Thursday, October 24, 2013

Atrazine, Bd, and frog survival

Using the invasive Cuban treefrog, Osteopilius septentrionalis
Rohr et al. studied the effects of atrazine on frogs exposed to Bd.
The combination of the herbicide atrazine and a fungal disease is particularly deadly to frogs. USF Biologist Jason Rohr said  new findings show that early-life exposure to atrazine increases frog mortality but only when the frogs were challenged with a chytrid fungus (Bd), a pathogen implicated in worldwide amphibian declines. The research is published in the new edition of Proceedings of the Royal Society B.

"Understanding how stressors cause enduring health effects is important because these stressors might then be avoided or mitigated during formative developmental stages to prevent lasting increases in disease susceptibility," Rohr said.

The study was conducted by Rohr and Lynn Martin, Associate Professors of USF's Department of Integrative Biology; USF researchers Taegan McMahon and Neal Halstead; and colleagues at the University of Florida, Oakland University, and Archbold Biological Station.

Their experiments showed that a six-day exposure to environmentally relevant concentrations of atrazine, one of the most common herbicides in the world, increased frog mortality 46 days after the atrazine exposure, but only when frogs were challenged with the chytrid fungus. This increase in mortality was driven by a reduction in the frogs' tolerance of the infection.

Moreover, the researchers found no evidence of recovery from the atrazine exposure and the atrazine-induced increase in disease susceptibility was independent of when the atrazine exposure occurred during tadpole development.

"These findings are important because they suggest that amphibians might need to be exposed only to atrazine briefly as larvae for atrazine to cause persistent increases in their risk of chytri-induced mortality," Rohr said. "Our findings suggest that reducing early-life exposure of amphibians to atrazine could reduce lasting increases in the risk of mortality from a disease associated with worldwide amphibian declines."
Until this study, scientists knew little about how early-life exposure to stressors affected the risk of infectious diseases for amphibians later in life.

"Identifying which, when, and how stressors cause enduring effects on disease risk could facilitate disease prevention in wildlife and humans, an approach that is often more cost-effective and efficient than reactive medicine," Rohr said.

The findings are also the latest chapter in research Rohr and his lab has conducted on the impact of atrazine on amphibians. These findings are consistent with earlier studies that concluded that, while the chemical typically does not directly kill amphibians and fish, there is consistent scientific evidence that it negatively impacts their biology by affecting their growth and immune and endocrine systems.

Citation
J. R. Rohr, T. R. Raffel, N. T. Halstead, T. A. McMahon, S. A. Johnson, R. K. Boughton, L. B. Martin. Early-life exposure to a herbicide has enduring effects on pathogen-induced mortality. Proceedings of the Royal Society B: Biological Sciences, 2013; 280 (1772): 20131502 DOI: 10.1098/rspb.2013.1502

Sunday, October 20, 2013

Mechanism of the chytrid fungus

A fungus that is killing frogs and other amphibians around the world releases a toxic factor that disables the amphibian immune response, Vanderbilt University investigators report Oct. 18 in the journal Science.

The findings represent "a step forward in understanding a long-standing puzzle -- why the amphibian immune system seems to be so inept at clearing the fungus," said Louise Rollins-Smith, Ph.D., associate professor of Pathology, Microbiology and Immunology. Although the identity of the toxic fungal factor (or factors) remains a mystery, its ability to inhibit a wide range of cell types -- including cancerous cells -- suggests that it may offer new directions for the development of immuno-suppressive or anti-cancer agents.

The populations of amphibian species have been declining worldwide for more than 40 years. In the late 1990s, researchers discovered that an ancient fungus, Batrachochytrium dendrobatidis, was causing skin infections, and the fungus is now recognized as a leading contributor to global amphibian decline.

Rollins-Smith, an immunologist, and her colleagues have been studying the immune response to the fungus for more than 10 years. "Amphibians have excellent and complex immune systems -- nearly as complex as humans -- and they should be able to recognize and clear the fungus," she said.

In early studies, the investigators demonstrated that some frogs produce anti-microbial peptides in the skin that offer a first layer of defense against the fungus. But when the fungus gets into the layers of the skin, Rollins-Smith said, the conventional lymphocyte (immune cell)-mediated immune response should be activated to clear it.

They found in the current studies that recognition of the fungus by macrophage and neutrophil cells was not impaired. "We think it's not a block at the initial recognition stage," Rollins-Smith said. "The macrophages and neutrophils can see it as a pathogen, they can eat it up, they can do their thing."

But during the next stage of the immune response, when lymphocytes should be activated, the fungus exerts its toxic effects. The investigators demonstrated that B. dendrobatidis cells and supernatants (the incubation liquid separated from the cells) impaired lymphocyte proliferation and induced cell death of lymphocytes from frogs, mice and humans. The toxic fungal factor also inhibited the growth of cancerous mammalian cell lines.

The toxic factor was resistant to heat and proteases (enzymes that cut proteins into pieces), suggesting that it is not a protein. It appears to be a component of the cell wall, because drugs that interfere with cell wall synthesis reduce its inhibitory activity and because the zoospore -- an immature form of the fungus that lacks a cell wall -- does not produce the factor.

The new findings suggest the possibility that toxic factors -- in addition to acting locally to inhibit the immune response -- might also get into the circulation and have neurotoxic effects, Rollins-Smith said.

"Fungal infection causes rapid behavioral changes -- frogs become lethargic and start to crawl out of the water -- suggesting that even though the fungus stays in the skin, the toxic material is having effects elsewhere."

The studies, led by graduate students J. Scott Fites and Jeremy Ramsey, could also suggest new conservation measures for species that may be medically important.

"Amphibian skin has long been favored in folklore for its medicinal properties," Rollins-Smith said. "Frogs are a rich source of potentially useful molecules that might work against human pathogens."

Citation
J. S. Fites, J. P. Ramsey, W. M. Holden, S. P. Collier, D. M. Sutherland, L. K. Reinert, A. S. Gayek, T. S. Dermody, T. M. Aune, K. Oswald-Richter, L. A. Rollins-Smith. The Invasive Chytrid Fungus of Amphibians Paralyzes Lymphocyte Responses. Science, 2013; 342 (6156): 366 DOI: 10.1126/science.1243316

Wednesday, October 16, 2013

Variability in the venom proteome of juvenile Bothrops jararaca

Bothrops jacaraca juvenile. Photo credit: Fernando Tatagiba
Snake venoms are complex mixtures but it is important that we understand them so that we can develop effective antivenoms. For snakes of the viper family, a number of studies have illustrated that the picture is complicated by the fact that the venom composition can vary between members of the same species. These changes are inherited, so have a genetic background.

However, the snake venom of individual viperids also changes with the age and diet of the creatures, so there are other factors at play. These so-called ontogenetic effects are particularly striking in the jararaca, one of the most abundant venomous snakes found in Brazil, which causes many deaths in the local population. This snake, Bothrops jararaca, has caught the attention of Brazilian researchers who have been studying variations in the venom.

Solange Serrano and colleagues from the Butantan Institute, Sao Paulo, and the University of Sao Paulo have found that the proteome of young jararacas differs from that of adults, and that there are gender differences in the venoms too. However, there have been very few studies on juvenile jacaracas, so they undertook a comprehensive proteomic study of the venoms of young snakes in order to define any compositional differences that occur as the juveniles grow.

