Sunday, January 15, 2017

Low cost method for surveying Eastern Massasauga Rattlesnake

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

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

Saturday, January 14, 2017

An introduced snake on Ibiza Island, the Horseshoe Whip Snake

Hemorrhois hippocrepis Photo credit: Accipiter (R. Altenkamp)
Island ecosystems may be more vulnerable to invasive species than any other ecosystems. Island species have often evolved in isolation with reduced competition and predation from mainland species. When new species invade an island they are often able to out-compete the local endemics resulting in serious population declines or extinctions. The Mediterranean's Balearic Islands have been isolated from the continent for 5.33 million of years. Human-mediated introductions started by the end of the third millennium BCE, when humans colonized the islands and alien species introductions began. Two mammals, the European Pine Marten, Martes martes, and the Least Weasel, Mustela nivalis, together with an introduced snake, False Smooth Snake, Macroprotodon cucullatus, have been considered responsible for the extinction of the native lizard Podarcis lilfordi on the main islands.
Podarcis pityusensis Wikimedia Commons

Until quite recently, all except two of the larger 63 Mediterranean islands larger than 75 km2 harbored at least one snake species. The exception were the westernmost Balearic islands, also known as the Pityusic islands, Ibiza, and Formentera, which were never colonized by snakes. This absence of snakes was recognized by Pliny the Elder two thousand years ago. Between 12 and 13 years ago, three species of snakes (Horseshoe Whip Snake, Hemorrhois hippocrepis; Ladder Snake, Rhinechis scalaris; and the Montpellier snake, Malpolon monspessulanus) were introduced in Ibiza when old ornamental olive trees were imported from the southern Iberian Peninsula. However, there have not been any records of the Montpellier snake in Ibiza during the last six years. The Ladder Snake has been captured infrequently which might mean that it is struggling to establish a population. The Horseshoe Whip Snake, however, is expanding in Ibiza. It is a large, slender-bodied, long-tailed colubrid distributed throughout the Western Mediterranean. It was first reported on Ibiza in 2003.

In a new paper Hinkey et al. (2017) report that specimens of the Horseshoe Whip Snake obtained from an early eradication campaign showed a rapid expression of phenotypic plasticity and acquired larger body sizes than those of the source population. This was probably due to a high prey availability and few snake predators. the Horseshoe Whip Snake is thriving at the expense of a small variety of native and non-native prey. However, the predation pressure on the endemic Ibiza wall lizard, Podarcis pityusensis, the only native reptile on the island, is very high.  The Ibiza Wall Lizard represents 56% of the prey taken by the Horseshoe Whip Snake and the heavy predation may threaten its survival.

The authors conclude the Horseshoe Whip Snake threatens the biodiversity of Ibiza and that the threat may extend to smaller populations of lizards on  surrounding islands. The snake has been observed swimming in the sea and a shed skin was found on one islet. It seems that an eradication effort is needed.

Citation
Hinckley A, Montes E, Ayllón E, Pleguezuelos JM. 2017. The fall of a symbol? A high predation rate by the introduced horseshoe whip snake Hemorrhois hippocrepis paints a bleak future for the endemic Ibiza wall lizard Podarcis pityusensis. European Journal of Wildlife Research. 63(1):13.

Friday, January 13, 2017

Rattlesnakes strike faster in the wild — compared to laboratory observations

Biologists from the University of California at Riverside used high-speed cameras to study predator-prey interactions in the wild. They found that the rattlesnakes strike faster in the wild — compared to laboratory observations conducted in prior studies — but the kangaroo rats' "sling shot" tendons give them a good chance at evasion.


Feeding is paramount to the survival of almost every animal, and just about every living organism is eaten by another. Not surprisingly, the animal kingdom shows many examples of extreme specialization -- the chameleon's tongue, fox diving into snow, cheetah sprinting -- for capturing prey or escaping predators.

The antagonistic predator-prey relationship is of interest to evolutionary biologists because it often leads to extreme adaptations in both the predator and prey. One such relationship is seen in the rattlesnake-kangaroo rat system -- a model system for studying the dynamics of high-power predator-prey interactions that can be observed under completely natural conditions.

Curiously, however, very little is known about the strike performance of rattlesnakes under natural conditions. But that is now about to change because technological advances in portable high-speed cameras have made it possible for biologists like Timothy Higham at the University of California, Riverside to capture three-dimensional video in the field of a rattlesnake preying on a kangaroo rat.

"Predator-prey interactions are naturally variable -- much more so than we would ever observe in a controlled laboratory setting," said Higham, an associate professor of biology, who led the research project. "Technology is now allowing us to understand what defines successful capture and evasion under natural conditions. It is under these conditions in which the predator and prey evolve. It's therefore absolutely critical to observe animals in their natural habitat before making too many conclusions from laboratory studies alone."

