|Red lines indicate species considered Enhydris by Gyi. Names at the end of the red lines are current genera.|
Sunday, September 28, 2014
|Top. Trimeresurus gunaleni. Below its habitat|
Saturday, September 27, 2014
The venom of advanced snakes has been hypothesized to have originated and diversified via gene duplication. Specifically, it has been suggested that both the origin of venom and the later evolution of novelty in venom has occurred as a result of the duplication of a gene encoding a non-venom physiological or “body” protein that is subsequently recruited, via gene regulatory changes, into the venom gland, where natural selection can act on randomly occurring mutations to develop and/or increase toxicity. In short, it has been proposed that snake venom diversifies via repeated gene duplication and neofunctionalisation, a somewhat surprising finding given the apparent rarity of both of these events.
Therefore, the hypothesis concerning the evolution of snake venom is very unlikely and should be regarded with caution, it is nonetheless often assumed to be established fact, hindering research into the true origins of snake venom toxins. To critically evaluate this hypothesis Hargreaves et al. (2014) generated transcriptomic data for body tissues and salivary and venom glands from five species of venomous and non-venomous reptiles. The comparative transcriptomic analysis of these data reveals that snake venom does not evolve via the hypothesized process of duplication and recruitment of genes encoding body proteins. Instead the results show that many proposed venom toxins are in fact expressed in a wide variety of body tissues, including the salivary gland of non-venomous reptiles and that these genes have therefore been restricted to the venom gland following duplication, not recruited. Thus snake, venom evolves via the duplication and subfunctionalisation of genes encoding existing salivary proteins. These results highlight the danger of the elegant and intuitive “just-so story” in evolutionary biology
Hargreaves AD, Swain MT, Hegarty MJ, Logan DW, Mulley JF. 2014. Restriction and recruitment – gene duplication and the origin and evolution of snake venom toxins. Genome Biology and Evolution Advance Access10.1093/gbe/evu166.
Thursday, September 25, 2014
|Limnonectes cintalubang, new species (KUHE 47859)|
The new species, Limnonectes cintalubang is subterranean and all specimens were found at night near burrows on the forest floor. When disturbed they immediately disappeared down the burrow. However, they do not seem to dig the hole by themselves, instead they use burrows constructed by other animals. What species dig the burrows used by this frog is unknown. The skin of the species is exceptionally fragile and tears easily when captured. The eggs of L. cintalubang are creamy white unlike other congeners. Among Bornean frogs creamy white eggs without dark animal hemisphere are known in several genera and all of them breed in deep shaded microhabitats such as small underground streams, in mud, and under leaf litter on the bottom of deep pools. The authors hypothesize that, L. cintalubang lays its eggs shaded localities, possible in water in the burrows.
Limnonectes cintalubang was found in loose slopes of secondary forests with mixed bamboo and broad-leaf trees, always on the ground. The surface of the ground is flat and sparsely covered by dead leaves, but with plant roots and stones densely packing the shallow layers under the soil surface. Frogs were active after 1930 h and each stayed near a burrow up to ca. 5–10 cm in diameter with a long tunnel at a depth of 50–60 cm, it was impossible to dig out the frog. Although only one of about 20 burrows observed had underground water, there was no pool at the immediate vicinity of the holes. The nearest water body was a stream ca. 8–12 m apart from the area. Males did not call in March, July, or December at the type locality. However, females collected in early July possessed large ovarian eggs, the breeding season is thought to include summer seasons. Other species found in association with the present new species in the forest were: Leptolalax gracilis (Günther, 1872), Leptolalax sp., Meristogenys jerboa (Günther, 1872), Nyctixalus pictus (Peters, 1871), and Polypedates leucomystax (Gravenhorst, 1829).
Matsui, M., Nishikawa, K., & Eto, K. (2014). A new burrow-utilising fanged frog from Sarawak, East Malaysia (Anura: Dicroglossidae). RAFFLES BULLETIN OF ZOOLOGY, 62, 679-687.
Behaviors involved in courtship and male-to-male combat have been recorded in over 70 snake species from five families in the clade Boidae and Colubroidea, but before now, scientists had yet to look for evolutionary relationships between these behaviors.
The authors of this study analyzed 33 courtship and male-to-male combat behaviors in the scientific literature by plotting them to a phylogenetic tree to identify patterns. The authors identified the patterns in behaviors, which was not always possible, and then used the fossil record to match the behaviors to the snakes' evolution.
Researchers found that male-to-male combat of common ancestors of Boidae and Colubridae in the Late Cretaceous likely involved combatants raising the head and neck, attempting to topple each other. Poking with spurs may have been added in the Boidae clade. In the Lampropeltini clade, the toppling behavior was replaced by coiling without neck-raising, and body-bridging was added. Snake courtship likely involved rubbing with spurs in Boidae.
In Colubroidea, courtship ancestrally involved chin-rubbing and head- or body-jerking. Various colubroid clades subsequently added other behaviors, like moving undulations in Natricinae and Lampropeltini, coital neck biting in the Eurasian ratsnake clade, and tail quivering in Pantherophis. Although many gaps in the evolution of courtship and combat in snakes remain, this study provides a first step in reconstructing the evolution of these behaviors in snakes.