The research team selected 21 young specimens of Bothrops jacaraca that were born to 10 different mothers originating from different geographical regions of Brazil, all of which were within the states of Sao Paulo, Minas Gerais and Santa Catarina. The mothers were housed in the same lab so that the young could be brought up on exactly the same diet and environmental conditions, to rule out the ontogenetic influences.

Venom was milked from the snakes over 9 months and the proteins were subjected to Western blotting using polyclonal antibodies raised against venom metalloproteinases (SVMPs) and serine proteinases (SVSPs). They were also separated by SDS-PAGE and the proteins in each band were identified by tandem mass spectrometry by searching against the NCBI Serpentes database.

The various properties associated with different venom components, such as caseinolytic, amidolytic and coagulant activity and prothrombin activation, were also investigated and compared between the individual snakes as they matured.

The protein profiles of the snakes showed a wide variation between individuals regardless of gender or the geographical origin of their mothers, even for the eight that were born to the same mother. In addition, the degree of glycosylation of the venom proteins varied between individuals and this was supported by the variations between SVMPs and the SVSPs.

Some of the activities of the venom were similar between snakes while others varied markedly. The abilities to break down casein and activate prothrombin were comparable whereas the amidolytic properties and the plasma coagulant activity differed strongly. So, the variation in the ability to clot the blood of victims, which is a characteristic feature of jararaca venom, cannot be attributed to age, gender or diet and is likely to be a genetic trait.

Although there were large differences in the actual protein compositions, especially within most of the principal toxin classes, there were some areas on the SDS-PAGE bands which were conserved between individuals. For instance, the region corresponding to proteins of molecular mass 45-50 kDa contained SVMPs and L-amino acid oxidase. For 10 venoms, aminopeptidase A was also identified for the first time in the venom of this snake.

A small tripeptide of composition ZKW was also detected in all venoms. This component inhibits SVMPs and acts to prevent the uncontrolled breakdown of proteins within the venom gland.

So, there appears to be a central core of components that are conserved across all jararaca venoms but there are also large variations in the protein compositions. The lack of influence of gender and geographic origin was confirmed by a multivariate analysis. Overall, the findings point strongly to genetic inheritance as the major factor in determining venom composition in juvenile Bothrops jararaca snakes.

Citation
Gabriela S. Dias, Eduardo S. Kitano, Ana H. Pagotto, Sávio S. Sant’anna, Marisa M. T. Rocha, André Zelanis, and Solange M. T. Serrano 2013. Individual Variability in the Venom Proteome of Juvenile Bothrops jararaca Specimens Journal of Proteome Research 2013 12 (10), 4585-4598

Friday, October 11, 2013

New study supports the idea that Cerberus schneiderii is an abundant coastal species

Preliminary studies suggest that Schneider's Bockadam (also known as the dog-faced water snake), Cerberus schneiderii, is one of the most abundant aquatic snakes in mangrove ecosystems across most of Southeast Asia, A new study of this snake at the Sungei Buloh Wetland Reserve in Singapore supports these studies. The brackish man-made ponds at this site do not dry up and they are the source of abundant and continuous food supply to the snakes that inhabit the wetland. The year-round supply of food and climatic conditions allow this snake to grow and reproduce year round. Chim and Dion (2013) conducted monthly surveys at the man-made brackish ponds throughout 2006 and estimated population density  at 102 snakes per hectare and snake biomass at 4.1 kg per hectare. They report relative abundance at 5.4 snakes per man-hour, all  providing evidence of a large Cerberus population at the study site.  A wide range (145–720 mm SVL) of body size were present, and  neonates were rarely encountered. Adult females reach sexual maturity at a body size of 336 mm and the authors found  no seasonal variation in the population’s size structure, suggesting that recruitment occurred throughout the year. Most of the snakes were sedentary and more than 90% of them remained in the same pond that they were captured for the first time. During low tides, snakes had a tendency of congregating in relatively  deep water close to the sluice gates and in the network of tidal streams and pools in the man-made ponds.

Citation
Chim, C. K., & Diong, C. H. (2013). A MARK-RECAPTURE STUDY OF A DOG-FACED WATER SNAKE CERBERUS SCHNEIDERII (COLUBRIDAE: HOMALOPSIDAE) POPULATION IN SUNGEI BULOH WETLAND RESERVE, SINGAPORE. THE RAFFLES BULLETIN OF ZOOLOGY, 61(2), 811-825.

Friday, October 4, 2013

Suizo Report -- To Gus, With Love

Howdy Herpers,                                                         10/3/13

“And when I die, and when I’m gone, there will be one child born in a world to carry on, ......to carry on.” Blood, Sweat and Tears, Columbia Records, 1969

We’re going to go Hollywood with this report. At times, the snakes on our plot demonstrate drama on that sort of scale. We witness sex and violence, interwoven with epic struggles to survive in a land that has barely enough to scratch out a living. Paradise is a nice place to visit, but you wouldn’t want to live there. They have no choice but to make a go of it.

We focus on two snakes with this report. Both are Black-tailed Rattlesnakes (Crotalus molossus). One is a male, CM11, “Gus,” and the other is a female, CM17, “Ms. Gus.”
The slithering duet has much in common, as far as snakes go. They’re both the same species, occupying the same patch of ground. They eat the same prey items, and seek similar shelters. Both have overcome astronomical odds in order to survive to adulthood.  And they both have exceptionally fat heads. Their fat heads are what make them the ideal couple.
 Gus first came our way on 17 September of 2011. At the time, we had little use for a skinny male molossus with a fat head. We’d been there, done that, and had next to nothing to show for it. Hence, he donated some blood, received a PIT tag, and then came the customary unceremonious dump back to his place of capture. He was not even Gus at that point in time. As far as we were concerned, that should have been the end of him.



But then the recapture transpired. On the evening of 3 August 2012, Gus was bagged again. A wave of the PIT tag reader told us who he was. By this point in time, our mission was to put a transmitter into any and all molossus that crossed our path. For whatever reason, our surgeon, Dr. Dale DeNardo, took compassion on this snake. He felt compelled to name this snake after his fat-headed dog, Gus. One must, at times, go to great lengths to take care of the hands that take of them. In short order, Gus was in the game, performing great deeds of Gus-dom. For a scrawny, fat-headed snake, he really got around!  

On 16 September of 2012, Marty Feldner led the field class of Wolfgang Wuster on a Roger-less outing. Gus was found paired with a female­ the future Ms. Gus. The first glimpse of Ms. Gus inspired Marty to comment: “Yegads! Her head is even fatter than his!”  At that point in time, we were out of transmitters. Ms. Gus was left alone that night. As soon as I got wind of the pairing, a rush order for a new transmitter was placed. And the directive was that until we got the transmitter, we were to leave the pair alone. If we were to ever get reproduction of the species on our plot, mating had to ensue.



My first visual of the pair was on the evening of 28 September. They were in a miserable snarl of a packrat midden that was packed into the root system of a particularly sinister and sprawling catclaw acacia. The thorny hell hole was nicely accentuated by a ring of chest high prickly pear which all but blocked the view in. Much blood was lost in trying to get a visual of Ms. Gus. When I finally did see her, I also was inspired to say: “Yegads! Marty is right! Her head is fatter than his!”  

The game of cat and mouse between the fat-headed snakes and their fat-headed trackers continued until the evening of 5 October. That night, Marty and I had split the tracking duties, and Marty had Gus on his route. At 8:09 PM, Marty summed up what he saw nicely by flatly stating on the datasheet: “It is good night to fornicate!” (He didn’t actually write “fornicate.” He used the foo foo word! Cussing on a datasheet? Shame on you, Marty…….)



