Science roundup: Romeo meets Juliet and save their species

A new species of whale, the evolution of seals and a transparent lizard; plus other stories from around the world

Wednesday 10 April 2019 16:45 BST
A frog believed to be the last of its kind seems to have finally found a mate
A frog believed to be the last of its kind seems to have finally found a mate (Reuters)

Romeo, meet Juliet – now go save your species

At first, the story of Romeo, the last Sehuencas water frog, seemed like an ecological tragedy. Here was an animal in an aquarium destined to live as a bachelor, passing with his kind into extinction.

But then there was Juliet.

After biologists found her leaping from a waterfall at the end of a Bolivian stream, they took her back to Romeo’s home at the Museo de Historia Natural Alcide d’Orbigny in Bolivia to see if they’d hit it off.

These lovers’ stars do not appear to be crossed. Their first meeting was a success and if their mating is productive, it could mean restored hope for their species, and for the conservation of other amphibians threatened by habitat destruction, exotic species, pollution, climate change and chytrid fungus (recently declared far worse than thought).

“This first date is a significant chapter in what we hope will be a long story with a happy future for the Sehuencas water frog,” says Robin Moore, communications director at Global Wildlife Conservation and a photographer who has been following Romeo and other threatened frogs.

Last month, Romeo and Juliet met for the first time after both were cleared of a deadly fungal disease that one might have passed to the other.

At their first meeting, on 1 March, the two spent a few minutes making introductions in a small tank in the museum. Their date was so successful that the frogs have been living together in Romeo’s aquarium ever since.

In Romeo’s habitat, they were more comfortable. The moment Juliet moved there, Romeo started singing. This surprised researchers, who had worried that Romeo had stopped making his mating calls because he was too old to reproduce. But his croaking meant he was ready to breed.

To mate, frogs embrace in a position called amplexus: the male frog clings to the female until he can fertilise her eggs as she lays them. During this time, the male often won’t eat – for weeks or even months – until the deed is done.

Romeo is giving up his worm meals for Juliet and trying his best to perfect amplexus. But after a decade of solitude, “he needs more practice”, says Teresa Camacho Badani, a herpetologist at the museum who found Juliet.

Romeo embraced Juliet briefly, making a new vocalisation his handlers had not previously heard, and wiggling his back toes. These “jazz hands” or “twinkle toes”, as researchers are calling them, have never been observed in water frogs. They may be a signal to impress mates or defend against competition.

By observing and trying to breed four other Sehuencas water frogs the team captured (two males and two females), they hope to learn if these behaviours are unique to Romeo and Juliet or common to the species.

An elusive whale is found all around the world

Salvatore Cerchio stunned the small world of whale science in 2015 when he found examples of a new species in the wild for the first time. Now, he’s mapped the habitat of that species, called Omura’s whale after Hideo Omura, a prominent Japanese whale biologist.

The surprise in the new study, published in Frontiers in Marine Science, is that Omura’s whales, though little seen, are widespread across the tropical world.

Cerchio, a researcher with the New England Aquarium in Boston, found a population off the northwest coast of Madagascar, where he works, and compiled reports of sightings from Japan, Australia, Brazil and off the coasts of Indonesia, among others. In total, from photographs, audio recordings, museums and documents, he identified 161 accounts of Omura’s whales in 95 locales.

Scientists say the finding is a reminder of how little we actually know about what goes on in the world’s oceans.

“To me, this is a beautiful example of how much we didn’t know and how much we can know,” says Christopher W Clark, a retired senior scientist at Cornell University, who was not involved in the research.

Technological innovation in recording devices, advances in genetic analysis – and simply knowing what to look for – seem to have led to the new insights.

Clark, an expert in whale acoustics, says that for decades researchers simply dropped the equivalent of a cassette recorder off the side of a boat, recorded for as long as the tape lasted, and then pulled it back up. Today’s more sophisticated devices allow researchers to position recorders at the bottom of the sea for six to 12 months at a time. The devices also can detect a wider range of tones, enabling them to hear the low notes of Omura’s whales for the first time.

Clark says he plans to go back into his own recordings to search for the animal’s signature sounds. “I know there are places that I’ve recorded Omura’s whales in the last nine months,” he says.

They sing at such a low frequency, Cerchio says, that when he was diving in their habitat, he felt rather than heard their distinct, rhythmic patterns of song, and typically had to speed up the recordings to actually hear them.

Scientists discovered the evolutionary path of leopard seals that took them into the water (Getty/iStock)
Scientists discovered the evolutionary path of leopard seals that took them into the water (Getty/iStock) (Getty Images/iStockphoto)

How seals took to the seas

Oceans today are home to a variety of seals, ranging from leopard seals darting through Antarctic surfs in pursuit of a penguin to endangered Hawaiian monk seals lounging on sunlit shores.

