) and is attributed to the monitor lizard genus Varanus, the genus to which all European Neogene varanid remains have been assigned. Previously, the most recent undisputed varanid from Europe had been recovered from upper Pliocene sediments. The new Greek fossils, therefore, constitute the most recent records of monitor lizards from the continent. Despite being incomplete, this new material enhances our understanding of the cranial anatomy of the last European monitor lizards and is clearly not referable to any of the extant species such as Varanus griseus or Varanus niloticus - the only species that could be taken into consideration on a present-day geographic basis. However, these fossils could represent a survivor of the monitor lizards of Asian origin that inhabited Europe during the Neogene. Varanids first appear in the European fossil record during the Eocene. They are entirely absent from the European Oligocene faunas but appear again in the fossil record after the early Miocene. It is possible the European Paleogene varanids were victims of the Grande Coupure. The Grande Coupure refers to a break or change in faunal continuity about 33.5 MYA and marks the the end of the Eocene assemblages of mammals, with the arrival of Asian species in Europe. The authors note that on the basis of the available data this cannot be demonstrated with certainty. All of the Neogene European varanids appear to be members of Varanus, and they seem to have dispersed into Europe in the early Miocene. In fact, the earliest evidence of the genus on the European continent is recorded in the early Miocene of Spain. Whether these early Miocene immigrants originated directly from Africa or have Asian affinities cannot be demonstrated with certainty. The occurrence of Varanus-like forms in the late Eocene and early Oligocene of Egypt favors an African origin, but the Asian record is too weak to offer any insights. The fact that the maxilla from Tourkobounia 5 does not show any relationship with extant African taxa (V. albigularis, V. exanthematicus, V. griseus, V. niloticus, V. ornatus) suggests Asian affinities, as already reported for the extinct Varanus amnhophilis from the late Miocene of Samos. Whatever their exact origin, monitor lizards rapidly achieved a wide distribution throughout Europe during the Miocene. Fossils attributed to this genus have been described from localities in Austria, Germany, Greece, Hungary, Italy, Moldova, Portugal, Romania, Spain, and the Ukraine.

Citation

Georgalis, G. L., A. Villa, and M. Delfino. 2017. The last European varanid: demise and extinction of monitor lizards (Squamata, Varanidae) from Europe. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1301946.

Sunday, May 21, 2017

Some monitor lizards have not recovered from the introduction of the cane toad

Varanus panoptes Image credit: Greg Hume

The impact of invasive species is often underestimated by many. However, invasives can trigger trophic cascades in animal communities but published cases documenting the results of removing top predators are extremely rare. An exception is the invasive cane toad (Rhinella marina) in Australia, which has caused severe population declines in monitor lizards, triggering trophic cascades that facilitated dramatic and sometimes unexpected increases in several prey of the predators, including smaller lizards, snakes, turtles, crocodiles, and birds. Persistence of isolated populations of predators with a decades-long co-existence with toads suggests the possibility of recovery, but alternative explanations are possible. In a new paper, Doody et al. (2017)  note that confirming predator recovery requires longer-term study of populations with both baseline and immediate post-invasion densities. The authors had previously quantified the short-term impacts of the invasive cane toads over seven years at two sites in tropical Australia. In the new paper, they test the hypothesis that predators have begun to recover by repeating the study 12 years after the initial toad invasion. The three predatory lizards (Varanus panoptes, V. mertensi, V. mitchelli) that experienced 71-97% declines in the short-term study showed no sign of recovery, and indeed a worse fate. Two of the three species  (Varanus panoptes and V. mitchelli) were no longer detectable in 630 km of river surveys, suggesting local extirpation. Two mesopredators that had increased markedly in the short-term due to the above predator losses showed diverse responses in the medium-term; a small lizard species increased by about 500%, while populations of a snake species showed little change. Their results indicate a system still in ecological turmoil, having not yet reached a ‘new equilibrium’ more than a decade after the initial invasion; predator losses due to this toxic invasive species, and thus downstream effects, were not transient. Given that cane toads have proven too prolific to eradicate or control, we suggest that recovery of impacted predators must occur unassisted by evolutionary means: dispersal into extinction sites from surviving populations with alleles for toxin resistance or toad avoidance. Evolution and subsequent dispersal may be the only solution for a number of species or communities affected by invasive species for which control is either prohibitively expensive, or not possible.