Despite the rather abrasive start to the words Marty scrawled on the page that night, the rest of the description is as fluid and smooth as the action he witnessed. He wrote:

“CM11 is in coitus with a female (equivalent to his size and maybe heavier) at the edge of a staghorn cholla midden constructed in prickly pear. When first seen, CM11 was head jerking and chin rubbing along flank of unknown female. He continued this behavior on and off for 8-10 minutes until female moved to investigate me. This is when the tails became exposed and I could see for certain that they were locked up. Female dragged him by his wang so they were stretched out in opposite directions, weaved through the prickly pear over the next few minutes. CM11 worked his way back to female and resumed chin rubbing flanks and dorsum, taking breaks periodically to lie motionless and enjoy contemplating which hemipene he was using. Tongue flicking accompanying most chin-rubbing motions.”

Did you guys catch these words?

“FEMALE DRAGGED HIM BY HIS WANG? TAKING BREAKS TO ENJOY CONTEMPLATING WHICH HEMIPENE HE WAS USING?”

How you talk, Feldner!

But just in case, that would be the right hemipene, Gus. Does he know his right from his left? I’ll bet he did on this night!



All joking aside, Marty’s write up of this incident was pure artistry. Working at night with nothing but a headlamp, a clipboard, a pen, a vivid imagination, and a blank page to fill is an arduous process. And the lure of what comes next is always strong with many animals on the list to check. To his credit, he stayed with it.

And so did Gus! The next morning, Mr. Feldner and I did not let any grass grow under our feet getting back to the spot where the action was transpiring. We arrived at 7:55 AM to see that the pair was still “locked up.” This is where our scruples might very well have been in the way of gaining a new study animal. My rules for capture of a new snake do not allow for breaking up a couple that is fu, er uh, fornicating. We were prepared for a long wait. They had already been at it for 12 hours, and could easily go another 12 before it was over. 

But then Ms. Gus did us the ultimate favor. Upon seeing us looming large above her, she panicked, and began sprawling pell-mell toward the entrance to the Neotoma midden that Marty described. Poor Gus was still in her, so to speak, and was haplessly wrapped like an anchor about the prickly pear. Ms. Gus began a series of jerking motions, (yehaw!), trying to get free, but she only gained an inch or so. (Gus’s “wang” also likely gained an inch or so in the process). With a powerful surge, Ms. Gus broke free, literally hanging Gus out to dry in the process.

With Ms. Gus now unconnected, Roger’s rules for breaking up a couple no longer applied. She was snagged and bagged, and female CM17 was now in the game! That’s the end of that story ­and the beginning of the next.

We of course had to take Ms. Gus home with us for a couple days, in order to line up and perform a surgery. This left hapless Gus to smoke his after-sex cigarette alone, and maybe get “righty” back into its proper moorings. After that, he was off to the races. There was no need to be hanging around. The pencil necks had just taken his fu, er uh, his forn, er uh, his mate. No sense in waiting on whatever would come of that flandickery. He bombed across Suzio Wash, and made a major shift along the southern flank of the Suizo Mountains. While there were occasional signs of settling in at a couple places, he never actually hibernated. He stayed on the go throughout the winter, and eventually had moved further north and east than any other animal on our plot. The dude was a machine!


By the time we got Ms. Gus back to her capture spot, Gus was long gone. While it is unlikely that she was pining for her man, she remained at her site 1 for what seemed like two for evers. Finally, on 4 November, she had jetted across the wash, and was near the top of the extensive southwest ridge of the Suizo Mountains proper. She eventually went over top, and dropped into the lower bowels of Tim Canyon. She was viewed surface-active until 4 December. She was very thick in girth at that point. With the next tracking session, 8 December, she had slipped into an impressive and extensive west-facing boulder structure. It was here that she hibernated, and was not seen again until 11 March of 2013.


The author of this epic report decided that a thorough description of the hibernaculum of Ms. Gus is in order. This is not because your author is so fond of typing that he wants to aimlessly go about whittling his fingers to the second knuckle describing a rock pile with a cold snake in it. (Although that is certainly reason enough for the effort). No, this hibernaculum is to play a big role in what follows with this report.

Two paragraphs ago, mention was made of a place called Tim Canyon. This canyon is the southernmost of three different slot canyons that drain the western side of the Suizo Mountains. As one approaches the canyon from the west, it rumbles gently upward in eastward fashion for a distance of about 300 meters. The canyon then bends abruptly, steepens in aspect, and heads upward and northward as one continues the ascent. It eventually peters out, and becomes a steep, south facing flank of the third highest point in the Suizos.

Ms. Gus chose to hibernate at the point where Tim Canyon makes the bend. She was 30% up the east flank of the adjacent slope. The granitic bedrock structure that she selected is roughly three meters tall and nearly perpendicular to the slope, by perhaps three meters wide, and roughly forty  meters long south-to-north. The top portion of this site is actually imbedded in the soil, but the bottom has many crevices and soil holes that lead eastward into its embrace. Lush vegetation grows just west of the bottom of this structure. In short, it was a good place for a fat-headed molossus to be.  


Upon emerging from hibernation, Ms. Gus made a series of mini moves that at first led us to believe that she was going to leave Tim Canyon. She seemed to be retracing her autumnal movements. But once she got to near the top of the southwestern ridge, she began to slip back down again. By 29 June, she was back at her hibernaculum. Marty was able to get two visuals of her in July. With each of these visuals, he commented on how thick she had become toward the rear. 

I did not see her again until 3 August. Up until 3 August, she had remained at her hibernaculum. But with what turned out to be pure serendipity on my part, I found that she had moved about 30 meters northward, along the lower edge of her structure. She was found coiled in a shallow soil escarpment at the northernmost reach of the structure. I had time to squeeze off one photo of her coiled in situ. Then, she bolted into a hole that was just behind her. I squeezed off two more shots of her hefty rear flank before she could slip out of sight. She was, without question, a very pregnant molossus. And this was to be the last time we saw her pregnant. 

By 7 August, she had made a ping pong move back to her hibernaculum. She was not visible, as usual. Two days later, the ever lucky Marty Feldner discovered a male neonate molossus out crawling on top of one of the boulder stacks, less than two meters from where she had hibernated. In short, her hibernaculum was the same place as her parturition site! While this is a common occurrence with many species of rattlesnakes at higher elevations, it is an absolute first for us. This out of 12.5 years of observing birthing with three species of rattlesnake!

Marty and I had not discussed what to do if we encountered any neonates. Hence, on 9 August, he made the executive decision to collect it. His rationale was one of getting DNA from the little fella. There was no hot surge of joy when, on the morning of 10 August, Marty showed me his little prize. I was of course stoked that we had our first birthing incident with molossus, but I had these dreams of seeing piles of babies hanging out with mommy. If we went wading in and removing them as we found them, no such thing would happen. 


Marty was off to other lands in the week that followed. This left me with the nest site of Ms. Gus all to myself. Poor me! There would be no more taking babies from mamma! Needless to say, I hit that rascal morning and night for the next week to follow. I became the invisible man at work and at home. I’d go out and stay out until midnight, get up the following morning at 4 AM and hit it again. While I was doing that, reports and images came trickling in from other parts of the country. In all, three other groups had nesting molossus, and all three got great images of mothers with babies. That’s right, I had these KIDS upstaging me! I was walking a mile a day, twice a day, to attempt to get what they had going on at their back porch. This would have been acceptable if only I got some of the action that should have been my reward.

