Mass Extinction That Killed the Dinosaurs Also Led to 'Explosive Radiations of Frogs'

Leon Brooks, Wikimedia Commons // Public Domain
Leon Brooks, Wikimedia Commons // Public Domain

You know what they say: Life finds a way. In this case, we're talking about frog life. Scientists say the mass extinction event that killed off so many dinosaurs may have paved the way for "explosive radiations of frogs," including the nearly 90 percent of species alive on Earth today. They published their report in the journal Proceedings of the National Academy of Sciences.

Previous research has suggested that the frog family party started about 100 million years ago. These studies based their conclusions on analysis of modern frogs' mitochondrial DNA, which can provide a sort of road map to an organism's evolutionary past. But sometimes that map is hard to read or even outdated.

To get a clearer picture, researchers from China and the U.S. decided to look at genes inside the nuclei, rather than the mitochondria, of frogs' cells. They compared nuclear (nucleus-based) genes among 301 different frog species, including one from each of the 55 major branches of the frog family tree.

Oddly enough, branches and trees may have been the key to the frogs' success. Analysis of the frogs' genetic histories suggests that the party really only started about 66 million years ago—just after so many of the dinosaurs were wiped out. It also reveals that nearly 90 percent of frog species today trace their genetic roots to just three frog lineages that survived the mass extinction.

But the researchers say it wasn't necessarily the dinosaurs' disappearance that made our planet a more frog-friendly place. The catastrophe that killed the thunder lizards also killed a lot of other things, including primitive prehistoric plants.

"We think the world was quite impoverished as a result of the [extinction event]," co-author David Wake of UC-Berkeley said in a statement, "and when the vegetation came back, angiosperms dominated. That's when trees evolved to their full flowering."

Seeing their opportunity, frogs began moving into the trees. And up there, they thrived.

Around the same time, Wake says, frog species that stayed on the ground learned their own neat trick: direct development, or skipping the tadpole stage, which requires access to water.

"This certainly draws renewed attention to the positive aspects of mass extinctions: They provide ecological opportunity for new things. Just wait for the next grand extinction and life will take off again. In which direction it will take off, you don't know."

NASA Reveals How Living in Space for a Year Affected Scott Kelly’s Poop

NASA, Getty Images
NASA, Getty Images

When you agree to be part of a yearlong space study, you forfeit some right to privacy. In astronaut Scott Kelly’s case, the changes his body endured while spending a year at the International Space Station (ISS) were carefully analyzed by NASA, then published in a scientific journal for all to see. Kelly submitted blood samples, saliva samples, and cheek swabs. Even his poop was subjected to scrutiny.

As PBS reports, Scott Kelly’s fecal samples revealed that his gut microbiome underwent significant but reversible changes during his time in orbit. In what was surely good news for both Kelly and NASA, his gut bacteria didn’t contain anything “alarming or scary,” according to geneticist Martha Hotz Vitaterna, and it returned to normal within six months of landing on Earth.

Even after being subjected to the challenging conditions of space, “Scott’s microbiome still looked like Scott’s microbiome, just with a space twist on it,” said Vitaterna, who was one of the study’s authors.

The fecal probe was one small part of a sweeping NASA study that was just published in the journal Science, more than three years after Kelly’s return. Dubbed the Twins Study, it hinged on the results of Kelly’s tests being compared with those of his identical twin, retired astronaut Mark Kelly, who remained on Earth as the control subject.

NASA’s goal was to gain insight into the hazards that astronauts could face on proposed long-term missions to the Moon and Mars. The agency has gone to great lengths to get this information, including offering to pay people $18,500 to stay in bed for two months in order to replicate the conditions of anti-gravity.

It also explains why NASA was willing to launch unmanned rockets into space to collect samples of Kelly’s poop. On four different occasions at the ISS, Kelly used cotton swabs to pick up poo particles. When the rockets arrived to drop off lab supplies, they returned to Earth with little tubes containing the swabs, which had to be frozen until all of the samples were collected. The process was tedious, and on one occasion, one of the SpaceX rockets exploded shortly after it launched in 2015.

The study also found that his telomeres, the caps at the ends of chromosomes, had lengthened in space, likely due to regular exercise and a proper diet, according to NASA. But when Kelly returned to Earth, they began to shorten and return to their pre-spaceflight length. Shorter telomeres have a correlation with aging and age-related diseases. “Although average telomere length, global gene expression, and microbiome changes returned to near preflight levels within six months after return to Earth, increased numbers of short telomeres were observed and expression of some genes was still disrupted,” researchers wrote.

Researchers say more studies will be needed before they send the first human to Mars. Check out NASA's video below to learn more about what they discovered.

[h/t PBS]

Astronomers Want Your Help Naming the Largest Unnamed Dwarf Planet in the Universe

iStock.com/jgroup
iStock.com/jgroup

Part of the fun of becoming involved in science is naming things. Entomologists are notorious for branding new species of insects with fanciful names, like the Star Wars fans who labeled apoid wasps Polemistus chewbacca and Polemistus yoda. Sometimes scientists invite the public’s opinion, as in the 2016 petition by the UK's Natural Environment Research Council to have internet users name a polar research ship. They dubbed it Boaty McBoatFace. (That choice was overruled, and the ship is now known as the RRS Sir David Attenborough.)

Now, astronomers are looking to outsource the name of a dwarf planet. But the catch is that there’s no write-in ballot.

The planet, currently known as (225088) 2007 OR10, was discovered in 2007 in the Kuiper Belt orbiting the Sun beyond Neptune and may have a rocky, icy surface with a reddish tint due to methane present in the ice. It's bigger than two other dwarf planets in the Kuiper Belt—Haumea and Makemake—but smaller than Pluto and Eris.

The three astronomers involved in its identification—Meg Schwamb, Mike Brown, and David Rabinowitz of Caltech’s Palomar Observatory near San Diego, California—are set to submit possible names for the dwarf planet to the International Astronomical Union (IAU). They’ve narrowed the choices down to the following: Gongong, Holle, and Vili.

Gonggong, a Mandarin word, references a Chinese water god who is reputed to have visited floods upon the Earth. Holle is a German fairy tale character with Yuletide connotations, and Vili is a Nordic deity who defeated a frost giant.

The team is accepting votes on the planet’s website through 2:59 EDT on May 11. The winning name will be passed on to the IAU for final consideration.

[h/t Geek.com]

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