Citation
Doody JS, Rhind D, Green B, Castellano C, McHenry C, Clulow S. 2017. Chronic effects of an invasive species on an animal community. Ecology. 2017 May 6.



Norisophis begaa, a new basal snake from the early Cretaceous

Image credits: Tyler Keillor (sculpture) and Ximena Erickson
(original photography); modified by Bonnie Miljour. 
Klein et al. (2017) note that fossil snakes are well represented in the Upper Cretaceous of northern Africa (99.7 to 94.3 MYA), with material known from Morocco, Sudan, Egypt, Libya, Algeria, and Niger. The Moroccan Kem Kem beds have yielded a particularly diverse snake assemblage, with members of the families Simoliophiidae, Madtsoiidae, ?Nigerophiidae and several unnamed taxa co-occurring. These fossils are important for our understanding of the early evolutionary history of snakes, and may shed light on the ecology and initial diversification of basal snakes. Klien and colleagues (2017) describe a new taxon, Norisophis begaa, from the Kem Kem beds of Begaa, at  at Aferdou N'Chaft, in southeast Morocco. Although known only from vertebrae, the unique appearance of the fossils adds to our knowledge regarding the early history the snake fauna of the northern Africa's Late Cretaceous. The vertebrae are characterised by a marked interzygapophyseal constriction, parazygantral foramina, an incipient prezygapophyseal process, and an anterio-posteriorly short centrum. Several characteristics shared with Najash, Seismophis, Madtsoiidae, and Coniophis suggest that Norisophis is a stem ophidian. N. begaa further increases the diversity and disparity of snakes within the Kem Kem beds, supporting the hypothesis that Africa was a mid-Cretaceous hotspot for snake diversity.

Citation
Klein CG, Longrich NR, Ibrahim N, Zouhri S, Martill DM. 2017. A new basal snake from the mid-Cretaceous of Morocco. Cretaceous Research. 2017 Apr 30;72:134-41.

The rediscover of some Brazilian anoles and their biogeographic significance

Brazil's Atlantic Forest has montane ranges with an exceptionally high diversity of endemic amphibians and reptiles. Connections between this area and other areas of South America have been proposed as reason. In a new paper Ivan Prates and colleagues report the the rediscovery of Anolis nasofrontalis and Anolis pseudotigrinus, two mainland species from the Brazilian Atlantic Forest that were not reported for more than 40 years.

Coloration in life of Anolis nasofrontalis (A, B) and A. pseudotigrinus (C, D). In A, inset shows the black 
throat lining of A. nasofrontalis. Photographed specimens are females. Ivan Prates

By combine new genetic data with published sequences of species in the Dactyloa clade of Anolis they were able to investigate the phylogenetic relationships of A. nasofrontalis and A. pseudotigrinus, as well as estimate divergence times from their closest relatives.  The phylogenetic analysis recovered six main clades within Dactyloa, five of which were previously referred to as species series (aequatorialis, heterodermus, latifrons, punctatus, roquet). A sixth clade clustered A. nasofrontalis and A. pseudotigrinus with A. dissimilis from western Amazonia, A. calimae from the Andes, A. neblininus from the Guiana Shield, and two undescribed Andean taxa. This allowed them to  define a sixth species series within Dactyloa: the neblininus series. Close phylogenetic relationships between highly disjunct, narrowly-distributed anoles suggest that patches of suitable habitat connected the southern Atlantic Forest to western South America during the Miocene, in agreement with the age of former connections between the central Andes and the Brazilian Shield as a result of Andean orogeny. The data also support the view of recurrent evolution (or loss) of a twig anole-like phenotype in mainland anoles association with montane regions.

The neblininus series is composed of narrowly-distributed species that occur in mid-elevation sites, or adjacent habitats in the case of A. dissimilis, separated by large geographic distances. This pattern suggests a complex biogeographic history involving former patches of suitable habitat between regions, followed by habitat retraction and extinction in the intervening areas. In the case of A. nasofrontalis and A. pseudotigrinus, for instance, past forest corridors may explain a close relationship with the western Amazonian A. dissimilis. Atlantic and Amazonian rainforests are presently separated by open savannas and shrublands, yet geochemical records suggest that former pulses of increased precipitation and wet forest expansion have favored intermittent connections between them. These connections may have also been favored by major landscape shifts as a result of Andean orogeny, such as the establishment of the Chapare buttress, a land bridge that connected the central Andes to the western edge of the Brazilian Shield during the Miocene.

