Vrije Universiteit

A ‘Mysterious’ New Frog Species With Hidden Spots and an Insect-Like Call

Discovered in the Western Ghats of southern India, the species is unique enough to be placed in a newly-created genus as well.

It was after a heavy spell of rain during the 2015 monsoon that Sonali Garg walked out to a spot she had been visiting regularly, and unsuccessfully, for more than two years. A large muddy puddle.

But this time, she struck gold in the form of a new species of frog, Mysticellus franki sp. nov., which turned out to be so unique the study authors have assigned it to a newly created genus.

It all started in 2013 when Garg encountered “strange looking” tadpoles in that muddy puddle when conducting amphibian surveys for her PhD from Delhi University. It was clear the tadpoles belonged to the frog family Microhylidae, but beyond that, “we couldn’t pinpoint what species the tadpoles belonged to,” said Garg in an interview with Mongabay.

When the researchers sequenced the tadpoles and examined the DNA, it was clear that the tadpoles were of a hitherto unknown frog species.

“We have a library of sequences of frogs and other amphibians from the country and we could compare the sequence of the unknown tadpole against them,” said Garg. “To our surprise, the sequence did not match any frog species from the country; it fell into the family [Microhylidae], but beyond that, it did not match anything that was known from India.”

With no knowledge about the adult frog — where it was found, whether it was big or small. Garg and her team started visiting the puddle where they collected the tadpoles regularly. An adult specimen was needed to carry out the necessary morphological analyses to delve into the mysterious new species.

“For the next two years, we kept going back to the same spot. It was the only spot we were sure we would get it,” said Garg. “So we went back there at different seasons and different times of the year because we didn’t know when this frog would come out.”

“Eventually, after two years of this exercise of repeated searching, one monsoon, a couple of days after the monsoon hit, when there was sufficient water that collected on the ground, around the puddles … we saw the frogs. They were there in the hundreds, it was magical. It was as if the frogs were welcoming us,” she added, the excitement still palpable in her voice even after nearly four years.

The new species “was an accidental discovery,” said Garg and supervisor S.D. Biju. “We just happened to be at the right place, at the right time. And of course, often we fail to look closely. In this case, we looked closely at every tadpole, and that’s how this discovery happened!”

Male and female specimens of the newly discovered Mysticellus franki sp. Credit: S.D. Biju

A new species … and a new genus

After making careful notes from the field and recording the calls of the male frogs serenading for females in the puddles, the researchers collected specimens and brought them to the lab to carry out genetic analyses.

A combination of genetic, morphological and call data threw up the final diagnosis. The frog was definitely a new species, and sufficiently different from other members of the family Microhylidae found in India to be assigned to its own genus as well.

The new species belongs to sub family Microhylinae. The genus name Mysticellus is derived from the Latin mysticus, meaning mysterious, and ellus, which means diminutive. The name highlights “the ability of this small frog to remain out of sight despite its occurrence in wayside areas surrounding human settlements,” write the authors in the paper. The species name franki honours Franky Bossyut, a professor and amphibian biologist at Vrije Universiteit Brussel.

“I agree with assignment of the species status. The allocation of a genus status is motivated based on molecular evidence. The evidence is still tenuous because we have one member of the new genus,” said Karthikeyan Vasudevan, senior principal scientist at the Laboratory for the Conservation of Endangered Species (LACONES), Centre for Cellular and Molecular Biology.

“More than anything, it is surprising that it has not been already found and described. While very similar in shape, size, and colouration to other microhylid frogs in southeast Asia, there is nothing in the Western Ghats of India that resembles this,” said David Blackburn, the Associate Curator of Amphibians and Reptiles at the Florida Museum of Natural History. “It is only the secretive nature of these frogs that has resulted in them only now being known to science.”

The new species of frog was discovered when researchers came across a ‘strange’ looking tadpole. After continuously searching for an adult for two years, they spotted around 100 adult frogs around a roadside puddle. Credit: S.D. Biju

Hidden spots and an insect-like call

The researchers observed that the frogs started congregating in hundreds around temporary muddy puddles, two to three days after the first monsoon showers. After four to five days of intense breeding, the frogs disappeared completely, leaving the researchers mystified.