Nope, when all was said and done, on 12 August, I found one neonate molossus that I had no business finding at all. It was found in a narrow vertical crevice just outside what was determined to be the preferred entrance hole to the nest. Mamma was viewed out basking at this entrance hole on 14 August. Back home, the neonate that Marty had collected shed his skin this day. I took him out to release him at the nest site on 15 August, and captured a Tiger Rattlesnake that was hidden in some trixis and prickly pear close to one of the nest entrances. (I never would have found this tiger were I not scouring the vicinity for neonates). By 16 August, Ms. Gus had cleared out of her nest site, and her birthing experience was behind us. There were to be no cool images of mom and babies hanging out together. No neonate shed skins were found in or around the nest site. While it could have all been worse, despite all the effort, our first molossus birthing experience was a rather lackluster affair. We had a fat snake that morphed into a skinny snake, and two neonates that proved the nesting experience had actually happened.



We did not track Ms. Gus again until 24 August. By this time, she had crawled out of the bowels of Tim Canyon, and was hanging around a wash just east of Iron Mine Hill. It was this wash that Marty first saw her and Gus together. Once she was in this vicinity, I knew it would only be a matter of time before Gus found her. We ramped up our efforts on these two animals accordingly.

For nearly a month, Gus showed no interest in tracking his lady down. They were about 200 meters apart on 31 August, but that was as close together as we saw them. And then, on the evening of 20 September, Dale DeNardo and I tracked Ms. Gus. We found her out crawling in a southerly direction, at the western base of a bump in the bajada that we call “Little Hill.” After tracking her, we joined Marty’s group just as he was finishing the write up of Gus. He was just south of Suizo Wash, close to the northern flank of Iron Mine Hill. He was once again around 200 meters from his lady.

The morning of 22 September found Gordon Schuett, Ryan Sawby, and me close to where Gus had been tracked a day and a half previous. Upon raising the antenna skyward, it was noted that his signal was leading us directly toward where Ms. Gus had last been seen. As we followed the blips, the route was taking us right to the west flank of Little Hill. He seemed to be heading straight for his bride. The flag for Ms. Gus waved in the breeze, just 30 meters to the south. Reunited? Hot diggity damn! Anticipation caused me to ignore the signal, and head for the flag. It was then that it all came to an abrupt end.

“Wait a minute, Roger!” Gordon sounded off from behind me. “Is this what we’re tracking?” As he made the inquiry, he deftly hooked a section of snake flank from out of a prickly pear. It was Gus, or rather, what was left of him.

The 600mm of flank that Gordon had flipped out of the prickly pear was upside down, on open, rocky bajada. Hence, my first glimpse was of the white belly scales facing up. Moderate sized black ants were working both ends of the severed corpse. There was no head or tail to be found in the vicinity, just the hefty mid flank. What remained was fresh, there was no stench, and the ants had barely begun the cleanup process. He had not been dead long.

Next came the photographs, the gut-wrenching mortality write up, and the wild speculation as to how this had happened. Gordon and Ryan heavily favored human predation. My own theory was that this was a natural event. A Harris Hawk was viewed perched high on a nearby mesquite. As we don’t really know for certain what got him, there is no need to belabor the point. What we do know is that a very favored subject of ours is no longer with us. We had grown quite attached to our skinny, fat-headed and randy molossus. You will be missed, Gus.
Meanwhile, in a hallowed drawer of my refrigerator, stowed in a sealed plastic bag is a 300mm plus long full shed skin of a neonate male molossus. Sealed within that bag is a notecard that refers anybody interested to page 19 of the DNA section of the official three-ringed binder of the Suizo Mountain Project for 2013. Page 19 contains all the vitals on this snake. And what the scribe did not capture, the camera did. We have nailed this lad nine ways to Sunday.

 Is this the son of Gus? He sure does have a fat head! This author thinks he is indeed the son of Gus. Will he “carry on?” Though the odds are against him, this author sincerely hopes he does. Will we get him back someday? Maybe!  Will we know him if we do get him? Maybe! Would we have any hope of knowing who he is if Marty had not picked him off from the nest site? No way! 


In light of the full developments of this tale, you done splendid, Mr. Feldner. Let’s hope that one of us lives long enough to see this all draw to a successful conclusion.

This here is Roger Repp, signing off from Southern Arizona, where the turtles are strong, the snakes are handsome, and the lizards are all above average.  






Sunday, September 29, 2013

Evidence for a Triassic origin for Lepidosauria


Top: Vellberg jaw. Bottom: restoration image.
 Illustration Credit: Marc Jones.
Two new fossil jaws discovered in Vellberg, Germany provide the first direct evidence that the ancestors of lizards, snakes and tuatara (known collectively as lepidosaurs) were alive during the Middle Triassic period -- around 240 million years ago.

The new fossil finds predate all other lepidosaur records by 12 million years. The findings are published in BMC Evolutionary Biology.

The international team of scientists who dated the fossil jaws have provided evidence that lepidosaurs first appeared after the end-Permian mass extinction event, a period when fauna began to recover and thrive in the more humid climate.

Lead author Dr Marc Jones, who conducted the research at UCL, explained: "The Middle Triassic represents a time when the world has recovered from the Permian mass extinction but is not yet dominated by dinosaurs. This is also when familiar groups, such as frogs and lizards, may have first appeared."
The small teeth and lightly built jaws suggest that the extinct animal preyed on small insects. The new fossils are most closely related to the tuatara, a lizard-like reptile.

Tuatara can be found on 35 islands lying off the coast of New Zealand and were recently reintroduced to the mainland. However, they are the sole survivors of a group that was once as globally widespread as lizards are today. Tuatara feed on beetles, spiders, crickets and small lizards, also enjoying the occasional sea bird.
Today, there are over 9,000 species of lizards, snakes and tuatara. Knowing when the common ancestor of this grouping first appeared is crucial for understanding the ecological context in which it first evolved as well as its subsequent diversification.

To establish the age of the fossil remains, biologists use a dating technique known as a "molecular clock." This method compares the amount of genetic divergence between living animals, caused by changes in their DNA sequences that have accumulated since they split from a common ancestor. These mutations occur fairly regularly, ticking along at a clock-like rate. However, for the clock to convert genetic differences into geological time, it has to be calibrated using one or more fossils of known relationship and time.

Molecular clocks have been used by biologists to answer questions as important as when the first modern humans emerged, and when humans and chimpanzees shared a common ancestor. The new fossil jaws can improve molecular dating estimates of when reptiles began to diversify into snakes, lizard and tuatara, and when the first modern lizards inhabited the earth. Previous estimates have varied over a range of 64 million years and the team are keen to help narrow this down.

"Some previous estimates based on molecular data suggested that lizards first evolved 290 million years ago," said second author Cajsa Lisa Anderson, University of Gothenburg. "To a palaeontologist this seems way too old and our revised molecular analysis agrees with the fossils."

Revised molecular dating in light of this new fossil find now suggests lizards began to diversify into most of the modern groups we recognize today, such as geckos and skinks, less than 150 million years ago in the Cretaceous period, following continental fragmentation.

The specimens were collected and initially identified by Professor Rainer Schoch from the Staatliches Museum für Naturkunde in Stuttgart, where the specimens are now registered.

Scientists anticipate that the Vellberg site will yield yet more fossil discoveries in the future, broadening our knowledge of the vertebrate fossil record.

