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Evolution, Selection, Silver Foxes and Adrenaline

 
 
Reply Fri 15 Dec, 2006 09:17 am
I thought this was interesting...

An article on Dmitri Belyaev

50 years ago a russian scientist named Dmitri Belyaev decided to breed silver foxes, artificially selecting only those foxes with tame characteristics.

What he got was not only foxes with a tame temperment, but he also got foxes with more and more dog-like physical characteristics. At first they had trouble understanding why a selection for temperment would also result in color changes and other physical changes, until they realized that tamability was associated with adrenal chemicals and those systems were near the same gene with melatonin and other skin related hormones.

Selection for tameness resulted in a disruption of the glandular genes, which resulted in a cascade of physical changes associated with those genes.

This is almost certainly what happened to wolves as natural selection affected those which spent more time around humans, eventually resulting in the vast array of dogs we have today.

Additional information on the Silver Fox project
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Type: Discussion • Score: 3 • Views: 5,983 • Replies: 24
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farmerman
 
  1  
Reply Sat 16 Dec, 2006 10:36 am
Obviously, the third leg f Darwins natural selection stool(the Malthusian relationship) is overwhelmed by artificial selection methods and hence, breeding wich artificially "stirs up " the genetic profiles.


"Tame fox" to me , is like a "tame wolverine" Dont never turn your back on the little bastard.
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sozobe
 
  1  
Reply Sat 16 Dec, 2006 10:38 am
Interesting!
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rosborne979
 
  1  
Reply Sat 16 Dec, 2006 03:55 pm
farmerman wrote:
Obviously, the third leg f Darwins natural selection stool(the Malthusian relationship) is overwhelmed by artificial selection methods and hence, breeding wich artificially "stirs up " the genetic profiles.


I found the whole thing very interesting.

I'm still trying to understand how cascades of change seem to occur in some organisms; Bats as an example of a large scale evolutionary change, and Dogs as a very small scale change (though very visible).

Evolution isn't only controlled by the macroscopic world (involving natural selection), it's also affected by the 'environment' of the DNA strand.
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patiodog
 
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Reply Sat 16 Dec, 2006 05:15 pm
Studying my ophtho notes right now, and it is remarkable how essential pigment appears to be (or, rather, something tied to pigment, which is itself tied to the adrenal stuff) in the formation of the globe. Merle animals clearly have some weird pgiment stuff going on -- and they also are prone to a number of ocular agenesis problems (small eyes, incomplete iris formation, and the like).
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rosborne979
 
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Reply Sat 16 Dec, 2006 07:01 pm
patiodog wrote:
Studying my ophtho notes right now, and it is remarkable how essential pigment appears to be (or, rather, something tied to pigment, which is itself tied to the adrenal stuff) in the formation of the globe. Merle animals clearly have some weird pgiment stuff going on -- and they also are prone to a number of ocular agenesis problems (small eyes, incomplete iris formation, and the like).


It was my impression that the connection between various attributes was their location on the DNA strand. I believe the comment from one of the people interviewed on the PBS program said something about 'destabilizing' the DNA in a particular area.

How does a segment of DNA become 'unstable'? What does he mean exactly?
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patiodog
 
  1  
Reply Sat 16 Dec, 2006 08:26 pm
Dunno. What I've been going over may be tied up in neural crest cell migration, so a single mutation could have effects on a number of different systems.

I can imagine that particular regions of a genome could be unstable -- sequence mutations that cause misfolding somehow, susceptibility to transposons or retroviruses -- but I don't know anywhere near enough about genetics to posit a guess. I do seem to remember that distance from the acrosome affects its chances of recombination during meiosis, and genes near a site of translocation would certainly be susceptible to change...

