Luminescent amphibians, new research


The ability to glow in a range of colors from green to yellow when exposed to blue light is common among amphibians like this green Pacman frog (Ceratophrys cranwelli), a new study reports. Photo J. Lamb, M. Davis

The ability to glow in a range of colors from green to yellow when exposed to blue light is common among amphibians like this green Pacman frog (Ceratophrys cranwelli), a new study reports.

By Erin Garcia de Jesus, February 27, 2020 at 11:00 am:

Glowing frogs and salamanders may be surprisingly common

Blue and UV light can make patterns invisible to humans in natural light appear on amphibians

Many animals — from marine species like fish to corals and land creatures like penguins and parrots — have a hidden skill: gleaming blue, green or red under certain kinds of light (SN: 11/17/17). But when it comes to amphibians, experts knew of only one salamander and three frogs that fluoresced — until now.

Jennifer Lamb and Matthew Davis, biologists at St. Cloud State University in Minnesota, shone blue or ultraviolet light on 32 species of amphibians, including salamanders, frogs and the wormlike caecilian, at varying life stages. To their surprise, all lit up, turning brilliant shades ranging from green to yellow, the researchers report February 27 in Scientific Reports.

The effect was strongest under blue light. Among all four-legged creatures, the ability to absorb higher-energy blue light and emit lower-energy green light had previously been documented only in marine turtles. The new finding suggests that biofluorescence is widespread among amphibians.

Different species glow in different patterns, the team found. Some, such as the eastern tiger salamander (Ambystoma tigrinum), reveal strips or blotches of color. In others, like the marbled salamander (A. opacum), bones and parts of their undersides light up.

Although the researchers didn’t test the mechanisms that amphibians use to glow, the animals may rely on fluorescent proteins or pigment-containing cells. Multiple mechanisms would hint that the ability evolved independently in different species, rather than being passed down by an ancient ancestor of modern amphibians.

Biofluorescence may help salamanders and frogs find one another in low light: Their eyes contain cells that are especially sensitive to green or blue light (SN: 4/3/17). Scientists could also harness the amphibians’ ability, using special lights to search for the animals during biodiversity surveys — particularly for those creatures that blend into their surroundings or hide in piles of leaves. Lamb already has hints that might work. As she’s prowled her family’s woods at night with blue light in hand, she’s spotted the telltale glow.

Olm salamanders in Slovenia, video


This 29 January 2020 video from Slovenia says about itself:

The caves beneath Predjama Castle are home to the remarkable olm salamanders. Their eerie pale skin and the fact that they possess both gills and lungs is why people call them ‘the human fish’.

Axolotl salamanders, genome research


This 2016 video says about itself:

Named for an Aztec God, This Species Is Critically Endangered | National Geographic

This unique salamander in Mexico is now fighting against extinction.

From Yale University in the USA:

Tiny salamander’s huge genome may harbor the secrets of regeneration

January 28, 2020

The type of salamander called axolotl, with its frilly gills and widely spaced eyes, looks like an alien and has other-worldly powers of regeneration. Lose a limb, part of the heart or even a large portion of its brain? No problem: They grow back.

“It regenerates almost anything after almost any injury that doesn’t kill it,” said Parker Flowers, postdoctoral associate in the lab of Craig Crews, the John C. Malone Professor of Molecular, Cellular, and Developmental Biology and professor of chemistry and pharmacology.

If scientists can find the genetic basis for the axolotl‘s ability to regenerate, they might be able to find ways to restore damaged tissue in humans. But they have been thwarted in the attempt by another peculiarity of the axolotl — it has the largest genome of any animal yet sequenced, 10 times larger than that of humans.

Now Flowers and colleagues have found an ingenious way to circumvent the animal’s complex genome to identify at least two genes involved in regeneration, they report Jan. 28 in the journal eLife.

The advent of new sequencing technologies and gene-editing technology has allowed researchers to craft a list of hundreds of gene candidates that could responsible for regeneration of limbs. However, the huge size of the axolotl genome populated by vast areas of repeated stretches of DNA has made it difficult to investigate the function of those genes.

Lucas Sanor, a former graduate student in the lab, and fellow co-first author Flowers used gene editing techniques in a multi-step process to essentially create markers that could track 25 genes suspected of being involved in limb regeneration. The method allowed them to identify two genes in the blastema — a mass of dividing cells that form at the site of a severed limb — that were also responsible for partial regeneration of the axolotl tail.

Flowers stressed that many more such genes probably exist. Since humans possess similar genes, the researchers say, scientists may one day discover how to activate them to help speed wound repair or regenerate tissue.

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.