February 27, 2009

Canine family tree reflects human hand

I thought this was interesting. I've heard most of it before. Never seen this article though.


Canine family tree reflects human hand

Last Updated: Tuesday, May 25, 2004 9:38 AM ET
CBC News

Most genetic variation in modern dogs was introduced by humans through selective breeding programs, researchers have found.
This is among the surprising findings of a comparison of dog and wolf DNA by researchers building a canine family tree.

Researchers took DNA samples from 414 purebred dogs representing 85 breeds to see how the canine genome accounts for the smallest Pekinese, curly poodle or herding border collie.

Some modern breeds are less than 200 years old

Scientists used a computer program and statistical analysis to identify a dog's breed based on the subtle differences in its genetic profile.

Geneticist Elaine Ostrander of the Fred Hutchinson Cancer Research Centre in Seattle and her colleagues found the breeds evolved into four main groups:

-An ancient group of older hounds like the Afghan, dogs of Asian origin, such as the Chinese Shar-pei, and the northern Spitz dogs like the Siberian Huskey most closely resembled the wolf.
The Mastifs such as Rottweilers, bulldogs and boxers that share large bodies and square-shaped heads.
-Working dogs like collies and sheep dogs.
-Sporting dogs like hounds and terriers.

Two breeds thought to be ancient, the Ibizan Hound and Pharaoh Hound, in fact aren't so old.

The two hounds resemble dogs depicted on the tombs of pharaohs but they only have traces of ancient fingerprints. The hounds' DNA show they were bred more recently.

The results show although most modern breeds are genetically distinct, the differences evolved in the last several hundred years as humans selectively bred dogs.

Tracking disease genes

Since human families are often too small to get samples from many generations, dog breeds are a useful model for researchers.

Each registered purebred includes many members of an isolated population, which makes it easier for scientists to identify genes behind inherited diseases.

Dogs and humans share many of the same disorders, such as heart disease, cancer and epilepsy. Researchers hope if the can find disease genes in dogs, it will be easier to hunt for similar ones in people.

Veterinary researchers can focus on breeds prone to a disease and owners may be able to determine a pet's lineage.

The study appears in Friday's issue of the journal Science.