But how did seals first take the evolutionary dive into the oceans more than 30 million years ago? Palaeontologists know that seals’ ancient ancestors lived and walked on land. But what helped transform them into marine mammals is a tale riddled with holes.

Recently, a pair of researchers studying prehistoric seal fossils and remains of modern species discovered a new piece of the story. They reported last month in the Journal of Vertebrate Palaeontology that contemporary seals attack and bite their prey using much the same technique that their ancestors did millions of years ago.

Morgan Churchill, a palaeontologist at the University of Wisconsin, Oshkosh who was not involved in the work, called this study of seals, “the first comprehensive analysis that’s looked at the skulls and mandibles of living species that also incorporates fossils”.

Their finding suggests that the ability to bite was an evolutionary adaptation that contributed to the animals’ ability to make a successful transition from land to water, says Sarah Kienle, a comparative biologist at the University of California, Santa Cruz who led the research.

“It makes sense because they evolved from terrestrial carnivores,” Kienle says. She adds that seal ancestors were “able to take a feeding strategy that they were doing on land and successfully translate that to the water environment”, a technique that has allowed these marine mammals to thrive and diversify into a variety of ocean habitats some 30 million years later.

A graduate student at the University of Georgia recently discovered how to gene edit a lizard using Crispr (Getty/iStock)
A graduate student at the University of Georgia recently discovered how to gene edit a lizard using Crispr (Getty/iStock) (Getty Images/iStockphoto)

Introducing the world’s first gene-edited lizard

Scientists have been altering the genes of mice, pigs, goats, chickens and butterflies for quite some time. But even as Crispr, a transformative gene-editing tool, made seemingly impossible genetic alterations possible, reptiles had remained untouched.

That changed with the birth of a nearly transparent Anolis lizard, the first gene-edited reptile, according to the draft of a study made public last week.

Ashley Rasys, a graduate student at the University of Georgia who was involved in the lizard’s creation, arrived shortly after it broke through its thick M&M-size shell.

“I was floored,” she says.

“We weren’t really expecting to generate an albino lizard at first.”

The steps involved in creating him are outlined in the paper, which was first reported by Science magazine. Scientists now have another model to utilise in genetic research.

“When we want to understand human biology we go to one of these model systems,” says Douglas Menke, director of the genetics department at the University of Georgia and another author of the study. Until now, all 10,000 species of reptiles have been off-limits. “People thought they were just too hard to work with,” he says.

The challenge was figuring out how to access lizards’ reproductive systems in the right way at the right time. What his team has proved, he says, is that it is possible.

“We can now create two to four mutant lizards from just a day’s work,” he says.

It took the scientists about two years to figure out how to access the reproductive system of the lizards in the desired way. Then they had to use their genetic scalpel to target the lizard mum’s eggs, while they were still growing inside her.

The scientists could have altered a variety of genes, but they focused on the mutation that codes for albinism in large part because that tweak is visual. Producing an albino lizard would show their gene editing was successful.

Phobos is pictured eclipsing the sun in 2013. On March 26, both Phobos and Mars’s other moon Deimos eclipsed the sun (Nasa)
Phobos is pictured eclipsing the sun in 2013. On March 26, both Phobos and Mars’s other moon Deimos eclipsed the sun (Nasa) (NASA/JPL-Caltech/Malin Space Sci)

Watch two tiny moons eclipse the sun on Mars

The cameras of Nasa’s Curiosity rover usually look down at the rocks on Mars, divining clues in the minerals of what the planet was like billions of years ago.

Sometimes the rover also looks up. In March, it spotted two eclipses.

Eclipses on Mars are not quite as total as those sometimes seen on Earth when the moon completely blots out the sun. The two moons of Mars are small: Phobos is 17 miles wide; Deimos is even tinier, just 9 miles in diameter. They only partially block the sun when they pass in front of it.

The camera on Curiosity’s mast is equipped with solar filters that allow it to look directly at the sun and photograph eclipses. On 26 March, Curiosity observed Phobos eclipsing the sun. Nine days earlier, it also spotted Deimos passing in front.

Although Phobos does not completely eclipse the sun, the Martian satellite does block it enough to momentarily darken the sky. Another camera on Curiosity noticed the dimming of the landscape on 25 March as the shadow of Phobos passed over the rover at sunset.

The observations by Curiosity – and by earlier Nasa Mars rovers, Spirit and Opportunity – enable more precise pinpointing of the moons’ orbits, which are jostled around by the gravity of Mars, Jupiter and even each other.

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