Co-Author Professor Susan Evans, from the UCL Department of Cell and Developmental Biology, said: "The fossil record of small animals such as lizards and frogs is very patchy. Hopefully, this new fossil site in Germany will eventually give us a broader understanding of what was going on at this time."

Citation

Jones MEA, Aderson L, Hipsley CA, Müller J, Evans SE,  Schoch RR. 2013. Integration of molecules and new fossils supports a Triassic origin for Lepidosauria (lizards, snakes, and tuatara). BMC Evolutionary Biology, 13 (1): 208 DOI: 10.1186/1471-2148-13-208

The Second Trinidad Buioblitz

The second annual Trinidad Bioblitz has come and gone.  This year it was held in the very biodiverese Arima Valley, with the base camp at the Asa Wright Nature Center. The preliminary tally of species was - Vertebrates 139, Invertebrates 247, Fungus 30, Diatoms 7, Plants 317 for a grand total of 740 species!

Teams include: Mammals, Freshwater (Fish, Aquatic Insects, Crustaceans), Amphibia and Reptilia, Birds, Molluscs, Spiders and other Arachnids, Butterflies and Moths, Social Insects, Myriapods millipedes/ centipedes) and Worms, Flowering Plants, Ferns, Lichens, Orchids and Fungi.

The Arima Valley has been the crown jewel for Trinidad's biodiversity for centuries, the site has been the geographical location for much of the scientific research that has occurred on Trinidad including classic studies of bats, guppies, and the herpetofauna as well as many other higher taxa. However, active quarrying operations threaten the habitat, and the activity of bush meat hunters threaten larger animal populations. But, perhaps the most significant sign that the valley is under development - the installation of sidewalks along the road.

But, the Bioblitz results suggest the flora and fauna are doing well at least for the moment. Teams of experts and volunteers  searched the valley for 24 hours attempting to identify as many species as possible. But, it can be more than just a list, because the opportunity of natural history observations is under every log and in every fruiting tree.

 Informational displays by various groups including the Trinidad and Tobago Field Naturalist Club, UWI Zoology Museum, Asa Wright Nature Center and Wildlife Division were present to  inform the public. So what about the herpetofauana. Here are some photos of what was found.

An Arima Valley Bothrops cf asper. was sitting in the vegetation close to a
 chorus of Hypsiboans crepitans.
Top: a juvenile Chironius carinatus, bottom Chironius (Macrops)
septentrionalis. Both juveniles and very difficult to distinguish
from each other, but look at the relative size of the eyes

Hypisboans crepitans hiding in the vegetation during the day.

Epictia tenella was found climbing a tree trunk, it was about a meter
off the ground and was probably headed for a rotten liana filled with
termites.

A juvenile Oxyrhopus petolarius

Anolis planiceps sleeping on a leaf.

A male Gonatodoes vittatus perhaps the most common seen
reptile during the Bioblitz
The leaf-nesting frog, Phyllomedusa trinitatus



Friday, September 13, 2013

Suzio Report, Summer Fun

Howdy Herpers,                                                         9/12/13

Well friends, it has been too long since Typing Boy here has addressed you. I trust that the lack of reports lately has not caused too much angst in your lives?

So much has happened since Marty found that little tortoise in the black widow spider web that I hardly know where to begin. I do know that this had better be good, and my face now retains the red marks of a severe bitch-slapping from my own hand. There are 2600 reasons to shine now. Wake up and address these people, Roger! And make it count. Dammit!

As some of you know, the Herp Accountant here has been keeping close tabs on every turtle, snake, and lizard that he encounters. In some cases, the counts go back to 1989. But the common lizard numbers did not begin in earnest until the year 2000. It is that 12 plus year time period, along with the common lizards, that are going to be discussed next.

While every herp found is enshrined in my hallowed herp journal, there are really only six species of lizard that I consider indicators of how good or bad a herp year is. Experience has taught me that these wiggly little suckers, to varying degrees, are the herps that clearly demonstrate how good or bad a year can be.  Without further adieu, these six species are Zebra-tailed Lizards, Side-blotched Lizards, Whiptails, Desert Spiny Lizards, Regal Horned Lizards, and, of course, Gila Monsters. There is another number that plays as a wild card in my judgment of a herp year. That is the total number of lizards encountered.

The same system is used on snakes and turtles. We are not going to talk all that much on these except for one thing: 2013 is heading toward the worst herp year that I’ve ever had for snakes. At the end of August, 160 snakes were logged. My worst snake year ever was 221, and that was in 2002. Unless things pick up mightily, the lamenting in the year-end report for the Tucson Herpetological Society Journal is going to be impressive in both content and duration. (And if you want to see that report, you will have to become a member of the THS. Cough up your 20 bucks, pikers!).

Now that we have discussed what is bad in 2013, can we move on to the good? Great! Let’s mow these lizards down in order. For the Zebra-tailed Lizards, my best year of the century was 1,519. That was in 2008. With two months of possible encounters remaining, (they shut down by early November), the number for 2013 is 1,398. Already, 2013 is the second best year of the century. Will we beat 2008? Time will tell! With the Side-blotched Lizards, unless hordes of them suddenly rain down upon us, we will wind up with only slightly above average numbers. No big deal. Their best use is conversion to Lyresnake mass. Hopefully, that’s where they all went this year. We’re done with the likes of them. With the Whiptails, (several species), we have already broken the record set last year. That number was 453. We are now at 575! In 2008, I encountered 137 Desert Spiny Lizards. The count for these chunky fat heads is currently 108, which is 35 above average over the time period under discussion. Again in 2008, 20 Regal Horned Lizards were found which I crowed mightily about at the time. In 2013, the number now stands at 23, with more incoming expected. This is a record-breaker for one of the lizards that I love most! Last year, a record number of 32 Gila Monsters were encountered. At this point in 2013, we are at 25. We are already at the third best year of the century with these numbers, and again, more incoming is expected. Last, but not least, the wild card. Again, in 2008, the all species of lizard count was 2,978. This year, we are at 3,043! If we did not see one more stinking lizard for the remainder of the year, we are still walking in tall cotton.

We will stop with this type of herpetological bean-counter talk here, and move on to the hard-wired snakes under watch in paradise. Before my emailed leg-hump of late, we had 14 different rattlesnakes under watch, and were facing the prospect of cutting some of those out of the game. Thanks to what I am now calling the 2600 club, our N is now 17. And we expect to bump that to 20 by the end of this month. Yes sirs and madams, 20 transmitters will soon be merrily blipping across a swath of remote Sonoran Desert Thornscrub 2 kilometers long by 1 kilometer wide. When we fire up those receivers, we will not know whether to defecate, or go blind. This is called “fun.”  The thrill of mowing down 20 rattlesnakes whilst hoofing through a sticker-infested wonderland is mother’s milk to the few, the proud, the geeks! Thanks guys! And come on out to play with us sometime………

As much as Typing Boy would like to show you each and every snake that we have out there now, that is not possible. Truth be told, some of the newer snakes have yet to reveal themselves for good, in situ images. A case in point is our newest snake, CA134, a young male atrox. We released him on the evening of 31 August. I did not track him for the first time until 7 September. His signal was coming from the center of a flat, heart-shaped slab of gneiss. When I looked into the soil entrance, I saw two large adults looking back out at me. CA134 was behind these two­ no doubt stuck until they decide to leave. Right off the bat, he leads us to a mini aggregation. Sensational!  