A question Higham and his team are exploring in predator-prey relationships is: What factors determine the success/failure of a strike or escape? In the case of the rattlesnake and kangaroo rat, the outcome, they note, appears to depend on both the snake's accuracy and the ability of the kangaroo rat to detect and evade the viper before being struck.

"We obtained some incredible footage of Mohave rattlesnakes striking in the middle of the night, under infrared lighting, in New Mexico during the summer of 2015," Higham said. "The results are quite interesting in that strikes are very rapid and highly variable. The snakes also appear to miss quite dramatically -- either because the snake simply misses or the kangaroo rat moves out of the way in time."

Many studies have examined snake strikes, but the new work is the first study to quantify strikes using high-speed video (500 frames per second) in the wild.


In the paper, Higham and his coauthors conclude that rattlesnakes in nature can greatly exceed the defensive strike speeds and accelerations observed in the lab. Their results also suggest that kangaroo rats might amplify their power when under attack by rattlesnakes via "elastic energy storage."

"Elastic energy storage is when the muscle stretches a tendon and then relaxes, allowing the tendon to recoil like an elastic band being released from the stretched position," Higham explained. "It's equivalent to a sling shot -- you can pull the sling shot slowly and it can be released very quickly. The kangaroo rat is likely using the tendons in its lower leg -- similar to our Achilles tendon -- to store energy and release it quickly, allowing it to jump quickly and evade the strike."

To collect data, the team radio-tracked rattlesnakes by implanting transmitters. Once the rattlesnake was in striking position, the team carried the filming equipment to the location of the rattlesnake (in the middle of the night) and set up the cameras around the snake. The team then waited (sometimes all night) for a kangaroo rat to come by for the snake to strike.

"We would watch the live view through a laptop quite far away and trigger the cameras when a strike occurred," Higham said.

Next, the researchers plan to expand the current work to other species of rattlesnake and kangaroo rat to explore the differences among species.
Citation
 Higham TE, Clark RW, Collins CE, Whitford MD, Freymiller GA. 2017. Rattlesnakes are extremely fast and variable when striking at kangaroo rats in nature: Three-dimensional high-speed kinematics at night. Scientific Reports, 2017; 7: 40412 DOI: 10.1038/srep40412

Tuesday, January 3, 2017

Rhynchocalamus a poorly known clade of snakes from southwest Asia

The colubrid snake genus Rhynchocalamus composed of three small, gracile snakes distributed in Southwest Asia. While, these snakes are sometimes called Kikuri snakes, a name sometimes applied to the members of the genus Oligodon, they also tend to have blackheads and are sometimes called the blackheaded snakes, a name that may confuse them with the North American genus Tantilla. Their secretive fossorial lifestyle has resulted in them being poorly known and under studied. Only recently Šmíd et al. (2015) found Rhynchocalamus to be a member of the the Western Palearctic clade of Colubrinae and the sister to the awl-headed snakes of the genus  Lytorhynchus.

Three species of Rhynchocalamus are currently recognized, R. satunini (Turkey eastwards to Iran), R. arabicus (Yemen and Oman), and R. melanocephalus (from the Sinai Peninsula northwards to Turkey). Tamar et al. (2016) recently completed a comprehensive study on all known Rhynchocalamus species in order to review the intra-generic phylogenetic relationships and historical biogeography of the genus and describe a fourth species from Israel.

The molecular results found Rhynchocalamus monophyletic, and last shared an ancestor with Lytorhynchus in Late Oligocene. The three recognized species of Rhynchocalamus comprise four independently lineages with the genus diverge during the Middle Miocene. They discovered R. melanocephalus is paraphyletic. A population from the Negev Mountain area in southern Israel is phylogenetically closer to R. arabicus from Oman than to the northern populations of the species from Israel, Syria and Turkey and they describe this population as the new species Rhynchocalamus dayanae.

A) R. dayanae sp. nov. specimen from  Mitzpe Ramon, Negev Mountain, Israel; photo by Simon Jamison); (B) R. melanocephalus (Tartus, Syria; photo by Bayram Göçmen); (C) R. satunini (Artuklu, Mardin province, Turkey; photo by Bayram Göçmen); (D) R. arabicus (Wadi Ayoun, Dhofar Governorate, Oman; photo by Gabriel Martínez).

Citations

Šmíd, J;  Martínez G, Gebhart J, Aznar J,  Gállego J, Göçmen B, De Pous P, Tamar K & Carran-za S. 2015. Phylogeny of the genus Rhynchocalamus (Reptilia; Colubridae) with a first record from the Sultanate of Oman Zootaxa 4033 (3): 380–392.

Tamar K, Šmíd J, Göçmen B, Meiri S, Carranza S. (2016) An integrative systematic revision and biogeography of Rhynchocalamus snakes (Reptilia, Colubridae) with a description of a new species from Israel. PeerJ 4:e2769 https://doi.org/10.7717/peerj.2769.

