Scientists Create a Dog Breed “Family Tree”

At first glance, a new visual representation of the canine family tree looks more like a pinwheel than a maple, but the researchers who recently mapped out a genetic history of over 160 dog breeds (published in the journal Cell Reports) have provided us with fascinating new insights into the evolution of dog breeds and how they are related to each other…and human history.

Click image to enlarge.

A study was conducted on the genetic data of 1,346 dogs representing 161 different breeds from all over the world.  The researchers discovered that while many breeds are interconnected, there are also some interesting outliers that have few connections with other breeds.  The connections between breeds can happen by chance, with human migrants who bring their dogs with them to other parts of the world, or through direct human intervention via cross-breeding.

As an example, the researchers highlight genetic variation among three breeds in the study (the Tibetan Mastiff, Saluki, and Cane Corso).  DNA collected from populations of these dogs in the US was quite different than DNA collected from the breeds in their countries of origin.  For example, American Cane Corso dogs show much more evidence of intermixing with other breeds (Mastiffs and Rottweilers) than those in their country of origin, Italy.

What are some other interesting findings of the study?

The researchers were able to confirm historical accounts of our creation of bull terrier breeds (for the purpose of dog fighting) through genetics.  All bull and terrier crosses can be mapped to the terriers of Ireland during the years 1860-1870, according to the study.

Speculation that the domestication of dogs first occurred in Central and East Asia is confirmed by genetic testing that identifies Asian spitz-type dogs as among the very earliest breeds.

Dogs traveled from Asia to the Americas 10,000 years ago with the first human migrants.  But the original New World dogs, like the distinctive Xoloitzcuintle, eventually encountered the dogs brought to the Americas by later European migrants and extensively interbred with them, especially herding breeds.

The authors point to two breed types—sighthounds and livestock guardian dogs—as examples of how breeds can develop in different geographic regions (the UK and the Mediterranean in this case) and share similar characteristics but not the same genetic material.  So a trait like speed or large size can be developed in isolation, but the resulting dog can be similar to unrelated dogs from other areas.

Interested in learning more?  You can read the full text and see more illustrations HERE.

 

Cat Genome Project Reveals Clues to Domestication

Birman

A study of the feline genome is providing new insights into how and why cats became domesticated. Compared to dogs, cat domestication is a relatively recent occurrence (30,000 years for dogs vs. 9,000 for cats), but researchers can still find signs of domestication in their DNA.

The lure of treats

Key findings from the cat genome project show that domestication created changes in genes related to memory, fear and reward-seeking. Reward-seeking is particularly important in the domestication process. The promise of a food reward enticed cats to hang around human settlements. Shy, solitary wild cats became more approachable and calm.

Pretty kitty

Analysis of the genes of purebred cats reveals that cats were bred primarily for hair color, texture and pattern, as well as facial features and docility. Researchers point to the Birman (pictured above) as an example. Humans selectively bred Birmans for their white paws. All Birmans have the genetic signature for this trait, and researchers believe this happened in a relatively short period of time.

Designed for hunting

Cats are strict carnivores, and researchers have found specific fat-metabolizing genes that help them digest fatty meats. These genes are not present in humans or animals that eat a more varied diet. Cats have evolved into expert hunters, as reflected by genes for superior hearing and night vision. Interestingly, their sense of smell is more sensitive to the chemical scents of other cats than it is to prey animals.

Click HERE for more information on the cat genome study.

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