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Polar bears' ancient roots pushed way back
Science News ^ | Monday, July 23rd, 2012 | Devin Powell

Posted on 07/25/2012 6:22:06 PM PDT by SunkenCiv

...A new analysis of its DNA suggests that Ursus maritimus split from the brown bear between 4 million and 5 million years ago -- around the same time when, some scientists believe, the Arctic's thick sea ice first formed.

With such old origins, the creature must have weathered extreme shifts in climate, researchers report online July 23 in the Proceedings of the National Academy of Sciences. Simulations of how the DNA changed over time suggest that polar bear populations rose and fell with the temperature. After thriving during cooler times between 800,000 and 600,000 years ago, the bears seem to have suffered a genetic bottleneck and crashed after a warmer period that started about 420,000 years ago...

Lindqvist and colleagues had previously dated the emergence of the polar bear to no more than 150,000 years ago... But that research relied on a single fossil containing mitochondrial DNA, genetic material inherited from the mother. In April, the origin was pushed back to 600,000 years ago by Frank Hailer... His team examined more than 9,000 letters in nuclear DNA (derived from both parents) of modern bears.

The new study provides an even clearer picture, says Lindqvist, because it looks at the entire genetic blueprints of 23 modern polar bears... more than 2.5 billion letters in... nuclear DNA... more than 13 million points of comparison.

But the date in the new study was calibrated using the rate at which mutations appear in the DNA of primates, Hailer says...

Isolated brown bears living in Alaska's Admiralty, Baranof and Chichagof islands share between 5 and 10 percent of their DNA with polar bears, Lindqvist's team found. A previous study found that ancient brown bears in Ireland also shared much mitochondrial DNA with their comrades to the north.

(Excerpt) Read more at sciencenews.org ...


TOPICS: History; Science; Travel
KEYWORDS: arctic; dna; emptydna; geneticresearch; godsgravesglyphs; helixmakemineadouble; mattridley; mtdna; polarbears
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To: SunkenCiv
Ain't no party like a Polar Bear Par- taaay !


21 posted on 07/25/2012 9:17:17 PM PDT by Tainan (Cogito, ergo conservatus sum)
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To: SunkenCiv
Unless those are supposed to be 200 year old Great Auks, either the birds or the bear took a really long wrong turn.
22 posted on 07/26/2012 12:58:45 PM PDT by rmlew ("Mosques are our barracks, minarets our bayonets, domes our helmets, the believers our soldiers.")
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To: mamelukesabre
What do you think the chances are that a journalist made a mistake and/or isn't saying what you think they are saying?

“Isolated brown bears living in Alaska’s Admiralty, Baranof and Chichagof islands share between 5 and 10 percent of their DNA with polar bears”

The article goes on to say that polar bears and brown bears interbreed occasionally (much as coyotes and wolves occasionally do) and that this might be a “threat” to the polar bear in diluting what makes them unique.

In light of this I think what the journalist was ATTEMPTING to say is that these particular Brown bears are of 5 to 10% polar bear ancestry - much as some coyote populations are of 5 to 10% wolf ancestry.

So rather than being “SUNSABITCHES” that are “ALL GODDAM EFFING LIARS” - maybe the journalist was unclear in what they were attempting to say?

23 posted on 07/26/2012 1:12:21 PM PDT by allmendream (Tea Party did not send GOP to D.C. to negotiate the terms of our surrender to socialism)
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To: rmlew

These are actually some Not-So-Great Auks, which are rare.

But grilling them for a while should take care of that.


24 posted on 07/26/2012 3:58:03 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/)
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To: mamelukesabre
Make your point, but no need at all to take God's Name in vain as a curse word. God is only to be held in your highest esteem, and any reference to Him must be only in highest reverence. May you repent and receive The LORD’s forgiveness. We all have sinned and come short of His glory, but when we realize that we have sinned, we must be big enough to repent or we will bear His displeasure. I hope you choose to repent. Also, your point may be well taken, but I could not read past the unholy cursing, and did not receive it.
25 posted on 07/26/2012 11:26:49 PM PDT by Bellflower (The LORD is Holy, separated from all sin, perfect, righteous, high and lifted up.)
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To: Bellflower; SunkenCiv

26 posted on 07/26/2012 11:53:21 PM PDT by Daffynition (Our forefathers would be shooting by now.)
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To: SunkenCiv

27 posted on 07/27/2012 1:34:42 AM PDT by Daffynition (Our forefathers would be shooting by now.)
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To: Daffynition

That’s adorable. Of course, after the weight doubled, there weren’t any more games of that kind. ;’)


28 posted on 07/27/2012 5:32:46 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/)
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To: SunkenCiv

29 posted on 07/27/2012 9:51:40 PM PDT by Daffynition (Our forefathers would be shooting by now.)
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