African toad pretends to be a snake


This 21 October 2019 video says about itself:

It is well known that some harmless animals mimic dangerous animals to ward off predators.

Eg, the Brazilian galliwasp lizard poses like a toxic millipede. And the zebra shark can mimic a highly poisonous banded sea snake.

Such posing is called Batesian mimicry. But the Congolese giant toad takes Batesian mimicry to a new level. According to a paper in the Journal of Natural History, the toad not only transform into a very good copy of a Gaboon Viper. It also tries to mimic the hiss the deadly snake make before an attack. The toad also postures so that its front limbs aren’t visible — making it look more snake-like. The Congolese giant toad are found in locations inhabited by the Gaboon viper. The Gaboon viper has the longest fangs and carries the most venom.

From ScienceDaily:

Toad disguises itself as deadly viper to avoid attack

Decades of fieldwork uncover hissing and strike-warning impersonations by toad

October 21, 2019

The first study of a toad mimicking a venomous snake reveals that it likely imitates one of Africa’s largest vipers in both appearance and behaviour, according to results published in the Journal of Natural History.

The Congolese giant toad, a triple cheeseburger-sized prize for any predator, may use its ability to mimic the highly venomous Gaboon viper to escape being eaten. The viper has the longest snake fangs in the world and produces more venom than any other snake.

“Our study is based on ten years of fieldwork and on direct observation by researchers lucky enough to see the toad’s behaviour first-hand. We’re convinced that this is an example of Batesian mimicry, where a harmless species avoids predators by pretending to be a dangerous or toxic one,” says Dr Eli Greenbaum from the University of Texas at El Paso. “To fully test our hypothesis, we’d have to demonstrate that predators are successfully duped, but this would be very difficult in the wild, where the toads are only encountered rarely. However, based on multiple sources of evidence provided in our study, we are confident that our mimicry hypothesis is well-supported.”

The researchers made comparisons between the appearance of the toad, found in central African rainforests, and the viper, which is more widespread in central, eastern and southern Africa. Using live wild-caught and captive specimens, as well as preserved museum ones, they found that the colour pattern and shape of the toad’s body is similar to that of the viper’s head. Most striking are two dark brown spots and a dark brown stripe that extends down the toad’s back, the triangular shape of the body, a sharp demarcation between the tan back and dark brown flanks, and the species’ extraordinarily smooth skin for a toad. Because the Gaboon viper is capable of causing deadly bites, would-be predators likely avoid the similar-looking toads to ensure they don’t make a lethal mistake.

Some mimics are exclusively visual, but for the Congolese giant toad, getting the look right is only part of the impersonation. If a Gaboon viper feels threatened, it will often incline its head and emit a long, loud warning hiss before it actually makes a strike. Similarly, Congolese herpetologist Chifundera Kusamba observed the toad emitting a hissing noise resembling the sound of air being slowly released from a balloon. Over a century ago, American biologist James Chapin observed a bow display by the toad, where the front limbs no longer prop up the viperine-shaped body, which looks similar to the cocked head of a snake threatening to strike.

The final part of the impersonation is getting the location right. Even the best impression will only work if predators of the harmless species are familiar with the venomous one. The researchers compared the geographical range of the toad and viper in the Democratic Republic of Congo (DRC) and found that the Congolese giant toad does not seem to occur in areas where the Gaboon viper is absent. The researchers identified 11 locations in the eastern rainforests where the range of both species overlaps.

Based on speciation dating estimates from genetic data, the Congolese giant toad and Gaboon viper first evolved at about the same time in the early Pliocene about 4-5 million years ago. Considered with their similar appearance, behaviour, and overlapping geographic distribution, the toads and vipers likely coevolved together, further supporting the mimicry hypothesis.

“Given the relatively large size and therefore calorific value of this toad compared to other species, it would make tempting prey to a large variety of generalist predators, including primates and other mammals, lizards, snakes and birds,” says Kusamba, from the Centre de Recherche en Sciences Naturelles, DRC. “Many of these predators use vision to find their prey, and because the viper is deadly venomous, they probably recognise the distinctive, contrasting markings from a considerable distance and avoid the toad because of them, receiving a threatening hiss if the appearance doesn’t put them off.”