Friday, December 30, 2016

Four new vipers were described in 2016

Bale Mountains Adder, Bitis harenna Gower et al. 2016
Bale Mountains Adder, Bitis harenna

Bale Mountains Adder is similar in scalation to Bitis parviocula. It is known from the holotype and one photograph taken of a specimen that was not collected. It inhabits the Bale Mountains of Ethiopia near the town of Dodola, which is on the main route between the Rift Valley and the chief settlements of the Bale Mountains region. Dodola lies on a heavily farmed plateau, and there is very little tree cover in the immediate vicinity of the town. The holotype is 665 mm long.

Talamancan palm-pitviper, Bothriechis nubestris Doan et al. 2016

The new species is a small to medium sized pitviper, 61 cm on average.It inhabits a small area in the northern Talamancan Cordillera of Costa Rica. The pit viper is a striking green-and-black, a coloration it shares with its close relative, the black-speckled palm-pitviper (Bothriechis nigroviridis). The two species look so similar that the Talamancan palm-pitviper
Talamancan palm-pitviperBothriechis nubestris 
went unrecognized for more than a century. 


Ilha dos Franceses LanceheadBothrops sazimai Barbo et al. 2016
This is a new insular species of  Bothrops from Ilha dos Franceses, a small island off the coast of Espírito Santo State, southeastern Brazil. The new species differs from mainland populations of B. jararaca in its small size, relative longer tail, relative smaller head length, and relative larger eyes. Like other island Bothrops,  Bothrops sazimai reaches high population densities, is nocturnal, semi- arboreal, and feeding on small lizards and centipedes. Due its unique and restricted area of occurrence, declining quality of habitat, and constant use of the island for tourism, the new species may be considered as critically endangered.
Ilha dos Franceses LanceheadBothrops sazimai


Walser Viper, Vipera walser Ghielmi et al. 2016 
Vipera walser is a new viper from the northwestern Italian Alps. Despite its overall morphological resemblance with Vipera berus, the new species is genetically distinct  from both V. berus and other vipers occurring in western Europe. Morphologically, the new species appear to be more similar to V. berus than to its closest genetic relatives occurring in the Caucasus The extant population shows a very low genetic variability based upon mitochondrial markers, suggesting that the taxon has suffered a serious population reduction or bottleneck in the past. The species is extremely range-restricted (inhabiting less than 500 km2) and occurs at in two disjunct sites within the high rainfall valleys of the Alps
Walser Viper, Vipera walser 
north of Biella. This new species should be classified as globally ‘endangered’ due to its small and fragmented range, and an inferred population decline. The near-future threats to the species are habitat changes associated with reduced grazing, along with human persecution, and collecting.


Citations

Barbo FE, Gasparini JL, Almeida AP, Zaher H, Grazziotin FG, Gusmão RB, Ferrarini JM, Sawaya RJ. 2016. Another new and threatened species of lancehead genus Bothrops (Serpentes, Viperidae) from Ilha dos Franceses, Southeastern Brazil. Zootaxa. 4097(4):511-29.

Doan TM, Mason AJ, Castoe TA, Sasa M, Parkinson CL. 2016. A cryptic palm-pitviper species (Squamata: Viperidae: Bothriechis) from the Costa Rican highlands, with notes on the variation within B. nigroviridis. Zootaxa.  4138(2):271-90.

Ghielmi S, Menegon M, Marsden SJ, Laddaga L, Ursenbacher S. 2016. A new vertebrate for Europe: the discovery of a range‐restricted relict viper in the western Italian Alps. Journal of Zoological Systematics and Evolutionary Research 54(3):161-73.

Gower DJ, Wade EO, Spawls S, Bohme W, Buechley ER, Sykes D, Colston TJ. 2016. A new large species of Bitis Gray, 1842 (Serpentes: Viperidae) from the Bale Mountains of Ethiopia. Zootaxa. 4093(1):41-63.

Thursday, December 29, 2016

Twelve new species of Anolis were described in 2016.

Anolis is the largest genus of lizards with more than 416 described species. Eight new species
were described by Kohler and Hedges (2016) 
Anolis chlorodius, Hispaniola
revising the green anoles of Hispaniola. Using morphological and molecular genetic data the authors recognize 16 species of green anoles on the island, eight of which they describe as new species (A. apletolepis, A. chlorodius, A. divius, A. eladioi, A. gonavensis, A. leucodera, A. prasinorius, and A. viridius). Three other species were raised from subspecific to species level (A. cyanostictus, A. demissus and A. pecuarius) and one was resurrected from synonymy with A. chlorocyanus (A. peynadoi).

Another new anole from Hispaniola, Anolis landestoyi, was described by Mahler et al. (2016). The new species, named Anolis landestoyi, was found in the Dominican 
Anolis landestoyi, Hispaniola
Republic but bears a strong resemblance to Cuba’s Chamaeleolis anoles.  Chamaeleolis anoles look less like typical anoles and more like chameleons: large, cryptic, slow-moving, and prone to clinging to lichen-covered branches high in forest canopies. Anolis landestoyi is restricted to a unique habitat only found in a small area in the western Dominican Republic that is rapidly disappearing due to illegal deforestation.