During morphological examinations of A. nasofrontalis and A. pseudotigrinus, it became apparent that these two species are not very different from Caribbean twig anoles, with whom they share short limbs and cryptic coloration. These features are also present in other, distantly-related mainland anoles, such as A. euskalerriari, A. orcesi, A. proboscis, and A. tigrinus. Phylogenetic relationships support that a twig anole-like phenotype was acquired (or lost) independently within Dactyloa, perhaps as a result of adaptive convergence. Alternatively, this pattern may reflect the conservation of an ancestral phenotype. In the former case, an apparent association with South American mountains is intriguing.

Unfortunately, natural history data from A. nasofrontalis and A. pseudotigrinus are lacking. It is currently unclear whether they  exhibit the typical ecological and behavioral traits that characterize the Caribbean twig anole ecomorph, such as active foraging, slow movements, infrequent running or jumping, and preference for narrow perching surfaces.

Citations

Prates I, Melo-Sampaio PR, de Oliveira Drummond L, Teixeira M, Rodrigues MT, Carnaval AC. 2017. Biogeographic links between southern Atlantic Forest and western South America: rediscovery, re-description, and phylogenetic relationships of two rare montane anole lizards from Brazil. Molecular Phylogenetics and Evolution. 2017 May 11.

Prates, I. 2017. Legendary Brazilian Anoles Rediscovered. http://www.anoleannals.org/2017/05/14/legendary-brazilian-anoles-rediscovered/


Friday, May 19, 2017

First warm blooded vertebrate, Ophiacodon?

Ophiacodon mirus. Image Credit ru.wikapedia

People who like watching lizards often get the best opportunity to do so in the morning, as they can usually be found sunbathing at this time of day. This is because they rely on an external energy supply to reach their operating temperature. However, mice and other mammals make themselves nice and cozy in a different way: they burn calories and can even keep themselves warm during a bitterly cold winter's night.

Mammals are thus referred to as warm-blooded. Until now, it was thought that the "body heater" was invented in four-legged land animals around 270 million years ago. "However, our results indicate that warm-bloodedness could have been created 20 to 30 million years earlier," explains Prof. Martin Sander from the Steinmann Institute for Geology, Mineralogy and Paleontology at the University of Bonn.

For long-extinct animals, it is naturally not possible to simply determine body temperature using a thermometer. However, warm-bloodedness leaves behind tell-tale signs in fossils. It not only means that the animal is not reliant on the ambient temperature, but also enables faster growth. "And this is shown in the structure of the bones," explains Sander.

Bones are composites of protein fibers, collagen, and a biomaterial, hydroxyapatite. The more orderly the arrangement of the collagen fibers, the more stable the bone, but the more slowly it normally grows as well. The bones of mammals thus have a special structure. This allows them to grow quickly and yet remain stable. "We call this bone form fibrolamellar," says the paleontologist.

Together with his PhD student Christen D. Shelton (now at the University of Cape Town), the scientist looked at humerus bones and femurs from a long-extinct land animal: the mammal predecessor Ophiacodon. This lived 300 million years ago. "Even in Ophiacodon, the bones grew as fibrolamellar bones," says Sander to summarize the analysis results. "This indicates that the animal could already have been warm-blooded."

Ophiacodon was up to two meters long, but otherwise resembled today's lizards -- and not without good reason: mammals and reptiles are related; they thus share a predecessor. In the family tree, Ophiacodon is very close to the place where these two branches separate.

However, lizards, turtles and other reptiles living today are cold-blooded. Until now, it has been assumed that this was the original form of the metabolism -- i.e. that the shared ancestor of both animal groups was cold-blooded. Warm-bloodedness would thus be a further development, which arose over the course of mammalian evolution.

However, Ophiacodon appears a very short time after the division between mammals and reptiles. "This raises the question of whether its warm-bloodedness was actually a completely new development or whether even the very first land animals before the separation of both branches were warm-blooded," says Sander. That is just speculation. However, if this theory is correct, we would have to drastically correct our image: the first reptiles would then also have been warm-blooded -- and would have only discarded this type of metabolism later.