Perhaps the best-known examples of Batesian mimicry are in butterflies, where around a quarter of over 200 Papilio swallowtail butterfly species are non-toxic impersonators of toxic ones. Other examples from the animal kingdom include comet fish that fool predators into thinking their tail is a moray eel‘s head, the Brazilian galliwasp lizard that mimics a toxic millipede, and zebra sharks that take on the coloration and undulating movements of venomous sea snakes. Many harmless snakes mimic venomous ones, and some caterpillars, legless lizards, and even birds are able to do so. However, the current study is the first to identify an amphibian mimicking a venomous snake.

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Amphibians of Texel island


This 2015 video is about a male moor frog. He is blue during the mating season.

On 8 October 2019, wildlife warden Anne Sprenkeling wrote about amphibians of Texel island in the Netherlands.

Moor frows are rare in the coastal sand dunes of the Netherlands: they live there only on Texel, and on Schouwen in Zeeland province.

Natterjack toads are rather common on Texel.

Until about 1980, edible frogs were absent on Texel. After that, people introduced them, and they now live in most areas of the island.

Also, common frogs and common newts live on Texel.

Poison dart frog evolution, new research


This 2008 video is called A strawberry poison dart frog mother checks up on her tadpole brood.

From the Smithsonian Tropical Research Institute in Panama:

Imprinting on mothers may drive new species formation in poison dart frogs

What do marrying one’s parents, Oedipus complex have to do with evolution?

October 3, 2019

Summary: By rearing frogs with parents — or foster parents — of different colors, biologists discovered that behavior in response to color may be more important than genetics in the evolution of new species.

The old saying that people marry their parents may be true for poison dart frogs, and it may even lead to the formation of new species, according to a new study in Nature based on work at the Smithsonian Tropical Research Institute (STRI).

Strawberry poison dart frogs live on the mainland in Panama’s Bocas del Toro province and have been isolated on islands in the archipelago that formed during the past 10 million years as sea level rose. Only a single color morph exists on some islands — orange or green, for example, but on other islands several color morphs exist together, like blue and red frogs.

“In the past, people assumed that this group of brightly colored poison dart frogs were warning predators that their skin is toxic,” said Corinne Richards-Zawacki, research associate at STRI and professor of biological sciences at the University of Pittsburgh. “But predators don’t seem to care what color the frogs are, at least based on our earlier experiments. That’s why we started asking whether the way they choose mates might lead to populations of different colors on different islands.”

The team set up three different situations: baby frogs raised with two parents of the same color (red baby, red parents), baby frogs raised with each parent a different color (red baby, one red and one blue parent) and baby frogs raised by foster parents of a different color (red baby, blue parents). In each case they asked which color the female offspring would choose as mates and which color the male offspring would perceive as a rival.

“We discovered that female frogs with parents of the same color tended to choose mates of that same color, whereas frogs with foster parents of a different color would choose mates the color of the foster parents,” said Yusan Yang, who is completing her doctoral thesis at the University of Pitts-burgh. “The same was true for male-male aggression. This tells us that imprinting was more important than genetics when it comes to shaping these behaviors that are based on color.”

When baby frogs were raised with one parent of the same color and one parent of a different color, females chose mates the color of their mother, and males chose rivals the color of their mother, indicating that maternal imprinting was probably more important than paternal imprinting.

They also created a mathematical model showing that male aggression based on imprinting, in concert with female mate choice based on imprinting was enough to cause a scenario to evolve, where like mates with like, which could lead to two color morphs becoming separate species.

“We’re fascinated by the idea that behavior can play such an important role in evolution,” Richards-Zawacki said.

Koolasuchus, big Australian Cretaceous age amphibian


THis 29 September 2019 video says about itself:

Koolasuchus – The Antarctic Amphibian That Ate Dinosaurs

Prehistoric Australia was home to all sorts of strange creatures, including a giant carnivorous amphibian that may have fed on dinosaursKoolasuchus.