Out of my depth, though, especially these days.
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rosborne979
 
  1  
Reply Fri 30 Jul, 2010 07:38 pm
Bump
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Thomas
 
  1  
Reply Fri 30 Jul, 2010 08:26 pm
Cool! I missed that one the first time around.
Thomas
 
  2  
Reply Fri 30 Jul, 2010 08:35 pm
They're pretty, too!


http://i286.photobucket.com/albums/ll88/guthobla/A2K/domesticfox.jpg
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rosborne979
 
  1  
Reply Sat 31 Jul, 2010 05:00 am
@Thomas,
Thomas wrote:
Cool! I missed that one the first time around.

Not surprising, it's a pretty old thread Smile

It's amazing that selecting for docility (a behavior) coincidentally results in changes to hair and coat (physical changes) simply because the gene for adrenal activity happens to be on the same strand.
farmerman
 
  1  
Reply Sat 31 Jul, 2010 05:51 am
@rosborne979,
and here they only wanted a hamster with more dark meat, and , in addition,they got a totally unexpected series of traits


  http://4.bp.blogspot.com/_z0BZmM0Wpf8/S12qbe9XaKI/AAAAAAAAAFQ/_oOPXZ_4Jdw/S748/hamster.jpg
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ehBeth
 
  1  
Reply Sat 31 Jul, 2010 06:12 am
http://retrieverman.wordpress.com/2008/07/10/belyaevs/
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edgarblythe
 
  1  
Reply Sat 31 Jul, 2010 07:38 am
Ver-r-r-r-r-r-r-ry interesting. I had no idea.
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littlek
 
  1  
Reply Sat 31 Jul, 2010 07:45 am
I'd missed it too..... the first time.
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rosborne979
 
  1  
Reply Sat 31 Jul, 2010 07:58 pm
Hmmm, I'm glad I revived this thread. It seems to have slipped by the first time.

It's definitely an interesting concept, and very important for anyone trying to understand evolution.
farmerman
 
  1  
Reply Sun 1 Aug, 2010 03:51 am
@rosborne979,
I got this article from SCITABLE. Its about pleiotropy and has a nice little bibliography at the end, and a good little extended subject for detailed understandings of other areas of genetics.



Pleiotropy insures that evreything comes at a cost

littlek
 
  1  
Reply Sun 1 Aug, 2010 07:13 am
@farmerman,
Th8is sounds like it could be a suit of traits that may have evolved together for a specific environment. But, this is a bred chicken, not a wild one?

Quote:
along with producing defective feathers, the frizzle gene caused the fowl to have abnormal body temperatures, higher metabolic and blood flow rates, and greater digestive capacity. Furthermore, chickens who had this allele also laid fewer eggs than their wild-type counterparts, further highlighting the pleiotropic nature of the frizzle gene.
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Thomas
 
  1  
Reply Sun 1 Aug, 2010 12:17 pm
@rosborne979,
In An Ancestor's Tale, Richard Dawkins dedicates a few pages (pp 29--32) to Belyaev and his tame Sibirian foxes. He suggests that "breeding for tameness" really works out to breeding against the onset of adulthood. In a lot of ways, Belyaev's tame foxes behave like the pups of regular foxes. Similarly, modern dogs behave much like baby wolves.

From this observation, Dawkins goes on to speculate that a similar process of taming might have happened to us. Humans look but much more similar to baby chimpanzees than to adult chimpanzees. The same is true on the level of hormones: Among chimpanzees, only babies can digest milk. Adults, by contrast, are almost universally lactose-intolerant. Human adults, by contrast, usually digest milk just fine---just as you would expect from a species whose members never fully grow up.

Dawkins concludes with a picture that still makes me smile: "Is lactose tolerance just the tip of the iceberg? Are our genomes riddled with evidence of domestication affecting not just our biochemistry but our minds? Like Belyaev's domesticated foxes, and like the domesticated wolves that we call dogs, have we become tamer, more loveable, with the human equivalents of floppy ears, soppy faces, and wagging tails? I leave you with the thought, and move hastily on."
edgarblythe
 
  1  
Reply Sun 1 Aug, 2010 12:22 pm
@Thomas,
Razz
0 Replies
 
 

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