Senter P, Harris SM, Danielle Kent DL. Phylogeny of Courtship and Male-Male Combat Behavior in Snakes. PLoS ONE, 2014; 9 (9): e107528 DOI: 10.1371/journal.pone.0107528
Wednesday, September 24, 2014
|The restored marsh and Thamnophis gigas. Photo credit CDFW|
Snake Marsh at the Cosumnes River Preserve is home to a genetically unique population of giant garter snakes. With two consecutive years of drought, there was a significant chance of the marsh ponds drying up, potentially causing severe impacts to the snakes.
“The project consisted of well water being pumped into the marsh and the ponds where the snakes live. It was planned and carried-out on CDFW land that is part of the Preserve,” said CDFW Environmental Scientist Eric Kleinfelter. “We had very dedicated contractors and department staff who completed this project in just one month. The Nature Conservancy also played an important role by funding a hydrologic study that showed just how vulnerable to drought this aquatic system is. It was truly a collaborative effort.”
Endemic to California’s Central Valley, the non-venomous giant garter snake is olive to black in color with light yellowish stripes on each side and can grow from three to five feet long. Secretive and difficult to find, this aquatic snake will quickly drop into the water from its basking site before the observer can get close. When threatened, it will excrete a foul-smelling musk. It feeds primarily on fish, frogs and tadpoles and can live up to 12 years.
Located approximately 25 miles south of Sacramento near Galt, the Cosumnes River Preserve consists of approximately 48,000 acres of wildlife habitat and agricultural lands. The Preserve is buffered by a variety of agricultural operations and provides numerous social, economic and recreational benefits to local communities residing in the larger Sacramento and San Joaquin areas. The habitat supports many species of native wildlife, including greater and lesser Sandhill cranes, Swainson’s hawks and waterfowl that migrate throughout the Pacific Flyway.
Saturday, September 20, 2014
In a recently published paper Goller et al. (2014) examined the impact of habitat structural complexity on thermal microhabitats for thermoregulation using the side-blotch lizard, Uta stansburiana. Thermal microhabitat structure, lizard temperature, and substrate preference were simultaneously evaluated using thermal imaging. Lizard thermal preference data were collected by measuring environmental and lizard temperatures simultaneously with an infrared camera. The authors approached a lizard and either filmed at 10 frames/sec or photographed at 0.1 frames/sec for varying lengths of time (minimum of 10–25 min, up to several hours). The environment around the lizard was included in each frame, so that available thermal niches could be assessed.
They found a broad range of microhabitat temperatures was available (mean range of 11°C within 1–2 square meters) while mean lizard temperature was between 36°C and 38°C. Lizards selected sites that differed significantly from the mean environmental temperature, indicating behavioral thermoregulation, and they maintained a temperature significantly above that of their perch (mean difference of 2.6°C). Uta's thermoregulatory potential within a complex thermal microhabitat structure suggests that a warming trend may prove advantageous, rather than detrimental for this population.
A result of climate change will be greater variation and an increase in temperature across the range of Uta stansburiana. Although an increase in several degrees will probably provide a more optimal thermal environment for temperate species, it will also increase the chance of overheating, and rising temperatures may render habitats with less thermal heterogeneity unsuitable for Uta. An increase in temperature may not be detrimental to the study population. Higher thermal microhabitat diversity is important as it may allow behavioral thermoregulation to a preferred temperature in varying temperature conditions. Ability to thermoregulate by moving into shaded microhabitats can be an important buffer of climate change and complex habitats provide shade more reliably.
Goller M, Goller F, French SS. 2014. A heterogeneous thermal environment enables remarkable behavioral thermoregulation in Uta stansburiana. Ecology and Evolution 2014; 4(17): 3319–3329.
Wednesday, September 10, 2014
Varanus olivaceus feeding in a Microcos tree – Polillo,
May 2005. From video by Simon Normanton/ Steel Spyda.
Wednesday, September 3, 2014
Saturday, August 30, 2014
Jeff LeClere, a herpetologist with the Minnesota Department of
Natural Resources, holds an American racer snake Wednesday
morning his team trapped and tagged. Alex Kolyer | MPR news
Monday, August 25, 2014
A dyrosaurid, a marine crocodilian, swimming in the warm
surface waters during the end of the Cretaceous period. Illustration
credit: Guillaume Suan.
Saturday, August 23, 2014
Kucharzewski, C, et al. 2014. A taxonomic mystery for more than 150 years: Identity, systematic position and Malagasy origin of the snake Elapotinus picteti Jan, 1862, and synonymy of Exallodontophis Cadle, 1999 (Serpentes: Lamprophiidae). Zootaxa 3852.2 (2014): 179-202.
Tuesday, August 19, 2014
|Ninia atrata left, Nina franciscoi sp. n. right. T. Angarita-Sierra|
|Nina franciscoi sp n.,top, Nina atrata bottom.|
As for those undescribed Trinidad and Tobago squamates - one of them is a third species of Ninia. Below is typical Ninia atrata.
An adult Giant South American river turtle. The turtle
is the largest member of the side-necked turtle family and
grows up to nearly three feet in length. Photo credit: C.
Ferrara/Wildlife Conservation Society