Citation
Shelton CD, Sander PM. 2017. Long bone histology of Ophiacodon reveals the geologically earliest occurrence of fibrolamellar bone in the mammalian stem lineage. Comptes Rendus Palevol, 2017; DOI: 10.1016/j.crpv.2017.02.00

Tuesday, April 11, 2017

Crack pots, insanity, and some really sick human beings

Snakes provide a variety of ecosystem services, not the least of which is rodent control. This is a free service provide by nature. However, like much of what is free, Republicans insist on privatizing it so somebody can make a profit.

Arizona HB2022 failed on a tie vote yesterday (April 10, 2017). The bill, if passed, would have allowed citizens to shoot "snake shot" within city limits in the State of Arizona. The Arizona Daily Star today (April 11) attributes the failure of the bill to a letter from Mike Cardwell an employee of the San Bernadino County Sherrif's office (California) and a herpetologist. Kudo's to Mike for sending the letter. The Cardwell letter included the following "The bottom line when it comes to destroying small animals like rattlesnakes is that that gun fire presents a much greater danger to by-standers than the snake itself."

Where is the Hantavirus when you need?  Oh, the snakes are controlling the rodents that carry it! The New Mexico Department of Health announced April 7th that a 54-year-old man from San Juan County has died of Hantavirus Pulmonary Syndrome (HPS). This is the second case of HPS confirmed in New Mexico this year. Snakes control rodents that carry this virus and reduce the probability that it will be transmitted to humans.

Just so you understand where this kind of proposed legislation comes from - here is the argument for the law, made by Chris Eger, at Guns.com. The comments that accompany this post are eye-opening.

A House measure advancing through committee would allow the use of specialty ammo inside Arizona cities for snakes and rats but is drawing fire from animal rights groups.
The bill, proposed earlier this month in the state House, has been winding its way through hearings and has gotten an initial nod from lawmakers, though its sponsor cautions it is not an animal regulation proposal.
“It’s a firearms bill,” said Rep. Jay Lawrence, R-Scottsdale. “It’s not a bill that deals with harming snakes or rats or any other vermin, it merely is a firearms bill.”
Lawrence’s measure, HB 2022, would amend state law to allow the use of rat or snake shot to control pests. The cartridges, instead of using a solid bullet, utilize a plastic cap or shell that holds a quantity of small diameter shot. The bill’s language only allows for .22 caliber shot rounds with pellets 1.3mm or less in diameter.
Currently, only the use of blanks is allowed within city limits to control pests.
Not all are impressed by the bill, especially reptile advocates who point out there are at least four species of endangered snakes at large in Arizona.
Russ Johnson of the Phoenix Herpetological Society told local media the proposal is fraught with pitfalls.
“Do we really want people shooting guns in the city limits next to houses?” said Johnson. “You’re talking about shooting rats. So you’re shooting on your rooftop, so you got bird shot spraying everywhere. OK, if you’re shooting a snake, you’re pointing down. You’re gonna get a ricochet even though it’s pellet.”
HB 2022 has passed both the JPS and Rules committees.
Filed Under: Ammunition, Politics & 2nd Amendment


Monday, April 10, 2017

Logging & Leatherbacks


Leatherback turtle hatchlings. Photo Credit: Juan Patiño
 Debris from logging in tropical forests is threatening the survival of hatchling leatherback turtles and the success of mothers at one of the world's most important nesting sites in Colombia.

New research by the University of Exeter and the Doñana Biological Station in Seville, Spain, has found that debris on beaches caused by logging activity is impacting both young turtles and their mothers during the key periods of their life cycles.

Leatherbacks are at particular risk of being caught up in fishing nets and longlines as bycatch, because they are migratory, travelling long distances worldwide.

Many breeding sites are already under pressure from tourism.

But now, research published in the journal Marine Ecology Progress Series has revealed that the logging is an additional, previously underestimated threat.

To nest and breed successfully, females must be able to cross the sandy beaches to dig their nest to successfully incubate their eggs.

In turn, hatchlings must be able to cross the sand unaccompanied to reach the water.

Researchers found that the beach debris hindered this movement.The team monitored 216 turtles, comparing their activity in areas with high amounts of debris to low amounts, in a globally significant nesting site in Colombia.
 
They also manipulated the amount of debris to see how it changed behavior.

They found that females which nested in areas with higher amounts of debris were spent more time building their nest and tended to do so closer to the shoreline.

This meant they were more vulnerable to flooding, which puts their eggs at risk.