Two new anoles from Mexico were described by Köhler et al. (2016). Anolis (Norops) mccraniei occurs at elevations of 200–1,740 m throughout much of Honduras (except for the Atlantic slopes of the Cordillera Nombre de Dios
 in northern Honduras), as well as in extreme 
Anolis purpuronectes, Oaxaca, Mexico
northwestern El Salvador, northern Nicaragua, and eastern Guatemala. Anolis (Norops) wilsoni is restricted to the Atlantic slopes of the Cordillera Nombre de Dios in the departments of Atlántida and Colón in northern Honduras, at elevations from near sea level to 980 m.

The semi-aquatic Anolis purpuronectes was described by Gray, et al. 2016 from the western portion of the Chimalapas region in extreme northeastern Oaxaca and adjacent southeastern Veracruz, Mexico. They found this lizard sleeping on low vegetation within one metre of a stream, on boulders or logs in or along streams; on boulders, logs, or wet leaf litter; or within boulder crevices near small waterfalls. The type locality is a corridor of closed-canopy forest surrounded by highly disturbed areas.

Citations

Gray L, Meza-Lázaro R, Poe S, de Oca AN. A new species of semiaquatic Anolis (Squamata: Dactyloidae) from Oaxaca and Veracruz, Mexico. 2016. The Herpetological Journal. 26(4):253-62.

Köhler G, Hedges SB. 2016. A revision of the green anoles of Hispaniola with description of eight new species (Reptilia, Squamata, Dactyloidae). Novitates Caribaea 9: 1-135. E-print

Köhler G, Townsend JH, Petersen CB. 2016. A taxonomic revision of the Norops tropidonotus complex (Squamata, Dactyloidae), with the resurrection of N. spilorhipis (Álvarez del Toro and Smith, 1956) and the description of two new species. Mesoamerican Herpetology. 3:8-41.

Mahler DL, Lambert SM, Geneva AJ, Ng J, Hedges SB, Losos JB, Glor RE. 2016.  Discovery of a Giant Chameleon-Like Lizard (Anolis) on Hispaniola and Its Significance to Understanding Replicated Adaptive Radiations. The American Naturalist. 188(3):357-64.


Three new turtles described in 2016

Three new species of turtles were described during 2016. This brings the number of recognized species to 345. All three of the new species have relatively small distributions and are good candidates for threatened status.

The Yellow-bellied Snapping Turtle, Elseya flaviventralis

Goode's Thornscrub Tortoise, Gopherus evgoodei

The Yellow-bellied Snapping Turtle, Elseya flaviventralis Thomson & Georges, 2016 (family Chelidae), inhabits the Mary, South Alligator, East Alligator, Goyder and Mann River drainages of the northeastern portion of the Northern Territory (Arnhem Land region), Australia.

Goode's Thornscrub Tortoise, Gopherus evgoodei Edwards, Karl, Vaughn, Rosen, Meléndez-Torres & Murphy, 2016 (family Testudinidae). The new tortoise is a habitat specialist and is found exclusively in thornscrub and tropical broadleaf forests that comprise about 24,000 km2.

Isan Snail-eating Turtle, Malayemys isan Sumontha, Brophy, Kunya, Wiboonatthapol & Pauwels, 2016 (family Geoemydidae). This species inhabits northeastern Thailand, where it uses shallow, stagnant or slow-moving freshwater.

Isan Snail-eating Turtle, Malayemys isa

Citations

Brophy, Timothy R.; Sumontha, M.; Kunya, K.; Wiboonatthapol, S.; and Pauwels, O.S.G., 2016. A New Snail-Eating Turtle of the Genus Malayemys Lindholm, 1931 (Geoemydidae) from Thailand and Laos. Faculty Publications and Presentations. Paper 120. http://digitalcommons.liberty.edu/bio_chem_fac_pubs/120.

Edwards T, Karl AE, Vaughn M, Rosen PC, Torres CM, Murphy RW (2016) The desert tortoise trichotomy: Mexico hosts a third, new sister-species of tortoise in the Gopherus morafkaiG. agassizii group. ZooKeys 562: 131-158. https://doi.org/10.3897/zookeys.562.6124


Thomson S,  Georges A. 2016. A new species of freshwater turtle of the genus Elseya (Testudinata: Pleurodira: Chelidae) from the Northern Territory of Australia. Zootaxa 4061(1):18-28

Sunday, December 18, 2016

Northern Leopard Frog populations in the southwest

Rana pipiens. JCM
In the southwest, the Northern Leopard Frog, Rana (Lithobates) pipiens, is considered a threatened species, Much of this is due to droughts, land development, and falling water tables because of human water needs.

