New Extremeophiles: antarctic insects (Introduction)

by David Turell , Wednesday, April 15, 2020, 22:54 (1465 days ago) @ David Turell

Survive despite dryness, toxic chemicals for eons:

https://www.scientificamerican.com/article/exotic-creature-in-antarctica-has-survived-m...

"In the decades after Wise's discovery, scientists tried to piece together a rough history of the landscape where Tullbergia was found. Seafloor sediments revealed that Antarctica had experienced 38 ice ages in the past five million years. During those freezes its glaciers thickened, rising inland and cloaking many of the mountain slopes that are exposed today. Temperatures were 5 degrees C to 10 degrees C colder than at present. Most researchers assumed the rising ice sheets “more or less wiped everything out,” says Steven Chown, a polar ecologist at Monash University in Melbourne, Australia.

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"But the results for Tullbergia and Antarctophorus suggested that even in warm times, the movement of these animals was more restricted than people thought. Two populations of Antarctophorus collected from exposed ridges on opposite sides of Shackleton Glacier appeared not to have interbred for five million years—despite the fact that they lived just 10 kilometers apart, the width of the gap that the glacier flows through. “It's quite surprising,” Hogg says. “Five million years is a long time.” It appeared that the species had not traveled at all.

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"The analysis of Tullbergia collected around Shackleton Glacier stunned the researchers even more: the gene sequences from all four sites were virtually identical. “It's like they're all clones,” Adams says. That could mean that all the animals are descended from a couple of individuals and that these descendants have never bred with any outside populations. “That is something that we're all trying to wrestle [with] to explain,” Adams says.

"How could Tullbergia have persisted for millions of years, pinned down by ice during at least 30 ice ages, without moving more than a few kilometers or breeding with other populations? This question is all the more puzzling because for much of that time, these animals were trapped in a narrow zone between deadly ice and deadly salt.

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"Turn over a rock above the trimline at Shackleton or any other Transantarctic mountain, and the soil underneath is often crusted in white salts. “It's not a good salt. It's not Himalayan rock salt,” Adams quips. “Put your tongue on this stuff, and it will light you up.”

"The salt is high in nitrate, toxic to many living things. Nitrate constantly rains down on Earth as ultraviolet radiation reacts with atmospheric gases. In most parts of the world, it does not accumulate in soils, because rain washes it away. But in dry places, like the Transantarctic Mountains, it can build up over millennia, until it reaches toxic levels.

"These high places also accumulate perchlorate, an oxidizing chemical used in disinfectants and rocket propellants—and famous, as discovered by the Phoenix Mars Lander, for making the surface of that planet an unpleasant place.

"The salts create a catch-22 for small animals such as springtails trying to escape advancing glaciers: remaining in place means they will become buried underneath ice, but creeping uphill leads to places that are “just nasty, toxic,” Adams says. “Really crappy habitat.”

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"But with each new ice age, most of the populations died off. Tullbergia bears the scars of that brutal history in its DNA. The fact that every individual from around Shackleton Glacier carries virtually identical gene sequences suggests that at some point in the past, as few as two of the animals managed to survive. Every representative alive today is descended from those progenitors, which may have been lucky enough to be blown by a windstorm onto a patch of Goldilocks ground the size of a basketball court. Tullbergia “came extremely close to extinction,” Adams says."

Comment: It shows us how tough life on Earth can be. My thought is God purposely made it that way to be sure life persisted after its origin .