Some females were even wounded in the process.

The debris also meant it took longer for hatchlings to reach the sea, increasing their chance of being eaten by predators and meaning they had to expend more energy, making them more vulnerable.

Professor Brendan Godley, director of the Centre for Ecology and Conservation at the University of Exeter's Penryn Campus in Cornwall, is a co-author on the research.

He said: "Leatherback turtles are already under immense pressure, from fisheries bycatch and are also one of the species prone to ingesting marine plastic litter.

"Our research clearly indicates that logging presents another threat.

"It is now paramount that beach clean-up operations are built into logging activities to prevent further damage to this species."

Dr Adolfo Marco Llorente, of the Doñana Biological Station, said: "Although logging debris does not affect rates of nesting, it has a significant impact on where and how nests are built, which negatively affects both mothers and hatchlings.

"This is on a scale that could lead over time to reduction of the overall population.

"Simple measures could make a real difference, such as repositioning organic waste areas, or salvaging the wood debris as an energy source.

"It's also essential that logging practices that reduce the impact on the marine environment are implemented."



 Patino-Martinez J, Godley BJ,  Quiñones L,  Marco A. 2017.  Impact of tropical forest logging on the reproductive success of leatherback turtles. Marine Ecology Progress Series, 569: 205 DOI: 10.3354/meps12064

Friday, April 7, 2017

Lowland amphibians are at higher risk from future climate warming.


A new study of Peruvian frogs living at a wide variety of elevations -- from the Amazon floodplain to high Andes peaks -- lends support to the idea that lowland amphibians are at higher risk from future climate warming.

That's because the lowland creatures already live near the maximum temperatures they can tolerate, while high-elevation amphibians might be more buffered from increased temperatures, according to a study by University of Michigan ecologist Rudolf von May and his colleagues published online April 6 in the journal Ecology and Evolution.

Previous studies have suggested that lowland reptiles and amphibians are especially vulnerable to climate warming. But in most cases, those conclusions were based on computer modeling work that incorporated a limited amount of field data.

"Understanding how species respond to climatic variation is critical for conserving species in future climatic conditions. Yet for most groups of organisms distributed in tropical areas, data about species' critical thermal limits are limited," said von May, a postdoctoral researcher in the U-M Department of Ecology and Evolutionary Biology.

"I think the contribution of our study is that it focuses on a group of closely related frog species distributed along a single montane gradient and that it includes empirical data on species' tolerance to heat and cold, as well as air temperatures measured along the same gradient."

In the process of conducting the study, which involved more than two years of fieldwork, von May and his colleagues identified three previously unknown frog species. Those newly discovered species will be described separately in a series of journal articles.

The elevational-gradient study focused on the thermal ecology and evolution of 22 species of land-breeding frogs, which are also known as terrestrial-breeding frogs, in southern Peru's Manu National Park and surrounding areas. Sampled elevations ranged from the Amazon River floodplain, at 820 feet above sea level, to 12,000-foot Andes Mountains peaks.

The region in and around Manu National Park is known for long-held records of biodiversity including more than 1,000 species of birds -- about 10 percent of the world's bird species -- and more than 1,200 species of butterflies. In addition, the park contains an estimated 2.2 percent of the world's amphibians and 1.5 percent of its reptiles.

While most frogs lay eggs in water, terrestrial-breeding frogs use a specialized reproductive mode called direct development: A clutch of embryos hatch directly into froglets; there are no free-living tadpoles. Terrestrial-breeding frogs form a diverse group that can exploit a wide variety of habitats, as long as those locations contain sufficient moisture.

In the study, the researchers looked at how closely related frog species differ in their elevational distribution and their tolerance to heat and cold in a region of the tropical Andes where temperature increase is predicted to be detrimental for most species.

"These measurements were taken in order to determine whether tropical frogs could take the heat -- or cold -- predicted for tropical regions as a result of climate change," von May said.

The researchers found that the frogs' tolerance to heat varied from 77 degrees Fahrenheit to 95 degrees and that, as expected, highland species tolerated much lower temperatures than lowland species.

Frogs living in high-elevation grasslands tolerated near-freezing temperatures, which they experience during the dry season, as well as moderately high temperatures, which they may experience during sunny days.