Invasive species are a major contributor to loss of biodiversity. However, translocations of a species within its own distribution are less frequently recognized, but have the potential for negative impacts on the native population. Genetic mixing may lead to loss of local adaptations or further decline through outbreeding depression. Cryptic invasions of new genetic material into populations that did not previously contain that genetic material may be quite difficult to recognize, but genetic tools can be used to recognize and monitor such intraspecific introductions. Conversely, translocations within species can be an important conservation tool to reduce inbreeding depression and replace lost genetic diversity.

Thus, cryptic invasions can be either an aid or a hinder conservation efforts. In a recent paper O'Donnell et al.(2016) tested for the presence of non-native genotypes and assessed the extent and nature of introgression in populations of Northern Leopard Frog in the southwestern US, where populations have declined to a few remnant populations. The most abundant and diverse complex of populations in the region contained a mitochondrial haplotype that was not native to the western US. This haplotype is likely the  resulting of released pets, laboratory animals, or animals accidentally release during fish stocking. These non-native haplotypes were well integrated into a large complex of ponds and lakes, contributing to high genetic diversity in this area. The geographic extent of non-native genetic influence within this population makes eliminating or controlling the non-native component of this population not possible.

The authors recommend assessing the progress and fate of the introgression over time—along with population fitness parameters—to determine whether this introduction is beneficial or detrimental to population persistence. Meanwhile, translocations from nearby locations with similar environmental conditions have the best prospects for avoiding problems with outbreeding depression in other declining populations and will also most effectively preserve regional genetic diversity.

Citation
O’Donnell RP, Drost CA, Mock KE. Cryptic invasion of Northern Leopard Frogs (Rana pipiens) across phylogeographic boundaries and a dilemma for conservation of a declining amphibian. Biological Invasions 2016:1-4.

Saturday, December 17, 2016

A new Tantilla from the dry forests of Peru

A male Tantilla tjiasmantoi Koch & Veneagas, 2016.
Seasonally dry tropical forests have a distinct seasonality with several months of arid-like conditions when many plants lose their leaves. In South America, these forests are discontinuous and can occupy large areas such as the Caatinga in northeastern Brazil or small fragments as being found in inter-Andean valleys of Peru or Ecuador. The species compositions differ substantially from one seasonally dry forest to another. The Equatorial dry forest stretches from southern Ecuador to the northern part of Peru  where it extends southward in two small stripes. One stripe continues along the west coast of the Andes, the other penetrates the valley of the Marañón River and its tributaries. Sixty-one species are currently recognized within the genus Tantilla. Twelve species occur in mainland South America, of which only two are found in Peru: T. capistrata and T. melanocephala. Most Tantilla have a uniformly colored or a longitudinally striped dorsal color pattern. Only T. shawi Taylor, from Mexico, T. semicincta  from Colombia and Venezuela, and T. supracincta from Colombia, Costa Rica, Ecuador, Nicaragua, and Panama have a transverse-banded color pattern on the dorsal part of the body. Koch and Venegas (2016) describe a new Tantilla from the dry forest of the northern Peruvian Andes based on two specimens, which exhibit a conspicuous sexual dimorphism. Tantilla tjiasmantoi sp. nov. represents the third species of the genus in Peru and one with an unusual transverse-banded pattern. A detailed description of the skull morphology of the new species is given based on micro-computed tomography images. The habitat of this new species is seriously threatened due to human activity. Conservation efforts are urgently needed in the inter-Andean valley of the Maranon River.

Citation
Koch C, Venegas PJ. (2016) A large and unusually colored new snake species of the genus Tantilla (Squamata; Colubridae) from the Peruvian Andes. PeerJ 4:e2767 https://doi.org/10.7717/peerj.2767

Wednesday, December 14, 2016

The number of species of birds and what it says about the number of species of reptiles

This blog usually focuses on non-avian reptiles. However, the research reported here on birds has great implications for how we think about the number of species of reptiles. Birds are the most studied group of vertebrates, reptiles are much less studied. Thus if it is possible to double the number of bird species, the number of reptile species is much, much greater than any of the current estimates.

According the the Reptile Database between February 2008 and August 2016, the number of reptiles increased from 8734 to 10,450, in increase of 1716 species or 19.6%.  Just considering the years between 2010 and 2016 there have been 972 new species of reptiles described. While during that same period (2010 to 2016) only 51 species of birds were described. Thus it would seem that the number of species of reptiles particularly squamates (lizards and snakes) is dramatically higher than my estimate made in my 2011 post.

In time of climate change, habitat destruction, pollution, and other forms of environmental degradation are occurring more rapidly than in previous history - it is entirely possible that many species are becoming extinct before they have been described.
The above map was published in 2012 by Saving Species.The variety of life on Earth is not spread evenly, but is concentrated in very special places. Above the world map is color coded for density of vertebrate species. Colors indicate the highest concentrations of the number of animal species across the world's land masses. Deep reds and yellows cover much of the tropics, indicating a huge number of species. The world’s high latitudes and its deserts are blue, indicating relatively low vertebrate diversity. 
New research led by the American Museum of Natural History suggests that there are about 18,000 bird species in the world -- nearly twice as many as previously thought. The work focuses on "hidden" avian diversity -- birds that look similar to one another, or were thought to interbreed, but are actually different species. Recently published in the journal PLOS ONE, the study has serious implications for conservation practices.

