How to Build a Dog - Report from National Geographic

I didn't used to subscribe to National Geographic. But they cancelled another magazine I used to read and just started sending Nat Geo in its place -- and I'm kind of glad they did. There has been some interesting stuff lately in Nat Geo.

In the February issue, there is an interesting story about DNA differences in breeds of dogs. It's a pretty short article, so I recommend that you read it in its entirety.

The nuts and bolts of the article is essentially how cut and dried dog DNA is.

There are some 400 dog breeds in the world.  When scientists began studying canine DNA, they expected all of the huge size/coat/shape differences to be caused by a crazy mix and match of different gene mutations (as was often the case in other species).

However, dogs didn't evolve naturally. They were purposefully bred for specifc traits and thus, essentially sped up the pace of evolution. And what has resulted is that the variety of dogs shapes, colors and sizes is largely determined by only about 50 different genes.  Because of the artificial selection, breeders chose to highlight genes that had a significant impact in physical traits.

For example, the difference between a Dachshund and it's small, body and short legs, and the massive size of the Rottweiler is determined by the sequence of a single gene.  The difference between the dachshund and a greyhound rests solely on the sequence of a different gene.

To put this into comparison, something a simple as human height is determined by the interactions of more than 200 gene regions.

All of this gives us a pretty good feel for how certain things like DNA testing for dogs may end up being much more reliable than previously thought.

Also of note, is that researchers have been using dogs to help study diseases in humans. There are some types of dogs that are much more prone to certain types of diseases and cancers -- and because the difference in dogs rests on a couple of gene strains, it gives researches a much smaller window of places to look when they then look for the same gene strains in humans.

That's pretty cool.

It's an interesting piece -- and worth the time to read to get a chance to know our dogs a little better.

Picture credit: National Geographic

Comments

[Dianne R.]

There was a companion piece on nat geo tv that I caught by accident (after watching Cesar on nat geo wild). It was fascinating. It also included some tests comparing dogs with wolves raised and socialized by people; eg very tame. Dogs look to human for cues; wolves do not. Very interesting to me as dogs and wolves have the same mitochondrial dna - so wolves are probably more like a "breed" of dog rather than a separate species. Also the slippery genome also exists in wolves, coyotes, and foxes. Dogs and wolves and coyotes can breed and produce fertile offspring. In fact, one reason the eastern grey wolf is smaller than its western counter part is interbreeding with coyotes. And if you've ever taken a road trip in Alaska you've seen all the signs for wolf-hybrid puppies.

[Brent]

Interesting Dianne. Recently, Nat Geo the magazine ran an article about the Silver Foxes study in Russia. I wrote about it here:

http://btoellner.typepad.com/kcdogblog/2011/04/the-science-of-domesticating-foxes-what-it-may-tell-us-about-genetics-in-dogs.html

One thing I thought was really interesting was that in foxes (and in dogs), the thing that actually makes them domesticated is a genetic defect that makes them more trusting than they naturally would be. Obviously this is something that wouldn't do well in the wild (good way to get killed) but would be desired in an artificial selection setting.

[Central Ohio Dog Blog]

So can we also read this to mean that it doesn't take many cross-breedings to get a dog that looks substantially different than its ancestor? I imagine that with only 200 gene sequences to choose from, even two generations out may look starkly different than its grandparent.

I ask this not only because I think it's silly when people try to guess a dog's breed from its look, but also because it has pretty stark ramifications in places (like Ohio) where dogs live or die depending on how much they resemble certain "breeds."

[CristyF]

I love National Geographic Magazine, I read it online. :)

Dog genetics is fascinating. I don't put much stock in those DNA tests to determine breed though, I know somebody who's pointer mix came back as being mostly maltese.