On this Page:
City Frogs are so Attractive; Plastic Waste and Sea Turtles; Worrying Effect of Chemicals on Frog growth; Green-blooded Lizard; Mystery of Where Chytrid Came From; 'What on Earth' Cornsnake in Brighton, Ranavirus Vaccine; Not so Viviparous; Intensification vs Amphibians; Cuban Boas Hunt in Packs; Conservation Evidence; Geckos Keeping Dry; Cane Toad Invasion; Possible Chytrid Vaccination; Amphibian Life in the City; Amphibians and Drains; What Happens After Amphibian Die-off?; Dreaming Reptiles; Special Sense Organs in Sea Snakes;
City Living May Pep-up Your Sex-life
City Frogs are so Attractive Urban male tứngara frogs in Panama seem to have the edge on their rural cousins. Wouter Halfwerk and colleagues at the University of Amsterdam recorded males in urban and forest locations in Panama. The slick urbanites had more complex calls than their forest counterparts with glissandos, quacks and especially chucks. The team recorded the calls and played them to females to assess their potency. The females were much more likely to be attracted to the urban frog calls, which were richer in chucks. To help explain these findings the researchers looked to see what other animals were attracted by the calls. They played the rural recordings at urban sites and found that the rural calls attracted fewer females, but also fewer biting midges and frog-eating bats. They concluded that in the city attracting females was a greater pressure than the pressure to avoid predators/parasites. To check this hypothesis they sent urban frogs on a forest holiday and forest frogs to the city. The urban frogs rapidly changed their call to the rural call, but the rural frog calls did not change. They concluded that the the urban frogs had evolved to adapt to their new situation. Geckos Walk on Water Film of flat-tailed geckos has revealed how they can skitter across water. Jasmine Nirody, The Rockefeller University, has found that the tails remain in contact with the water. The front legs in a frenzied circular whirl pump air under the body to promote buoyancy and the back legs in the water provide propulsion. Based on articles in 15 December 2018 New Scientist Plastic Waste Impacts on Young Sea Turtles Research in Australia has found that young sea turtles ingest plastic more readily than their elders. Of 246 dead turtles washed up on the shore 58 had between 1 and 329 plastic fragments in their digestive system. Four of the 58 were adults, 41 juveniles and 13 recent hatchlings.A possible explanation is that young turtles swim nearer the surface and so encounter more plastic debris. The CSIRO team led by Brita Hardesty calculated that for young turtles swallowing 17 fragments increased mortality by 50% and one fragment by 22%. The plastic kills by blocking or perforating the gut. |
Worrying Effects on Frog Development
Fluorosurfactants PF are widely used fluorinated hydrocarbons with many uses providing useful properties such as waterproofing, stain resistance, non-stick. However the C-F bond is extremely strong, which means that many of these substances persist in the environment. They can be detected in wildlife and humans
The molecules have a hydrophobic end (CF3) and a hydrophilic end (SO3H) similar to a detergent molecule. Recent work at Purdue University has shown that frogs are particularly affected by these compounds. More….
Fluorosurfactants PF are widely used fluorinated hydrocarbons with many uses providing useful properties such as waterproofing, stain resistance, non-stick. However the C-F bond is extremely strong, which means that many of these substances persist in the environment. They can be detected in wildlife and humans
The molecules have a hydrophobic end (CF3) and a hydrophilic end (SO3H) similar to a detergent molecule. Recent work at Purdue University has shown that frogs are particularly affected by these compounds. More….
A green-blooded skink which is found only on New Guinea was thought to be an evolutionary oddity. It has now been shown by a recent DNA study (Christopher Austin, Louisiana State University) to have evolved at least four times previously. The green colour is produced by a highly toxic breakdown product of haemoglobin, which in other animals is rapidly removed from the body. The breakdown product, bilverdin is known to kill malaria parasites. It is unclear why it does not affect the skink! Click here for more details and pictures of this bright green skink.