“After we first discovered this frog in 2015, we carried out several surveys in and around the region over a period of three years to study this frog. However, due to its secretive behaviour we were only able to locate it during a very short window of less than four days,” said the authors in an interview.

After the frogs disappeared, the researchers were not able to locate “even a single individual” at any other time of the year. “We don’t know where it hides, lives, and what it does for the rest of the year. The frog’s external appearance does not show morphological adaptations for burrowing. At the same time, we doubt that it simply hides under leaf litter, rocks and stone (the usual hiding places for frogs during the non-breeding time). It’s still a mystery for us,” they said.

When the males called to attract females, they raised the hind part of the body to show off “a pair of black false-eye like spots.” The frogs did the same when the researchers tried to approach them, said Garg.

“The effect is quite startling,” she said. “When the animal is sitting down, the spots are hidden. When we were close to the animal, the frog raised the hind part of its body. This movement really made the spots very visible.”

“The best guess we have is that it’s a defensive mechanism,” she said.

The call of the frog is also quite distinct, observed the researchers. “It resembles an insect chorus,” write the authors in the press release.

The frogs probably had such a unique call to attract females in the most efficient manner, said Garg. “Even if a puddle is crowded with multiple frog species and multiple individuals of the same species, even if it’s pitch dark, the female needs to be able to find her way to the male,” she said. “This is one reason to have unique calls. Also, for this species, with such a short breeding window of four or five days, the pressure to get it right is much higher,” she added.

The frog has two distinct eye-like spots on its rear-end which probably serve as a self-defence feature. Credit: S.D. Biju

A mysterious past

A phylogeny (a sort of family tree) of all known genetic data known from the family Microhylidae shows that the closest relative of the subfamily Microhylinae is the subfamily Dyscophinae, which is restricted to Madagascar.

The available molecular evidence gives us this story. The family Microhylidae would have originated on Gondwanaland, the ancient supercontinent which would eventually break up to form most of South America, Africa, the Indian subcontinent, Australia and Antarctica. When Gondwanaland broke up, the subfamily Dyscophinae took up home in Madagascar and sub family Microhylinae moved on toward Asia on the Indian subcontinent. The split between Dyscophinae and Microhylinae happened about 67 million years ago, giving Microhylinae enough time to diversify in the Indian subcontinent as it drifted along towards Eurasia. Once the Indian subcontinent docked at Eurasia, frogs that make up the Microhylinae subfamily spread all over Asia.

For M. franki in particular, the closest relative on the family tree is the genus Micryletta, also belonging to subfamily Microhylinae but found in the Indo-Burma and Sunderland biodiversity hotspots in Southeast Asia and China.

Using algorithms that can parse out evolutionary timelines by considering the rate at which DNA changes over time, the researchers were able to give tentative dates to different nodes of the phylogeny.

The secretive frogs vanished after appearing for the breeding season which lasted for around four days. Credit: S.D. Biju

“Our study shows that the common ancestors of Mysticellus and Micryletta diverged about 40 million ago. Most likely they originally inhabited the Indian Peninsula and later diverged to give rise to both these genera,” said the authors.
The authors posit that the two genera are likely to have split when the Indian landmass moved close to mainland Southeast Asia through the Myanmar-Malay Peninsula during Middle/Late Eocene.

Karthikeyan Vasudevan from LACONES said, “Recent evidence from the study of arthropods in amber suggests that prior to the final collision at around 55 million years ago with Asia, India moved close to or had land connections with Africa and Europe.” Some models of continental drift show that species could have moved between the Indian subcontinent and Southeast Asia prior to the former’s collision with Asia, he added.

“This might help explain the presence of genera that are not present in the Eastern Himalayas, but are found in South India, Sri Lanka and Southeast Asia,” he added. He gave examples of the skink genus Dasia and the pit vipers (genus Tropidolaemus).