"We are proposing a major change to how we count diversity," said Joel Cracraft, an author of the study and a curator in the American Museum of Natural History's Department of Ornithology. "This new number says that we haven't been counting and conserving species in the ways we want."

Birds are traditionally thought of as a well-studied group, with more than 95 percent of their global species diversity estimated to have been described. Most checklists used by bird watchers as well as by scientists say that there are roughly between 9,000 and 10,000 species of birds. But those numbers are based on what's known as the "biological species concept," which defines species in terms of what animals can breed together.

"It's really an outdated point of view, and it's a concept that is hardly used in taxonomy outside of birds," said lead author George Barrowclough, an associate curator in the Museum's Department of Ornithology.

For the new work, Cracraft, Barrowclough, and their colleagues at the University of Nebraska, Lincoln, and the University of Washington examined a random sample of 200 bird species through the lens of morphology -- the study of the physical characteristics like plumage pattern and color, which can be used to highlight birds with separate evolutionary histories. This method turned up, on average, nearly two different species for each of the 200 birds studied. This suggests that bird biodiversity is severely underestimated, and is likely closer to 18,000 species worldwide.

The researchers also surveyed existing genetic studies of birds, which revealed that there could be upwards of 20,000 species. But because the birds in this body of work were not selected randomly -- and, in fact, many were likely chosen for study because they were already thought to have interesting genetic variation -- this could be an overestimate. The authors argue that future taxonomy efforts in ornithology should be based on both methods.

"It was not our intent to propose new names for each of the more than 600 new species we identified in the research sample," Cracraft said. "However, our study provides a glimpse of what a future taxonomy should encompass."

Increasing the number of species has implications for preserving biodiversity and other conservation efforts.

"We have decided societally that the target for conservation is the species," said Robert Zink, a co-author of the study and a biologist at the University of Nebraska, Lincoln. "So it follows then that we really need to be clear about what a species is, how many there are, and where they're found."

Citation
Barrowclough GF, Cracraft J, Klicka J, Zink RM. 2016 How Many Kinds of Birds Are There and Why Does It Matter? PLOS ONE, 2016; 11 (11): e0166307 DOI: 10.1371/journal.pone.0166307

Saturday, December 10, 2016

Two critically endangered sea snakes Aipysurus foliosquama and Aipysurus apraefrontalis

This is a photograph of the rare
short nosed sea snake discovered
on Ningaloo reef, Western Australia.
Photo credit: Grant Griffin, W.A.
Dept. Parks and Wildlife
Scientists from James Cook University have discovered two critically endangered species of sea snakes, previously thought to be extinct, off the coast of Western Australia.

It's the first time the snakes have been spotted alive and healthy since disappearing from their only known habitat on Ashmore Reef in the Timor Sea more than fifteen years ago.

"This discovery is really exciting, we get another chance to protect these two endemic Western Australian sea snake species," says study lead author Blanche D'Anastasi from the ARC Centre of Excellence for Coral Reef Studies at JCU.

"But in order to succeed in protecting them, we will need to monitor populations as well as undertake research into understanding their biology and the threats they face."

The discovery of the critically endangered short nose sea snake was confirmed after a Western Australia Parks and Wildlife Officer, Grant Griffin, sent a photo of a pair of snakes taken on Ningaloo Reef to Ms D'Anastasi for identification.

"We were blown away, these potentially extinct snakes were there in plain sight, living on one of Australia's natural icons, Ningaloo Reef," says Ms D'Anastasi.

"What is even more exciting is that they were courting, suggesting that they are members of a breeding population."

The researchers also made another unexpected discovery, uncovering a significant population of the rare leaf scaled sea snake in the lush seagrass beds of Shark Bay.

The discovery was made 1700 kilometres south of the snakes only known habitat on Ashmore Reef.

"We had thought that this species of sea snake was only found on tropical coral reefs. Finding them in seagrass beds at Shark Bay was a real surprise," says Ms D'Anastasi.

Both leaf scaled and short nosed sea snakes are listed as Critically Endangered under Australia's threatened species legislation, which means they have special protection. Despite the good news of the find, sea snake numbers have been declining in several marine parks, and scientists are at a loss to explain why.

"Many of the snakes in this study were collected from prawn trawl by-catch surveys, indicating that these species are vulnerable to trawling," says Dr Vimoksalehi Lukoschek from the Centre of Excellence for Coral Reef Studies.

"But the disappearance of sea snakes from Ashmore Reef, could not be attributed to trawling and remains unexplained.

"Clearly we need to identify the key threats to their survival in order to implement effective conservation strategies if we are going to protect these newly discovered coastal populations," Dr Lukoschek says.