Until now, I have made no mention of a little sweetheart of a female molossus that is under watch. She is CM18, as yet un-named. She is just shy of 2 feet long, and her rattle count is basal, 4 segments, and a button. Marty found her hanging out with our pregnant molossus CM17. Mother, daughter? Time will tell, I just hope that the DNA gets processed in my lifetime so that we will know for sure. The first image in this report is of her. We released her on 10 August, and with the first tracking on 14 August, she has scored a meal. Bully for her!

Speaking of scoring meals, Mr. Feldner was blessed to observe, and subsequently photograph, our female tiger CT13 track down and consume a pocket mouse. See image number 2. Following her feast, she moved from the flats to the top of Iron Mine Hill. A fattened female will draw in males quicker than flies on feces. Like a jack rabbit on a hot date, our male tiger, CT11, made a major move of over 300 meters to join her. And on the evening of 7 September, lucky Marty and John Slone found the pair in full coitus. See image 3. While we were blessed to see five pairings last year, this is the first mating event with tigers that we have ever witnessed. We’re moving on up!

I’ve tossed a hodge-podge of images into this report. They’re all labeled, so that you will know who is who and when. Look for a full screen view of a cluster of three barrel cacti. Where’s Waldo? The next image reveals him. Look for two images of a tortoise. The first shows the surreal backdrop of a Sonoran Desert, and the second pulls the rear of the tortoise into view. Look carefully at the rear vertebral scute. That is what is left of a license plate that was affixed to his shell in 2005. It took that rascal eight years to finally wear off. Nice job, Josh! Check out the nice string of rattles on CT14. This snake in particular is still in the game for another year, thanks to the 2600 club. He was on the bubble prior to your generosity. He is probably less grateful than we are about the prospect, but there is no allowance for poop socks on our turf. 

The second to the last image is a teaser for you. You won’t have to look too hard to see that there is more than one snake in that image. By June, despite assurances from Dr. DeNardo that CM10, “Susan,” had six neonates in her ovaries, we had determined that Susan was not pregnant. The night that this photo was taken, I was still under the notion that she was not pregnant. I was correct! It was not until 10 days after this image was taken that the two neonates were discovered.



























Everybody ought to carry a camera. They come in handy sometimes! Our next report will center on matters of fecundity in paradise. For now:

This here is Roger Repp, signing off from Southern Arizona, where the turtles are strong, the snakes are handsome, and the lizards are ALL above average. It is a place where every meal is a banquet, every sunrise is an event, and every sunset brings the promise of good things lying ahead. 


Thursday, September 12, 2013

Rhacophorid frog phylogeny on Borneo

Kurixalus appendiculatus
Rhacophoridae is a major clade of Afro-Asian tree frogs, that has radiated into many different niches. Rhacophorids contribute significantly to the high species richness and reproductive diversity of Sundaland vertebrates. Nonetheless, rhacophorid evolution, especially on Borneo, has not been studied within a phylogenetic context. In a new study Hertwig et al. examine the phylogenetic relationships of 38 (of 41 known) Bornean  rhacophorid frogs, in combination with data from previous phylogenetic studies. In the final super matrix of 91 species, they analyse sequence data from two mitochondrial and three nuclear genes. The results show the genus Rhacophorus as a paraphyletic  assemblage. Consequently they transfer Rhacophorus appendiculatus and R. kajau to two other genera and propose the new phylogeny-based combinations- Kurixalus appendiculatus and Feihyla kajau, respectively. Surprisingly they also found Theloderma moloch, a northeast Indian species, is an independent lineage of frogs within the  rhacphorid clade, separate from the other species of Theloderma (asperum, corticale, and rhododiscus) in the study. They also use their phylogenetic hypotheses to reconstruct the evolution of reproductive modes in rhacophorid tree frogs. Direct development to the exclusion of a free larval stage evolved twice independently, once in an ancestor of the Pseudophilautus + Raorchestes clade in India and Sri Lanka, and once within Philautus in Southeast Asia. The deposition of egg clutches covered by a layer of jelly in Feihyla is also present in F. kajau and thus confirms its generic reassignment. The remarkably high diversity of rhacophorid tree frogs on Borneo is the outcome of a complex pattern of repeated vicariance and dispersal events caused by past changes in the climatic and geological history of the Sunda shelf. The authors also identified geographic clades of closely related endemic species within Rhacophorus and Philautus, which result from local island radiations on Borneo.

Citation
Hertwig ST,  Schweizer M, Das I, Haas A. 2013. Diversification in a biodiversity hotspot – The evolution of Southeast Asian rhacophorid tree frogs on Borneo (Amphibia: Anura: Rhacophoridae). Molecular Phylogenetics and Evolution 68: 567–581.

Tuesday, September 3, 2013

The record-sized alligator


The major news outlets are carrying the story of Dustin Brockman of Vicksburg, Mississippi who, with his brother and friend, killed a 727-pound record breaking alligator that was 13 feet, 4.5 inches long. The previous weight record was 697.5 pounds, according to a Mississippi Department of Wildlife, Fisheries, program coordinator.

Brockman is quoted as saying, “We chased him for about two hours, ...Then we got a shot on him.” The alligator was shot with a crossbow before they could shoot it with a shotgun. It took four hours to get the gator into the boat, it was too heavy for the three men to handle so they just waited in the middle of the river for the sun to rise. At 6:30 (a.m.) Brockman called three or four more guys to help load the alligator into the boat.

Just an hour prior to the Brockman catch, another hunting party led by Beth Trammell of Madison, Mississippi hooked a 13-foot, 5.5-inch alligator near Redwood. The Trammell party's alligator broke the previous weight record with their 723.5-pound catch until Brockman broke it 60 minutes later.

According to the media the current length record  has yet to be broken, is 13 feet, 6.5 inches. That alligator was captured on the Pascagoula River in 2008, according to the Mississippi Wildlife, Fisheries and Parks department.

Now, these are certain large animals. But neither qualifies as the record size alligator. In fact, neither iseven close to being the record sized alligator. Edward Avery Mc lLHenny's 1935 book, The Alligator's Life History is a natural history classic. Mc lLHenny's  describes the alligator's voice, hibernation habits, den construction, feeding habits, reproduction, growth, predation and other aspects of alligator life history in great detail.  All of which has been subsequently verified by 20th century crocodilian biologists. Mc lLHenny's  lived on Avery Island, Louisiana and became a prominent conservationist and wildlife advocate. 

On page 59 of his book, Mc lLHenny's  writes,


"There is plenty of evidence in the written record of long past observers that alligators in Louisiana attain an extreme length of, at least eighteen or twenty feet. To my certain knowledge, there has been taken in the vicinity of Avery island, three alligators exceeding eighteen feet in length. One of these was an alligator known to we boys as "Monsurat," killed by Mr. Robert Mooney at Avery Island in 1879, which was measured by my father. This alligator was eighteen feet, three inches in length. The next large one that I remember seeing measured, was killed by Robert Dell, our plantation overseer, in October, 1882, at the junction of the road across the marsh joining Avery Island with the mainland, at the Avery Island end. Dell was coming in over the road and saw this alligator crossing the road. He had a pistol with him, and shot the alligator from his horse, killing it. On his describing its size to my father and uncles, a four-mule team and wagon was sent to bring it to our house. This alligator measured eighteen feet, five and one-half inches."

He continues with a description of an alligator he killed and measured on January 2, 1890  in a small bayou that connected lake Cock with Vermilion Bay (LA). The animal measured 19 feet 2 inches. This is the record generally accepted by herpetologists for the largest Alligator mississippiensis.