World’s biggest salamander, new discovery


This 2019 video is about giant salamanders.

From the Zoological Society of London in England:

New species of giant salamander is world’s biggest amphibian

74-year-old museum specimen

September 16, 2019

Using DNA from museum specimens collected in the early 20th century, researchers from ZSL (Zoological Society of London) and London’s Natural History Museum identified two new species of giant salamander — one of which they suspect is the world’s biggest amphibian.

Chinese giant salamanders, now classified as Critically Endangered, were once widespread throughout central, southern and eastern China. They have previously been considered a single species (Andrias davidianus). However, new analysis of 17 historical museum specimens and tissue samples from wild salamanders challenges this assumption.

The paper, published today (17.09.2019) in the journal Ecology and Evolution, found three distinct genetic lineages in salamanders from different river systems and mountain ranges across China. These lineages are sufficiently genetically different that they represent separate species: Andrias davidianus, Andrias sligoi, and a third species which has yet to be named.

One of the newly identified species, the South China giant salamander (Andrias sligoi), was first proposed in the 1920s based on an unusual salamander from southern China that lived at the time at London Zoo. The idea was then abandoned but has been confirmed by today’s study. The team used the same animal, now preserved as a specimen in the Natural History Museum after living for 20 years at the Zoo, to define the characteristics of the new species.

The other unnamed new species, from Huangshan (the Yellow Mountains), is still only known from tissue samples and has yet to be formally described.

The study’s lead author, Professor Samuel Turvey of ZSL’s Institute of Zoology, said: “Our analysis reveals that Chinese giant salamander species diverged between 3.1 and 2.4 million years ago. These dates correspond to a period of mountain formation in China as the Tibetan Plateau rose rapidly, which could have isolated giant salamander populations and led to the evolution of distinct species in different landscapes.

The decline in wild Chinese giant salamander numbers has been catastrophic, mainly due to recent overexploitation for food. We hope that this new understanding of their species diversity has arrived in time to support their successful conservation, but urgent measures are required to protect any viable giant salamander populations that might remain.

Salamanders are currently moved widely around China, for conservation translocation and to stock farms that cater for China’s luxury food market. Conservation plans must now be updated to recognise the existence of multiple giant salamander species, and movement of these animals should be prohibited to reduce the risk of disease transfer, competition, and genetic hybridisation.”

Chinese giant salamanders are the world’s biggest amphibians. The authors suggest that the newly discovered South China giant salamander — which can reach nearly two metres — is the largest of the three and is therefore the largest of the 8,000 or so amphibian species alive today.

ZSL works in China to protect giant salamanders in the wild and to raise their profile through our exhibit at London Zoo, where zookeepers welcomed four juveniles in September 2016. The salamanders were seized by Border Force after an attempt to illegally import them. One of the salamanders, named Professor Lew, has since moved into a state-of-the-art tank in the Zoo’s Reptile House, where visitors can come face-to-face with one of nature’s giants. The three others are currently being cared for behind the scenes. Keepers will eventually introduce another animal to Professor Lew as a mate and the remaining two may then move to a different zoo, as the adults are highly territorial and need to be housed in separate enclosures.

Melissa Marr, PHD researcher at the Natural History Museum London added: “These findings come at a time where urgent interventions are required to save Chinese giant salamanders in the wild. Our results indicate that tailored conservation measures should be put in place that preserve the genetic integrity of each distinct species. Our research also highlights the central role that The Natural History Museum’s collections can play in the conservation of Critically Endangered species.”

American salamanders and climate change


This video from the USA says about itself:

Plethodon montanus – courtship

Filmed and edited by James A. Organ in the 1960s. Animals are from the Whitetop/Mt. Rogers area, Grayson & Smyth counties, Virginia. See Organ (1958, Copeia, pp. 251-259) for a description of courtship in this population, then known as Plethodon jordani metcalfi. Film provided courtesy of Sylvia Organ.