Mystery of Where Chytrid Came From
|
Beetle for Lunch? Maybe not
You may be wondering why SxARG have a photo of a Bombardier beetle on their site. Well toads can tell you why. Having partaken of a tasty lunch of beetle the pesky beetle squirts so much hot, toxic fluid into the toad’s stomach that the toad vomits up the beetle, who then goes on his way. Japanese researchers have shown that the beetles can survive up to 2 hours in the toad’s stomach and that 16 out of 37 survived the ordeal. Beetles which had had their defence disabled fared less well with only 3 of the 37 escaping. The bigger the beetle the greater the survival chances. Probably because they could produce more toxic fluid. Based on New Scientist article, 17 February 2018 |
Ranavirus DNA Vaccine for Chinese Giant Salamanders
Just a little brightness on the amphibian disease front. Researchers have developed a DNA vaccine* which improved survival of this endangered species from 3% to 66%. This salamander really is a giant with the potential to grow up to 6 feet in length and 12Kg in weight.. The research article is complex, but can be found here * Genetic/ DNA immunization is a novel technique used to efficiently stimulate humoral and cellular immune responses to protein antigens. The direct injection of genetic material into a living host causes a small amount of its cells to produce the introduced gene products. This inappropriate gene expression within the host has important immunological consequences, resulting in the specific immune activation of the host against the gene delivered antigen |
Zootica vivipara, the common lizard produces live young, rather than laying eggs- but not always. There are 2 populations, one on the Spanish-French border and the other in the Southern Alps where common lizards are egg laying. Kathryn Elmer and her team at the University of Glasgow carried out detailed genetic studies and constructed a family tree. This tree shows that the egg-laying lizards in the southern Alps are a remnant of the ancestral population. Live-bearing lizards evolved once from this ancestral population and split into several different groups. In one of these, evolution went backwards and egg-laying re-evolved, giving rise to the Spanish population. This must have happened relatively recently as live birth only started in these lizards 2 million years ago. Perhaps the genetic programme for egg laying was simply re-activated From New Scientist Dec 17. |
Study on Intensification of Agriculture and Amphibian Population in France
Research paper by Carlos Abrahams et al Finds that rare and common species were less affected by agricutural intensification, but the Northern Crested Newt and Midwife Toads declined. A model of relative resistance to amphibian dispersal was created for different landscape types, on a scale from 0 (low resistance) to 1 (high resistance). This generated values of 0.23 for pasture, 0.72 for arable and 0.98 for urban and transport. Click for full paper
Research paper by Carlos Abrahams et al Finds that rare and common species were less affected by agricutural intensification, but the Northern Crested Newt and Midwife Toads declined. A model of relative resistance to amphibian dispersal was created for different landscape types, on a scale from 0 (low resistance) to 1 (high resistance). This generated values of 0.23 for pasture, 0.72 for arable and 0.98 for urban and transport. Click for full paper
Cuban Boas have been observed hunting bats as a team effort.If there are enough snakes the hunt is 100% effective. This is the first time that snakes have been observed working together to hunt prey. Click here for a magazine summary. Click here for the full scientific paper
Special Sense Organs in Sea Snakes
Sea snakes surprisingly developed from terrestrial snakes. Most terrestrial animals have evolved from aquatic animals such as fish. Land snakes have special sensilla scales on the sides of their head whch are touch sensitive. These sensilla in sea snakes are modified into dome like structures that may be able to detect tiny vibrations inthe water caused, for example, by the fin of a fish. Full details here. |
By William Kreijkes (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
|
Dreaming Reptiles
Almost all animals sleep, but sleep in mammals and birds is a complex process where sleep is divided nto various phases. Mammalian sleep is characterised by periods of slow wave activity, followed by short bursts of neurone activity, which are accompanied by Rapid Eye Movement (REM). Birds are believed to be descended from dinosaurs so Gilles Laurent et al at the Max Planck Institute for Brain Research investigated reptile sleep patterns. They found that the Bearded Dragon, Pogona vitticeps did indeed exhibit both slow wave sleep and REM sleep, similar to birds and mammals, but the reptile sleep cycle was much more rapid lasting just 60 seconds (cat, 30mins, human 90 mins) and slow wave and REM lasted roughly equal lengths of time. All in all the reptile sleep seemed simpler. The suggestion is that sleep patterns came from a common tetrapod ancestor rather than arising separately in reptiles, birds and mammals. Further studies on other reptile groups such as turtles, crocodiles and other lizards should help to strengthen the theory. Click for more information |
What Happens After Amphibian Die-off?
A recent article by Heidi Rantala et al, Southern Ohio University, in Freshwater Biology is unusual because it takes a look at the changes in the ecology of a tropical stream after mass amphibian extirpation caused by the chytrid fungus (Bd). They looked for changes using data from 2006, before the amphibian decline and 2008, 2012 and 2014 after the decline.
Algal biomass (Epilithon) doubled from 2006 to 2012 only to plummet fivefold by 2014. Suspended organic particles declined continuously.
Biomass of filter-feeding, grazing and shredding macroinvertebrates decreased from 2006 to 2014, while collector–gatherers increased during the same time period. Macroinvertebrate taxa richness decreased from 2006 (52 taxa) to 2012 (30 taxa), with a subsequent increase to 51 taxa in 2014.
Community respiration declined through to 2012, but has subsequently recovered. Gross primary production remains low, while ammonium ion uptake declined. Nitrogen flux to algae increased, but to fine organic particles remained low.
There was no evidence of functional redundancy or compensation by other species, even 8 years after the loss of amphibians.
A recent article by Heidi Rantala et al, Southern Ohio University, in Freshwater Biology is unusual because it takes a look at the changes in the ecology of a tropical stream after mass amphibian extirpation caused by the chytrid fungus (Bd). They looked for changes using data from 2006, before the amphibian decline and 2008, 2012 and 2014 after the decline.
