Evolution, Selection, Silver Foxes and Adrenaline

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.

Interesting!

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.

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?

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.

Bump

Cool! I missed that one the first time around.

They're pretty, too!

Not surprising, it's a pretty old thread

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.

and here they only wanted a hamster with more dark meat, and , in addition,they got a totally unexpected series of traits

http://retrieverman.wordpress.com/2008/07/10/belyaevs/

Ver-r-r-r-r-r-r-ry interesting. I had no idea.

I'd missed it too..... the first time.

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.

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

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?

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."