From Clemson University in the USA:

How salamanders harness limb regeneration to buffer selves from climate change

September 10, 2019

Looking like a cross between a frog and a lizard, the gray cheek salamander has thin, smooth skin and no lungs. The amphibian breathes through its skin, and to survive it must keep its skin moist. As environmental conditions grow hotter or drier, scientists want to know whether and how these animals can acclimate.

Researchers from Clemson University’s College of Science have shown for the first time that these salamanders inhabiting the southern Appalachian Mountains use temperature rather than humidity as the best cue to anticipate changes in their environment. Significantly, the researchers observed that salamanders actually harness their unique ability to regenerate limbs to rapidly minimize the impact of hot temperatures.

The findings, which are described in the paper, “Thermal cues drive plasticity in desiccation resistance in montane salamanders with implications for climate change,” may have implications for other animals and even plants. The paper was published in Nature Communications on Sept. 9.

A major issue for these salamanders each day is the potentially fatal risk of drying out. Biological sciences associate professor Mike Sears and his research group have shown over the years that these animals tolerate dehydration by regulating their water loss through physiological changes. But the researchers didn’t fully understand how they did that until now.

“We’re the first to look on the molecular level at salamander physiology with respect to the environment,” said Sears, whose team conducted acclimation experiments and gene expression analysis. “We figured out from the genetic perspective how they do this.”

Lead author Eric Riddell, who earned his doctorate at Clemson in 2018 and is now a postdoctoral scholar at the Museum of Vertebrate Zoology at the University of California, Berkeley, collected about 150 salamanders from the mountains near Highlands, North Carolina, and brought them back to Sears’ Clemson lab, where he gave them a month to get used to their new environment.

He then divided the animals into four groups that would be exposed to different climate conditions they might experience currently or in the future. Because the animals are nocturnal, he and his undergraduate assistants moved the salamanders from a moist rehydration chamber each night into an activity chamber, where they walked for several hours in soil in the open air as they were exposed to different levels of temperature and humidity.

The researchers repeated this routine over several weeks, while also measuring how quickly the salamanders dried out and how much oxygen they consumed by calculating the vapor pressure deficit (VPD).

“We found that salamanders anticipate the risk of drying out by using temperature and not humidity,” said Riddell, noting that while humidity does play a role in the rate of dehydration, it’s not as reliable a cue for the animals.

Riddell also conducted gene analyses of tissue samples from the salamanders’ skin to understand what physiological changes were occurring at the cellular level that enabled the animals to hold water in their bodies rather than have it evaporate through their skin.

According to Riddell, as temperatures increased, the salamanders were able to break down and subsequently rebuild blood vessel networks in their skin. “This temperature-sensitive blood vessel regeneration suggests that salamanders regulate water loss through regression and regeneration of capillary beds in the skin,” Riddell said.

In the long term, Riddell said, this blood vessel development might help scientists understand a salamander’s unique ability to regenerate or regrow limbs, a model system for understanding regenerative medicine in humans.

“By just focusing on how they regrow this one single type of tissue, these blood vessels, researchers might be able to understand the process of regeneration better,” Riddell said.

This fall, Sears plans to explore what happens as salamanders become more tolerant of warmer temperatures. He and his students will conduct experiments at various elevations to determine the maximum temperature the animal will tolerate voluntarily. Since temperature changes with elevation, the amphibians will select an elevation with an acceptable temperature range.

“Ultimately we want to know how genetically adaptable animals are to changes in the future climate,” Sears explained. “One of the big questions in our field is whether animals can keep up with the rate of climate change through evolution. By leveraging these genomic tools as we did in this study, we can begin to answer such ecological questions.”

In addition to Riddell, other members of Sears’ team contributing to this study included Christina Wells, Clemson associate professor of biological sciences; Kelly Zamudio, Cornell University ecology and evolutionary biology professor; and Emma Roback, a Grinnell College undergraduate summer research intern.