Algal biomass (Epilithon) doubled from 2006 to 2012 only to plummet fivefold by 2014. Suspended organic particles declined continuously.
Biomass of filter-feeding, grazing and shredding macroinvertebrates decreased from 2006 to 2014, while collector–gatherers increased during the same time period. Macroinvertebrate taxa richness decreased from 2006 (52 taxa) to 2012 (30 taxa), with a subsequent increase to 51 taxa in 2014.
Community respiration declined through to 2012, but has subsequently recovered. Gross primary production remains low, while ammonium ion uptake declined. Nitrogen flux to algae increased, but to fine organic particles remained low.
There was no evidence of functional redundancy or compensation by other species, even 8 years after the loss of amphibians.
Amphibian Life in the City
Last year nearly 4 000 000 000 tonnes of concrete were poured onto the Earth and 25 000 000km of new road built. Much of this building was on existing wetlands, replacing the spongy nature of wetland with hard surfaces and consequently, excess run-off of rainwater. The solution may be to build storm-water ponds. On investigating these artificial wetlands, Scheffers and his co-author, Cindy Paszkowkdi, from University of Alberta, found: "To our surprise we did find frogs at urban ponds and their offspring were noticeably larger than those in more natural settings". However although the frogs were larger, the population density was much lower. More....
Last year nearly 4 000 000 000 tonnes of concrete were poured onto the Earth and 25 000 000km of new road built. Much of this building was on existing wetlands, replacing the spongy nature of wetland with hard surfaces and consequently, excess run-off of rainwater. The solution may be to build storm-water ponds. On investigating these artificial wetlands, Scheffers and his co-author, Cindy Paszkowkdi, from University of Alberta, found: "To our surprise we did find frogs at urban ponds and their offspring were noticeably larger than those in more natural settings". However although the frogs were larger, the population density was much lower. More....
Research from Yale School of Forestry & Environmental Studies on spotted salamanders in roadside ponds indicates that the harsh environment is driving rapid evolutionary changes. The roadside ponds contain many pollutants, principally salt at 70 times normal levels. Steven Brady found that salamanders in roadside ponds have higher mortality, grow at a slower rate and are more than likely to develop L-shaped spines and other disfigurements. In roadside ponds, only 56 percent of salamander eggs survive the first 10 weeks of development, whereas 87 percent survive in the woodland ponds. The better news is that the salamanders that survive year after year in the roadside ponds appear to have adapted to the harsh conditions. "The animals that come from roadside ponds actually do better -- substantially better -- than the ones that originate from woodland ponds when they're raised together," Brady said. More.....
Meanwhile another Yale study shows that frogs living in suburban ponds are showing unusual male/female gender ratios. This seems to be driven by shrubs and manicured lawns, which seem to produce oestrogens, which accumulate in ponds. David Skelly, director of the Yale Peabody Museum of Natural History, reports: the researchers looked at ponds with varying degrees of suburban neighbourhood impact -- with entirely forested ponds at one end of the spectrum, and ponds that were heavily surrounded by suburbia at the other end. The sites included ponds linked to both septic systems and sewer lines. "Our work shows that, for a frog, the suburbs are very similar to farms and sewage treatment plants," Lambert said. "Our study didn't look at the possible causes of this, partly because the potential relationship between lawns or ornamental plantings and endocrine disruption was unexpected." Phytoestrogens from clover may be the cause of the endocrine disruption. More...
Closer to home, Alexandra North, University of Exeter reports that the severity of ranavirosis, a devastating disease that kills thousands of frogs each year, increases in the presence of exotic fish, eg goldfish. The use of garden chemicals, such as slug pellets and weedkiller was also associated with increased severity of the disease, probably by weakening the immune system. It is also important to avoid moving any material from one pond to another. More.....
How a Gecko keeps Dry
As their body cools below the dew point small. cold-blooded animals provide a surface for condensation to form. Surface moisture can provide good conditions for bacterial and fungal organisms to thrive, perhaps causing infection. A recent article in the Journal of the Royal Society Interface (March 2015) discusses how droplets of water are repelled from a gecko's skin, by the very special topography of the skin. Gecko's, famous for their ability to walk upside down, have another clever trick! Scanning Electron Microscopy of the skin shows an array of dome shaped structures, which provide a hydrophobic surface on which water droplets cannot wet the surface and are ejected keeping the skin dry. Excellent photos can be found in the original article.
As their body cools below the dew point small. cold-blooded animals provide a surface for condensation to form. Surface moisture can provide good conditions for bacterial and fungal organisms to thrive, perhaps causing infection. A recent article in the Journal of the Royal Society Interface (March 2015) discusses how droplets of water are repelled from a gecko's skin, by the very special topography of the skin. Gecko's, famous for their ability to walk upside down, have another clever trick! Scanning Electron Microscopy of the skin shows an array of dome shaped structures, which provide a hydrophobic surface on which water droplets cannot wet the surface and are ejected keeping the skin dry. Excellent photos can be found in the original article.