The most common threat to sea snakes is usually thought to be incidental by-catch from trawling, and indeed, both species were sampled in trawl surveys in Shark Bay and Exmouth Gulf, suggesting that this is indeed a threat. However, trawling does not occur at the Timor Sea reefs because the reefs descend sharply into very deep waters. Thus the declines of these species could not be attributed to trawling. Trawling may be impacting coastal populations of these species. Other potential impacts on sea snakes include loss of habitats and/or prey, disease and recruitment failure due to coastal development, mining exploration and extraction, and climate change. However, until we identify the causes of previous extirpations of Aipysurus group species, it will be challenging to implement effective conservation strategies. Thus, in addition to the need for further field surveys to accurately document the true range extents and population  sizes of species (in coastal Western Australia and elsewhere), it also is critically important that targeted research be conducted to further our understanding of the biology and ecology of sea snakes, and address knowledge gaps about the key threatening processes.

Citation
B.R. D'Anastasi, L. van Herwerden, J.A. Hobbs, C.A. Simpfendorfer, V. Lukoschek. New range and habitat records for threatened Australian sea snakes raise challenges for conservation. Biological Conservation, 2016; 194: 66 DOI: 10.1016/j.biocon.2015.11.032

The human visual system has evolved specifically to detect snakes

Examples of a Random Image Structure Evolution (RISE) sequence for 
snake pictures. Participants looked at a sequence of 20 pictures with 
interpolation ration starting from 95% to 0% with steps of 5%. RISE
 sequence gradually changes from unorganized to well discernible. 
Photo credit: Nobuyuki Kawai

A Nagoya University research team uses new image processing tool to confirm human visual system has evolved specifically to detect snakes.

Some studies have suggested that the visual systems of humans and other primates are finely tuned to identify dangerous creatures such as snakes and spiders. This is understandable because, among our ancestors, those who were more able to see and avoid these animals would have been more likely to pass on their genes to the next generation. However, it has been difficult to compare the recognition of different animals in an unbiased way because of their different shapes, anatomical features, and levels of camouflage.

In a study reported recently in PLOS ONE, a pair of researchers at Nagoya University obtained strong support for the idea that humans have heightened visual awareness of snakes. The researchers applied an image manipulation tool and revealed that subjects could identify snakes in much more blurry images than they could identify other harmless animals in equivalent images.

The tool, called Random Image Structure Evolution (RISE), was used to create a series of 20 images of snakes, birds, cats, and fish, ranging from completely blurred to completely clear. The pair then asked subjects to views these images in order of increasing clarity until they could identify the animal in the picture.

"Because of the algorithm that it uses, RISE produces images that allow unbiased comparison between the recognition of different animals," first author Nobuyuki Kawai says. "In the images, the animals are 'camouflaged' in a uniform way, representing typical conditions in which animals are encountered in the wild."

The snakes were increasingly well-identified in the sixth to eighth of 20 images, while the subjects often needed to see the less blurred ninth or tenth images to identity the other animals. "This suggests that humans are primed to pick out snakes even in dense undergrowth, in a way that isn't activated for other animals that aren't a threat," co-author Hongshen He explains.

The findings confirm the Snake Detection Theory; namely, that the visual system of humans and primates has specifically evolved in a way that facilitates picking out of dangerous animals. This work augments understanding of the evolutionary pressures placed on our ancestors.

Citation
Nobuyuki Kawai, Hongshen He. Breaking Snake Camouflage: Humans Detect Snakes More Accurately than Other Animals under Less Discernible Visual Conditions. PLOS ONE, 2016; 11 (10): e0164342 DOI: 10.1371/journal.pone.0164342

Friday, December 9, 2016

The Frilled Lizard and its phylogeography

A typical defensive display of a Frilled Lizard.
The savanna-dwelling Australo-Papuan Frilled Lizards' spectacular threat display has made the lizard world famous. They are distributed across northern Australia and southern New Guinea. In a recent  Molecular Phylogenetics and Evolution article Pepper and colleagues (2017) examine the Frilled Lizard's phylogeography as it relates to changes in the savanna vegetation in the Plio/Pleistocene and the associated increase in aridity. The authors generated sequence data for one mitochondrial and four nuclear DNA loci (5052 base pairs) for 83 frilled lizards sampled throughout their range. They also quantified body proportion variation for 279 individuals. Phylogenetic analyses based on maximum likelihood and Bayesian species-tree methods resulted in three shallow clades that replace each other across the monsoon tropics. They found the expected pattern of male biased sexual size dimorphism in both maximum body size and head size but there was no sexual dimorphism in overall body shape or in frill size, relative to head size, supporting the hypothesis that the frill is used primarily as a threat display rather than a sexual display. The genetic clades are broadly consistent with known clinal variation in frill color that gradually shifts from west to east (red, orange, yellow/white) but otherwise show little morphological differentiation in body proportion measures. The biogeographic breaks between clades occur at the Carpentaria Gap and the lowlands surrounding the Ord River. Ecological niche modeling predicts where habitat suitability for Frilled Lizards in these regions. Extremely low intra-clade genetic diversity over vast geographic areas is indicative of recent gene flow that would likely have been facilitated by widespread savanna during interglacials, Or alternatively, may reflect population bottlenecks induced by extreme aridity during Pleistocene glacials. The shallow divergence between Australian and New Guinean samples is consistent with recent connections between Australia and New Guinea that would have been  via a savanna corridor across the Torres Strait. The authors do not support taxonomic recognition of any of the frilled lizard clades and consider C. kingii a single species with shallow phylogeographic structure and clinal variation in frill color.