This current study builds on Sears’ groundbreaking research, published in July 2018, which demonstrated the adaptability of seven species of mountain salamanders in adjusting to their changing environment.

Work was supported by grants from the National Science Foundation’s Doctoral Dissertation Improvement Grant (grant number 1601485) and Research Experience for Undergraduates (REU) programs. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Science Foundation. The Highlands Biological Station provided additional opportunities to collect data through its Grant-in-Aid program.

Rare Japanese salamanders, new research


This January 2019 video says about itself:

After the new setup for my group of Hida salamanders (Hynobius kimurae) is finished (setup video and information: here), it’s time to let them move in.

So here’s a short video of these salamanders in their new tank. The group consists of four adult H. kimurae and one adult H. nigrescens.

General information on Hynobius kimurae:

“The Hida salamander (Hynobius kimurae) is a species of salamander in the family Hynobiidae, the Asiatic salamanders. It is endemic to Japan. It lives in deciduous, coniferous, and mixed forests, where it breeds in streams.”

Now, about relatives of these salamanders.

From Kobe University in Japan:

GIS and eDNA analysis system successfully used to discover new habitats of rare salamander

September 6, 2019

A research team has successfully identified an unknown population of the endangered Yamato salamander (Hynobius vandenburghi) in Gifu Prefecture, using a methodology combining GIS and eDNA analysis. This method could be applied to other critically endangered species, in addition to being utilized to locate small organisms that are difficult to find using conventional methods.

The study was conducted by students from the Bioscience team in Gifu Senior High School’s Nature and Science Club (which has been conducting research into the species for 13 years). They were supervised by teachers and aided by university researchers, including Professor Toshifumi Minamoto from Kobe University’s Graduate School of Human Development and Environment. The project was a collaboration between Gifu Senior High School, Kobe University, Gifu University and Gifu World Freshwater Aquarium.

It has been reported that there are approximately 50 Hynobius species of salamander worldwide, around 30 of which are endemic to Japan. Hynobius vandenburghi (until recently known by its previous classification of H. nebulosus), is only found in central and western Japan, with Gifu Prefecture marking the northeast limit of the species’ distribution. However, like approximately 60% of amphibian species in Japan, it falls under the ranking of critically endangered and vulnerable species, mainly due to habitat decline. Only three sites providing habitats for Yamato salamanders had been discovered in Gifu Prefecture up until recently.

The research team utilized a combined methodology of GIS and eDNA analysis with the aim of discovering more Yamato salamander habitats. GIS (Geographic Information System) is a spatial analysis tool that allows data and geographic information to be collected, displayed and analyzed. Environmental DNA analysis involves locating DNA of the species in the environment (in this case in water samples) to understand what kind of organisms live in that habitat.

First of all, environmental factors (such as vegetation, elevation, and gradient inclination and direction) present near the known habitats in Gifu Prefecture were identified, and this information was entered into the GIS to locate new potential habitats. This resulted in a total of five new potential sites being discovered- three in Gifu city and one site each in Kaizu and Seki cities.

Next, each site was visited and water samples were taken. Yamato salamander often lay their egg sacs in shallow water near rice paddies and wooded areas, so the water samples were taken from these environments. The samples were then analyzed for Yamato salamander eDNA. eDNA was discovered in the water from the Kaizu City site, the Seki City site and one of the Gifu City sites.

Field surveys were also conducted to find eggs or adult salamanders at each of the sites where eDNA was discovered. A single pair of egg sacs were found at the Kaizu city site. This lends support to the idea that the combined methodology of GIS and eDNA analysis can be successfully utilized to find new habitats of rare and elusive species like the Yamato salamander.

As this research was carried out by supervised high school students, it is anticipated that this combined methodology can be utilized not only by experts but also as a useful tool for citizen-led conservation efforts. Another advantage of the GIS and eDNA analysis method is that it requires less time, energy and funds compared to conventional field capture (locating animal specimens). This could prove invaluable for identifying and protecting the habitats of endangered species in the face of rapidly declining biodiversity worldwide.