Citation
MclLHenny, E. A. 1935. The Alligator's Life History.The Christopher Publishing House, Boston. 117 pp.




Thursday, August 29, 2013

Diet overlap in aquatic snake assemblages

Competition for prey is thought to be important in structuring snake assemblages. However, given the secretive behavior and low detectability of many snake species, this generalization is based on a limited number of studies, most of which focus on a single study site. In a forthcoming paper in the Journal of Zoology Durso et al (2013) examined differences in diet composition, trophic niche overlap, site occupancy and detectability of five sympatric aquatic snake species [eastern mud snake, Farancia abacura; banded watersnake, Nerodia fasciata; Florida green water snakes, N. floridana; glossy crayfish snakes, Regina rigida; and black swamp snakes, Seminatrix pygaea] between two different habitat types in the southeastern US. They studies  permanent wetlands with fishes (n = 13) and isolated, often ephemeral wetlands without fishes (n = 10). More than 3700 prey items were collected from snakes and compared diet composition among snake species to examine niche breadth and overlap, correcting for relative availability of prey captured independently in the same wetlands. They also evaluated evidence for competitive exclusion by estimating the probability of co-occupancy for pairs of snake species in each habitat type using occupancy modeling. In wetlands with fishes, niche overlap was low, suggesting resource partitioning. Conversely, in wetlands without fishes, niche overlap was high, with most species feeding on larval or paedomorphic ambystomatid salamanders, but competitive exclusion did not occur. They suggest that high co-occupancy of aquatic snakes in wetlands without fishes, despite the apparent lack of resource partitioning, is due to a combination of seasonally high abundance of high quality amphibian prey, unique aspects of predator physiology and stochastic abiotic processes that prevent these systems from reaching equilibrium. The results demonstrate that snake diets can be highly context (e.g. habitat) specific.

Citation
Durso AM, Willson J D, & Winne CT. (2013)  Habitat influences diet overlap in aquatic snake assemblages. Journal of Zoology. DOI: 10.1111/jzo.12061

Social female copperheads found to be non-kin

Recent observations suggest snakes may be far more social than previously thought, including the ability to recognize and group with kin, and provide parental care (defense) for young. Inclusive fitness theory predicts that benefits of such groupings should be greater when groups are composed of related individuals. Although the ability required to recognize kin under this theory has been observed in a wide range of vertebrates, it has only recently been reported in snakes. Li et al. (2013) tested competing hypotheses for aggregation behavior in female neonate copperhead snakes, female aggregations are common in nature; male aggregations have not been observed.  They asked is (1) aggregation is mediated by genetic relatedness, or is (2) aggregation is mediated by familiarity, i.e. learned. The authors found no effect of learning on neonate aggregation. With regard to relatedness, contrary to  expectation they found  unrelated individuals tended to aggregate more than related individuals. The authors suggest that the lack of aggregation behavior in related individuals may be due to selection for dispersal and/or reduced effects of predation or disease.

Citation
Li M., Moeller JF,  Smith CF. (2013). Family and Friends: What Factors Influence Aggregation in Female Copperhead Snakes?. Lander University 9: 15-9: 27.

Monday, August 26, 2013

Eastern coral snake venom found to contain molecules from 15 toxin families

Snake venom is shaped by the ecology and evolution of the species that makes it. Evidence of positive selection in toxins have been consistently documented, reflecting the role of venoms as an ecologically critical phenotype. New World coral snakes (Elapidae) are represented by three genera and over 120 species and subspecies that are capable of causing significant human morbidity and mortality, yet coral-snake venom composition is poorly understood in comparison to that of Old World elapids.

In a recently published article Mark Margres of Florida State University and colleagues used high-throughput sequencing to identify thousands of loci, while providing characterizations of expression patterns and the molecular evolutionary forces acting within the venom gland.

The authors describe the de novo assembly and analysis of the venom-gland transcriptome of the eastern coral snake (Micrurus fulvius). The identified 1,950 nontoxin transcripts and 116 toxin transcripts. These transcripts accounted for 57.1% of the total reads, with toxins accounting for 45.8% of the total reads. Phospholipases A2 and three-finger toxins dominated expression, accounting for 86.0% of the toxin reads. A total of 15 toxin families were identified, revealing venom complexity previously unknown from New World coral snakes. Toxins exhibited high levels of heterozygosity relative to nontoxins, and overdominance may favor gene duplication leading to the fixation of advantageous alleles. Phospholipase A2 expression was uniformly distributed throughout the class while three-finger toxin expression was dominated by a handful of transcripts, and phylogenetic analyses indicate that toxin divergence may have occurred following speciation. Positive selection was detected in three of the four most diverse toxin classes, suggesting that venom diversification is driven by recurrent directional selection.

The new research describe the most complete characterization of an elapid venom gland to date. Toxin gene duplication may be driven by heterozygote advantage, as the frequency of polymorphic toxin loci was significantly higher than that of nontoxins. Diversification among toxins appeared to follow speciation reflecting species-specific adaptation, and this divergence may be directly related to dietary shifts and is suggestive of a co-evolutionary arms race.


Citation
Margres MJ, Aronow K, Loyacano J, Rokyta DR 2013.The venom-gland transcriptome of the eastern coral snake (Micrurus fulvius) reveals high venom complexity in the intragenomic evolution of venoms. BMC Genomics 2013, 14:531.

Saturday, August 17, 2013

Female mate choice in Hyla chrysoscelis

From frogs to humans, selecting a mate is complicated.  Females of many species judge suitors based on many indicators of health or parenting potential. But it can be difficult for males to produce multiple signals that demonstrate these qualities simultaneously.

In a study of gray tree frogs, a team of University of Minnesota researchers discovered that females prefer males whose calls reflect the ability to multitask effectively.  In this species (Hyla chrysoscelis) males produce "trilled" mating calls that consist of a string of pulses.

Typical calls can range in duration from 20-40 pulses per call and occur between 5-15 calls per minute. Males face a trade-off between call duration and call rate, but females preferred calls that are longer and more frequent, which is no simple task.

The findings were published in August issue of Animal Behavior.

"It’s kind of like singing and dancing at the same time," says Jessica Ward, a postdoctoral researcher who is lead author for the study. Ward works in the laboratory of Mark Bee, a professor in the College of Biological Sciences’ Department of Ecology, Evolution and Behavior.

The study supports the multitasking hypothesis, which suggests that females prefer males who can do two or more hard-to-do things at the same time because these are especially good quality males, Ward says.  The hypothesis, which explores how multiple signals produced by males influence female behavior, is a new area of interest in animal behavior research.

By listening to recordings of 1,000 calls, Ward and colleagues learned that males are indeed forced to trade off call duration and call rate. That is, males that produce relatively longer calls only do so at relatively slower rates.

"It's easy to imagine that we humans might also prefer multitasking partners, such as someone who can successfully earn a good income, cook dinner, manage the finances and get the kids to soccer practice on time."

The study was carried out in connection with Bee’s research goal, which is understanding how female frogs are able to distinguish individual mating calls from a large chorus of males. By comparison, humans, especially as we age, lose the ability to distinguish individual voices in a crowd. This phenomenon, called the "cocktail party" problem, is often the first sign of a diminishing ability to hear. Understanding how frogs hear could lead to improved hearing aids.

College of Biological Sciences faculty conduct research in all areas of biology, from molecules to ecosystems, which supports applications in medicine, renewable energy, agriculture and biotechnology. The college offers degree programs in biochemistry, molecular biology and biophysics; genetics, cell biology and development; ecology, evolution and (animal) behavior; plant biology; microbiology and neurosciences. Admission to undergraduate programs is highly competitive.