Citation
Pepper M, Hamilton DG, Merkling T, Svedin N, Cser B, Catullo RA, Pryke SR, Keogh JS. Phylogeographic structure across one of the largest intact tropical savannahs: Molecular and morphological analysis of Australia’s iconic frilled lizard Chlamydosaurus kingii. 2017. Molecular Phylogenetics and Evolution. 106:217-27.

Thursday, December 8, 2016

Fossil Miocene amphibians and reptiles from Plakias, Crete


A modern alytid European frog, Bombina. JCM
The Neogene (the Miocene and Pliocene) extends from about 22.5 to 2.5 million years ago, and it has been termed "the age of snakes."  The global climate became seasonal, drier and cooler. Polar ice caps formed and thickened, and by the end of the Neogene the first of a series of glaciations of the current Ice Age began. Both the marine and continental flora and fauna contained modern looking species. Many older lineages of amphibians and reptiles had disappeared and were replaced by more modern lineages. Birds and mammals continued to dominant terrestrial vertebrate communities, and the first hominids, the ancestors of humans, evolved in Africa and dispersed into Eurasia. The Miocene composed the bulk of this time segment of Earth's history. In a new paper published in Geobios, Georgalis et al (2016) report on the fossil amphibian and reptiles from the late Miocene of Crete.

The excavation site was at Plakias (early Tortonian, MN 9), Crete, Greece. Most of the material recovered was fragmentary and precludes precise taxonomic assignment. However, the herpetofauna of Plakias was diverse and composed at least six different taxa: an alytid frog, a crocodilian, two turtles (a pan-trionychid and a geoemydid) and two squamates (an amphisbaenian and a colubroid snake). The crocodilian material represents the first such fossils described from Greece and furthermore, one of the latest occurrences of this group in Europe. The pan-trionychid and the geoemydid represent the oldest occurrences of these groups in Greece and further add to their scarce Miocene record from this country. The first description of a fossil amphisbaenian from Greece is also provided. The new specimens from Plakias add to our knowledge of the Miocene herpetofaunas of southeastern Europe. The single colubroid snake specimen adds further to the published record of Miocene snakes from Greece, whereas the amphisbaenian vertebra from Plakias represents the first described fossil of this group from the country, suggesting that amphisbaenians had a continuous range in the northern Mediterranean area.


Citation
Georgalis, G.L., Villa, A., Vlachos, E. and Delfino, M., 2016. Fossil amphibians and reptiles from Plakias, Crete: A glimpse into the earliest late Miocene herpetofaunas of southeastern Europe. Geobios.

Wednesday, December 7, 2016

Impact of food on an ambush specialist - the Puff Adder

The puff adder, Bitis arietans.
The effect of food availability on the spatial ecology of snakes  is under studied. Snake are low-energy specialists, particularly species that specialize in ambush foraging.  Ambush specialists can feed infrequently and  endure long periods without food. Because they have low-energy requirements, one possible tactic for feeding may be to simply ambush for longer periods when prey availability is low, and decrease the potential costs associated with locating new ambush sites. In a forthcoming paper Glaudas and Alexander  (2017) used radiotelemetry, supplemental feeding, and remote video cameras on free-ranging male puff adders (Bitis arietans) in South Africa to test the hypothesis that food intake affects the foraging ecology of extreme low-energy, ambush foragers. They also quantified their natural feeding rates. Supplementally fed puff adders improved their body condition, spent less time foraging, and decreased distance traveled compared to control snakes. However, movement frequency and home range size did not differ between the two groups. These findings indicate that control snakes traveled farther within similar-sized home ranges compared to fed snakes and did so at no survival cost. Further, naturally foraging puff adders successfully caught a prey of small size once every 10 days on average. Hence, despite their “sit-and-wait” foraging strategy and their low-energy intake/requirements, underfed puff adders travel widely to presumably find appropriate ambush sites that maximize prey capture. This study provides the first strong evidence that the spatial activity of a terrestrial vertebrate species with extremely low energetic demands is significantly affected by
food intake.

Citation

Glaudas X, Alexander GJ. 2017. Food supplementation affects the foraging ecology of a low-energy, ambush-foraging snake. Behavioral Ecology and Sociobiology. 71(1):5.