When considering the temperature of the microhabitats in which the frogs live, the results suggest tropical lowland species live close to their thermal limit. Amphibians living at high elevation might be more buffered from future temperature increases because the highest temperatures they can tolerate are farther away from the maximum temperatures that they regularly experience in the wild.

Von May is the first author of the Ecology and Evolution paper, "Divergence of thermal physiological traits in terrestrial breeding frogs along a tropical elevational gradient."

Citation
Rudolf von May, Alessandro Catenazzi, Ammon Corl, Roy Santa-Cruz, Ana Carolina Carnaval, Craig Moritz. Divergence of thermal physiological traits in terrestrial breeding frogs along a tropical elevational gradient. Ecology and Evolution, 2017; DOI: 10.1002/ece3.2929



Wednesday, March 15, 2017

Cobras - Cytotoxicity as a Defensive Innovation and Its Co-Evolution with Hooding, Aposematic Marking, and Spitting

Bryan Frye and a cobra.
A University of Queensland-led international study has revealed how one of the world's most feared types of snakes -- cobras -- developed their potent venom.

Associate Professor Bryan Fry of UQ's School of Biological Sciences said cobras were killers in Africa and Asia, and caused crippling social and economic burdens through the number of survivors who needed amputations due to the snake's flesh-eating venom.

"While we knew the results of their venom, how the cobra's unique defensive venom evolved remained a mystery until now," he said.

"Our study discovered the evolutionary factors shaping not only cobra venom, but also the ornate markings on their hoods, and the extremely bright warning colourings present in some species."

The research team studied 29 cobra species and related snakes, finding that the flesh-destroying venom first evolved alongside the broad hoods that make cobras so distinctive.

Dr Fry said further increases in the potency of the toxins subsequently occurred parallel to their warning strategies such as hood markings, body banding, red colouring and spitting.

"Their spectacular hoods and eye-catching patterns evolved to warn off potential predators because unlike other snakes, which use their venom purely for predation, cobras also use it in defence," he said.

"For the longest time it was thought that only spitting cobras had these defensive toxins in high amounts in their venoms, however we've shown that they are widespread in cobras.

"These results show the fundamental importance of studying basic evolution and how it relates to human health."

Dr Fry said the next step in the team's research was to conduct broad antivenom testing.

"Globally, snakebite is the most neglected of all tropical diseases and antivenom manufacturers are leaving the market in favour of products that are cheaper to produce and have a bigger market," he said.

"Antivenom is expensive to make, has a short shelf life and a small market located in developing countries.

"Therefore, we need to do further research to see how well those remaining antivenoms neutralise not only the toxins that kill a person, but also those that would cause a severe injury."

He said there may also be a benefit to this research in cancer treatment.

"Any kind of compound that selectively kills cells could be a good thing," Dr Fry said.

"These chemicals may lead to new cancer treatments if we can find ones that are more potent to cancer cells than normal healthy cells.

"Cobras are a rich resource of novel compounds in this way so there may ultimately be a silver lining to this very dark cloud."


Citation

Panagides N, Jackson TN, Ikonomopoulo MP. Arbuckle K, Pretzler R, Yang DC, Ali SA, Koludarov I, Dobson J, Sanker B, Asselin A, Santana RC, Hendrikx I, van der Ploeg H. Tai-A-Pin J, van den Bergh R. Kerkkamp HM, Vonk FJ, Naude A, Strydom MA, Jacobsz L, Dunstan N. Jaeger M, Hodgson WC, Miles J, Fry BG. 2017 How the Cobra Got Its Flesh-Eating Venom: Cytotoxicity as a Defensive Innovation and Its Co-Evolution with Hooding, Aposematic Marking, and Spitting. Toxins  9, 103.

Monday, March 13, 2017

Hypsiboas punctatus, the first fluorescent frog

Before and after. The polka-dot tree frog in natural light
 (top) and under UV (bottom.)Photo credit: Julian Faivovich
 & Carlos Taboada 
The first fluorescent frogs have been discovered in South America. The green fluorescence is due to a compound found in the lymph and skin glands of the polka-dot treefrog (Hypsiboas punctatus). At twilight, the phenomenon enhances the frogs’ brightness and may help them communicate with each other.

