Natures wonders: arctic squirrel hibernation (Introduction)

by David Turell , Wednesday, December 16, 2020, 19:29 (1436 days ago) @ David Turell

They recycle muscle amino acids over eight months:

https://www.sciencenews.org/article/arctic-squirrels-recycle-proteins-hibernation-survi...

"Arctic ground squirrels can survive harsh winters with below-freezing temps by holing up for some eight months without eating. These hibernators “live at the most extreme edge of existence, just barely hovering over death, and we don’t fully understand how this works,” says Sarah Rice, a biochemist at the University of Alaska Fairbanks.

***

"From autumn to spring, Arctic ground squirrels (Urocitellus parryii) hibernate in bouts of deep torpor. In a state akin to suspended animation, the squirrels breathe just once a minute, and their hearts beat five times per minute. Every two or three weeks, the squirrels revive somewhat for about 12 to 24 hours; their body temperatures rise, and the animals shiver and sleep, but don’t eat, drink or defecate.

***

"By recycling nutrients from their muscles, the squirrels sustain themselves and also avoid a toxic consequence of muscle breakdown, says team member Kelly Drew, a neurochemist also at the University of Alaska Fairbanks. During hibernation, nitrogen would otherwise end up in ammonia, which could build up to potentially deadly levels. Instead, the squirrels are able to incorporate that nitrogen into new molecules, she says.

***

"Other studies have pointed to a role for the microbiome — the microbes living on and inside animals — in recycling nitrogen while animals hibernate, says James Staples, an environmental physiologist at Western University in London, Canada, who was not part of the work. Typically, the breakdown of proteins eventually creates urea, a nitrogen-containing chemical that gets excreted. Microbes can scavenge that urea and release its nitrogen back into the blood. But in the squirrels, the muscle is “being broken down and then recycled directly back into these amino acids … the gut microbiome may not be as important as we thought it used to be.'”

Comment: I would like a Darwinist tell me how this extreme change was evolved. Not step by step by chance. It was designed