David Blackburn from the Florida Museum of Natural History agrees. “Clearly, some lineages must have survived on India as it moved across the Indian Ocean during the late Mesozoic and early Cenozoic, but several studies, including this one, now support that colonisation of the Indian subcontinent by animals from Asia before India had fully collided with the Asian mainland,” he said.

With inputs from Sahana Ghosh.

This article was first published on Mongabay. Read the original here.

Are the Constants of Physics Constant?

The weird thing about them is that there is no theory to explain their existence. They are universal and they appear to be unchanging.

The weird thing about such constants is that there is no theory to explain their existence. They are universal and appear to be unchanging.

An image of the M101 spiral galaxy, 25 million lightyears away, snapped by NASA’s Spitzer space telescope. Credit: NASA, JPL-Caltech, K. Gordon (STScI) et al.

When Max Born addressed the South Indian Science Association in November 1935, it was a time of great uncertainty in his life. The Nazi Party had already suspended the renowned quantum mechanics physicist’s position at the University of Göttingen in 1933. He had been invited to teach at Cambridge, but it was temporary. Then, the Party terminated his tenure at Göttingen in the summer of 1935. Born took up an offer to work with C.V. Raman and his students for six months at the Indian Institute of Science in Bengaluru. While there, he found that his family had lost its German citizenship rights. He was stateless and without a permanent home. And then, there was this uncertainty about two numbers.

The scientific world had been coming to terms with two numbers that had emerged after a series of discoveries and theories in the previous four decades. They were unchanging and they had no units. One, the fine structure constant, defined the strength of interactions between fundamental particles and light. It is expressed as 1/137. The other, mu (μ), related the mass of a proton to an electron.

Born was after a unifying theory to relate all the fundamental forces of nature. He also wanted a theory that would explain where these constants came from. Something, he said, to “explain the existence of the heavy, and light elementary particles and their definite mass quotient 1840.”

It might seem a little bizarre that Born worried about a couple of constants. The sciences are full of constants—one defines the speed of light, another quantifies the pull of gravity, and so on. We routinely use these numbers, flipping to dog-eared tables in reference books, and coding them into our software without much thought because, well, they are constants. But the weird thing about such constants is that there is no theory to explain their existence. They are universal and they appear to be unchanging. So is the case with the masses of protons and electrons. But time and time again, they are validated through observation and experiment, not theory.

What Born and so many others were after was a unifying theory that would demonstrate that there could only be one unchanging value for a constant. Without this theory, scientists resort to testing limits of a constant. Measuring the constant is a good way to verify that theories using them make sense, that science stands on firm ground. Error from the measurements can be a huge concern. So, instead of validating the masses of protons and electrons, it’s useful to measure the ratio of their masses, a number that is free of the burden of units.

The search for a unifying theory continued. Two years after Born’s lecture, his Cambridge colleague, Paul Dirac, wondered in a Nature paper whether the constants were indeed constant if one were to look at the entire history of the cosmos. Measurements on earth are useful but it is a tiny blue dot in the vast universe. What Dirac asked decades ago is what physicists continue to ask today. Is it a constant everywhere in the universe? Why is it a constant? How constant? The question lingered even as the decades rolled on. “The most exact value at present for the ratio of proton to electron mass is 1836.12 +/-0.05,” wrote Friedrich Lenz in a 1951 Physical Review Letters paper. “It may be of interest to note that this number coincides with 6pi^5=1836.12.” That was the entire paper.

Questioning the constant is really not that far fetched an idea: the existing theories don’t prevent the constants from having a different value. The universe went through three broad phases – the initial radiation dominated phase soon after the Big Bang, a long matter dominated phase, and then a very long dark energy dominated phase that began six billion years ago. One hypothesis is that the mass ratio might have varied only in transitions between the phases. The actual value of the mass ratio (1836.15267389) is not of as much a concern as the uncertainty around its stature as a constant. And scientists have made incredible progress at tackling this uncertainty number.