Fluorescence has previously been reported in fish, scorpions and birds, but never amongst the 7000 plus species of amphibians. The blue–green glow of the polka-dot tree frog was observed when they were under UV light and is linked to a new fluorescent compound, not previously known in nature. The compound absorbs light in the violet–ultraviolet region and emits blue–green light. Time-of-flight mass spectrometry showed that the main fluorescent compound was the molecule Hyloin-L1. NMR revealed an N-methyl-dihydroisoquinolinone core.

‘It is basically a benzamide with a methoxy group added on, which makes the absorption band fall on the edge of the visible spectrum,’ notes Andrew Beeby at Durham University, UK, who was not involved in the study. He adds that this ‘DayGlow frog’ adds to our growing awareness of bioluminescence. The isoquinolinone structure has never before been described in any animals, only in plants. The chromophore seems to be the cyclic benzamide.

‘This is very different from fluorophores found in other vertebrates, which are usually proteins or polyenic chains,’ says author Maria Gabriela Lagorio, a photochemist at the University of Buenos Aires, Argentina. ‘The chromophore itself is well known, but the class of the secondary compound is completely new,’ adds co-author Norberto Peporine Lopes, a natural product chemist at the University of São Paulo in Brazil.

Hyloin L-1 (H-L1) is the molecule that is principally responsible for the polka-dot tree frogs’ fluorescence, although the other molecules pictured also contribute Biologist Karen Carleton at the University of Maryland notes that like many colourful compounds, ‘it contains lots of carbon–carbon double bonds with lots of π electronics that can easily be excited at visible wavelengths. It is also similar to a compound like 11-cis retinal, which is the chromophore that our eye uses to absorb light.’

The discovery is a bolt out of the blue for most in the field. ‘We were not expecting this bio-fluorescence. It was an incredible surprise,’ says Lopes. He suspects the frog, which has translucent skin, uses the phenomenon to communicate. Lagorio agrees: ‘Amphibian species have photoreceptors in their eyes maximally attuned to blue and green vision, so we expect that these compounds enhance the brightness of these frogs under conditions of twilight.’ The team has now begun examining the polka-dot’s relatives. ‘We expect that this will be a more universal phenomenon with perhaps 100 or 200 species showing this property,’ says Lopes.

‘It would be interesting to investigate if [fluorescence] has a role in species recognition, or whether it facilitates the formation of couples,’ notes Bibiana Rojas, ecologist at the University of Jyväskylä, Finland. ‘Fluorescence would be potentially very useful in a noisy environment and in a habitat with dense foliage, as it would make individuals brighter.’

Citation

Taboada C, Brunetti AE, Pedron FN, Neto FC,  Estrin DA, Bari SE, Chemes LB,  Lopes NP, Lagorio MG, Faivovich J. 2017. Naturally occurring fluorescence in frogs. PNAS 2017 doi:10.1073/pnas.1701053114

Saturday, March 11, 2017

A new homalopsid snake from Myanmar

Gyiophis salweenensis Photo credit. Evan Quah
The 54th species of homalopid snake has been described by Quah et al. (2017). The new species, Gyiophis salweenensis was described from the lowlands of Mawlamyine District in Mon state, southeastern Myanmar. The authors suggest that Gyiophis salweenensis  is presumed to be closely related to G. maculosa Blanford and G. vorisi Murphy based on the similarities in scales and coloration but can be separated from G. maculosa by the shape of its first three dorsal scale rows that are square, ventral scale pattern that lacks a central spot, and a faint stripe on dorsal scale rows 1–4. It can be further distinguished from G. vorisi by its lower number of ventral scales (129 vs. 142–152), lower number of subcaudals (30/29 vs. 41–58), narrow rostral scale, and having more rows of spots on the dorsum (four vs. three). A preliminary molecular analysis using 1050 base pairs of cytochrome b (cytb) recovered G. salweenensis  as the sister species to the Chinese Mud Snake (Myrrophis chinensis). G. maculosa and G. vorisi were unavailable for the analysis. The discovery of G. salweenensis sp. nov. highlights the need for more surveys into the herpetological diversity of eastern Myanmar which remains very much underestimated.

Citation
Quah ES, Grismer LL, L Jr PE, Thura MK, Zin T, Kyaw H, Lwin N, Grismer MS, Murdoch Ml. 2017. A new species of Mud Snake (Serpentes, Homalopsidae, Gyiophis Murphy & Voris, 2014) from Myanmar with a first molecular phylogenetic assessment of the genus. Zootaxa. 4238(4):571-82.

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.