Citation
Ward JL, Love EK, Vélez A, Buerkle NP, O'Bryan LR, Bee MA. 2013. Multitasking males and multiplicative females: dynamic signalling and receiver preferences in Cope's grey treefrog. Animal Behaviour, 2013; 86(2):231 DOI: 10.1016/j.anbehav.2013.05.016

Thursday, August 15, 2013

Sea snakes disappear at Ashmore Reef despite protection


The Ashmore Reef National Nature Reserve was established in 1983 and covers 583 kmAshmore Reef  contains seagrass beds, intertidal sand flats, coral reef flats, and lagoons, and supports an important and diverse range of species, including 14 species of sea snakes, a population of dugong that may be genetically distinct, a diverse marine invertebrate fauna, and many endemic species, especially of sea snakes and molluscs. Feeding and nesting sites for loggerhead, hawksbill and green turtles are present. And, it is an Important Bird Area with 50,000 breeding pairs of seabirds.

Malcolm Smith recognized the high diversity and abundance of  sea snakes in his  1926 Monograph of Sea Snakes. In 1973  Alpha Helix expedition collected more than 350 sea snakes representing nine species in less than two weeks and observed many more In 2005 the  standing stock of sea snakes was estimated at about 40,000  snakes on the 174 kmreef flat of Ashmore Reef.

Besides high species diversity and abundance, there are high levels of sea snake endemism at Ashmore Reef. Half of the species (3/6) from the Aipysurus lineage recorded from Ashmore Reef are restricted to the Timor Sea. Endemics that almost certainly evolved in the Timor Sea highlighting the  role this region has played in the evolutionary history of the Aipysurus lineage. Additionally four of the nine resident species and three of the five vagrant species are Australasian endemics.

In a new study, Lukoschek et al. (2013) report on surveys conducted between 1973 and 2010. They recorded the highest abundances (average 42–46 snakes day)  and species richness (nine species) in 1973 and 1994. In 2002 abundance had declined by more than 50% (21 snakes day) and only five species were recorded. Since 2005 abundances have been consistently low (1–7 snakes per day) with just two species, Aipysurus laevis and Emydocephalus annulatus, recorded in significant numbers. Extensive searches since 2005 (especially in 2010) five species of sea snake historically abundant at Ashmore Reef have not been observed and are presumed  locally extinct. These species include three Timor Sea endemics Aipysurus apraefrontalis, Aipysurus foliosquama, Aipysurus fuscus, and one Australasian endemic Aipysurus duboisii. Declines in sea snake abundance and diversity at Ashmore Reef cannot be attributed to differences in survey methods over time.

The authors discuss habitat loss, illegal harvesting, decline in prey, disease, invasive species, and pollution as possible causes for the decline. But it is important to note the declines happened in spite of Ashmore Reef's National Nature Reserve (IUCN Category 1a) status that was declared in 1983 and, although the causes for the declines are not known, this protection has not prevented their disappearance.

Citation
Lukoschek V, Beger M, Ceccarelli  D,  Richards Z,  Pratchett M, 2013. Enigmatic declines of Australia’s sea snakes from a biodiversity hotspot, Biological Conservation, 166, 191-202, ISSN 0006-3207,

Tuesday, August 6, 2013

The beaded lizard reassed

The beaded lizard (Heloderma horridum) has a fragmented distribution in Mesoamerica that extends from northwestern Mexico to eastern Guatemala.  Locally known as the “escorpión” its natural history is surrounded by mystery, notoriety and misconception. Consequently, it is frequently slaughtered when encountered. Adding to this anthropogenic pressure, beaded lizard populations, with rare exceptions  occur primarily in seasonally dry tropical forests,  the most endangered biome in Mesoamerica owing to persistent deforestation for agriculture, cattle ranching, and a burgeoning human population. Drought and fires escalate the above threats and recent predictive models of climate change suggest  persistence of seasonally dry tropical forests in this region is highly dubious.

Despite its large size and charismatic nature, knowledge of the ecology, geographic distribution, and status of beaded lizard populations remains limited.

Reiserer et al. (2013) reassess the taxonomic status of the beaded lizard populations using morphology, biogeography, and a recent molecular-based analysis conducted by Douglas et al. (2010).

The authors found the greatest divergence between H. h. charlesbogerti and H. h. exasperatum (9.8%), and the least between H. h. alvarezi and H. h. charlesbogerti (1%). The former clade represents populations that are widely separated in distribution (eastern Guatemala vs. southern Sonora, Mexico), while  in the latter clade the populations are much closer (eastern Guatemala vs. Chiapas, Mexico). The nominate subspecies (Heloderma h. horridum) differed from the other subspecies of H. horridum by 5.4% to 7.1%.

The new study suggests beaded lizards diverged from a most-recent common ancestor about 35 million years ago in the Late Eocene, and subsequent diversification occurred during the late Miocene (9.71 mya), followed by a lengthy stasis of up to five million years, more recent diversification  extended into the Pliocene and Pleistocene. In both beaded lizards and seasonally dry tropical forests, the tempo of evolution and diversification was uneven, and their current distributions are fragmented. Based on multiple lines of evidence, including a review of the use of trinomials in taxonomy, the authors elevated the four subspecies of beaded lizards to full species: Heloderma alvarezi (Chiapan beaded lizard), H. charlesbogerti (Guatemalan beaded lizard), H. exasperatum (Río Fuerte beaded lizard), and H. horridum (Mexican beaded lizard), with no changes in their vernacular names. The full article is available on-online.

Citations
Reiserer RS, Schuett GW, Beck DD. 2013. Taxonomic reassessment and conservation status of the beaded lizard, Heloderma horridum (Squamata: Helodermatidae). Amphibian & Reptile Conservation 7(1): 74–96.

Douglas ME, Douglas MR, Schuett GW, Beck DD, Sullivan BK. 2010. Conservation phylogenetics of helodermatid lizards using multiple molecular markers and a supertree approach. Molecular Phylogenetics and Evolution 55: 153–167.

Friday, August 2, 2013

A second specimen of the bush viper, Atheris hirsuta

 Atheris hirsuta
The viper, Atheris hirsuta was described by Ernst & Rödel in  2002, based on a single specimen found near the ecological research station in the Taï National Park, Côte d’Ivoire. The holotype was found in secondary rainforest between a field station and the town of Taï. It was collected on a dirt road during heavy rain, however, it is clearly adapted to an arboreal lifestyle.

Recently a short survey of the herpetofauna of Mt. Swa in Nimba County, Liberia (~200 km west of the type locality) revealed a second specimen of this species. The mountain does harbour good secondary forests and altitude stays below 600 m above seal level. The specimen was found around 2100 h on the 26 September 2012. The individual was observed climbing in secondary vegetation about 2 m above ground on the ridge of the mountain at about 585 m. No water bodies of any kind were found on top of the ridge. Weather was windy, cloudy but without rain.

Tai National Park holds the largest protected rainforest in West Africa. The forest habitat outside the national park is fragmented and being degraded by agricultural and human population expansion. Eventually  these pressures are expected to extend into the national park.

Citation
Penner J,  Gonwouo NL &  Rodel M-O1 2013. Second record of the West African hairy bush viper
Atheris hirsuta Ernst & Rödel, 2002 (Serpentes: Viperidae). Zootaxa 3694 (2): 196–200.