Later this year, researchers from the Vrije Universiteit in Amsterdam along with collaborators from the University of Amsterdam and the Swinburne University of Technology in Melbourne will publish an overview of their findings in the quarterly journal Review of Modern Physics (the paper is available on arXiv). The mass ratio, they write, varies less than 0.0005%, not enough to call it a change. This is based on telescope observations going as far as 12.4 billion years back in time when the universe was only 10% of its current age.

The conclusion is both mundane and astonishing. Change is so omnipresent that we don’t think twice about how much it is part of our fabric. A human cell might endure a million DNA mutations within a day. Summer’s green leaves become fall’s orange before crackling as winter’s brown under our feet, all within a year. Gases coalesced and gravitated around each other over millions of years, packing into rocks like our water-drenched Earth that orbits the sun. But underneath all that change lies one number that connects them all and a number that has remain unchanged as far as we can see in the cosmos. And we don’t know why. The mu is like scientific gospel that wills the universe into existence.

The history of the cosmos is a good sandbox for measuring drifts in the constant. Since light from the early universe continues to reach earth, radio telescopes are effective tools to study the mass ratio. Ancient light interacts with gases in faraway galaxies and stars before reaching earth. The light arrives at earth with a fingerprint of these gases, which absorb certain frequencies of light. It shows up as absences in the spectrum when reviewing the telescope data. By comparing this fingerprint with lab measurements on the same gas, scientists can deduce the mass ratio variations.

The Vrije Universiteit group is one of a handful of teams in the world that has been on the case of the proton-electron mass ratio for over a decade. They have collaborated with scientists from Australia, France, Russia, Switzerland, the US, the UK, India and the Philippines. They have probed tiny bits of hydrogen, ammonia and methanol hovering billions of years away in space. They have compared signals from the Very Large Telescope in the cold, dry desert of north Chile, from a 100-meter radio telescope in a historic spa town in Germany, and from a 30-meter radio telescope in the Spanish Sierra Nevada. They have even used the Hubble Space Telescope to look at white dwarf stars to see if environments with 10,000 times more gravity than earth would alter the mass ratio.

And… nada. ‘Null result’ is one of the most common phrases in their papers. Which is good. Even a small change of a few percent in the value of the ratio would mean a different universe. A smaller mass ratio could mean a wimpier proton, and possibly a weaker pull for the electrons orbiting the nucleus, leading to different kind of matter.

While the world isn’t very kind to research that doesn’t have anything new to offer, a null result doesn’t mean the matter can be put to rest. Therein lies the quandary which makes the VU team’s research feel like it is equal parts futile and important. No theory in physics can explain the constant mass ratio, the steadfast shepherd of science. It just is, shrug.

Of course, the VU team is not alone in the search. As early as 1996, another team at the Ioffe Physical Technical Research Institute in Russia analysed spectral lines from outer space to gauge variations in the mass ratio. Scientists at Cambridge and at the Swinburne University of Technology have looked for drifts in the fine structure constant. But it is the VU group that has perhaps been occupied with the mass ratio the most. Over more than a decade, this preoccupation has produced one of the most comprehensive and intriguing bodies of work. Year after year, across generations of graduate students and post-docs, they have published a paper that gently picks away at the question from different angles – a more distant spot in the universe, a different gravitational environment, a new tool to measure an old problem.

The aim for future searches is to hunt further back in time and in different environments. Larger telescopes like the European Extremely Large Telescope will help in gathering fainter signals from the universe. And despite the vast measurements, many are in a very narrow slice of the sky. By broadening the field of view, scientists can probe data from other parts of the universe.

The experimental search for a varying constant will likely continue as long as there is no theory to back its existence. A string of null results and small changes to the constant variability helps plug loopholes. As the authors of the Reviews of Modern Physics paper wrote, “Even incremental improvements setting boundaries on drifting fundamental constants are worthwhile to pursue, given the importance of this endeavour into the nature of physical law: Is it constant or not?” Each piece of cosmic doubt is up for scrutiny, to either be nullified in a future experiment or surface as evidence for the next investigator.

Originally published by Scientific American.