Ancient DNA boosts dog knowledge
Researchers have mapped the DNA of one of the world’s oldest dogs to create a better baseline for breed studies.
An international study led by UNSW researchers has mapped the genome sequence of the Basenji dog (Canis lupus familiaris) to improve the understanding of dog evolution, domestication and canine genetic diseases.
The Basenji – also known as the barkless dog – is an ancient African dog breed which still lives and hunts with tribesmen in the African Congo.
The researchers say the genome of the Basenji, which sits at the base of the dog breed family tree, makes an excellent unbiased reference for future comparisons between dog breeds and evolutionary analysis of dogs.
“The dog was probably the first animal to be domesticated by humans and has subsequently been artificially selected by humans into a great diversity of dog breeds of different sizes and shapes,” lead author of the study UNSW’s Dr Richard Edwards says.
“Before this paper, it was difficult to interpret differences between the dog reference genomes and non-domesticated dogs, such as dingoes, jackals, coyotes, wolves and foxes.
“Big changes could be the result of recent artificial selection during creation of the specific reference breed.
“By adding such a high-quality genome at the base of the domestic dog family tree, we have provided an anchor point for studies that can help establish the timing and direction of genetic changes during domestication and subsequent breeding.”
Dr Edwards says the Basenji genome sequence is different to the traditional dog reference genome, CanFam, which is of a highly-derived breed, the Boxer.
He says the choice of dog reference genome can affect the results of future dog genetics studies looking at genetic variants.
“For example, the Boxer is much more closely related to other Mastiffs than other breeds,” he says.
“This may introduce biases in genetic analyses across many dog breeds. There is also the risk that breed-specific variation may map poorly – or not at all – to a biased reference. In principle, the Basenji is equally distant from most modern breeds, making it a less biased basis for comparisons.”
Dr Kylie Cairns is an expert in dingo identity and UNSW researcher. She says the Basenji genome provides a high-quality comparison to all domestic dog breeds for future studies.
“As Basenjis are a very old breed, they provide the perfect comparison to more modern breeds to explore how breeds were developed, the process of domestication and assist in studies looking for disease genes,” Dr Cairns says.
“This genome will also be critical in comparisons to wolves, dingoes and village dogs as an example of an ancient domestic breed.”
She says the Basenji genome may allow scientists to more fully unravel the evolutionary history of early dogs and how humans have shaped the first dogs into the companions and breeds we have today.
“Many people wouldn’t realise that most dog breeds arose in the last 200-300 years,” she says.
“So having access to a high quality reference genome from an ancient breed such as the Basenji gives insight into early breed development and how domestic dogs have been shaped by humans in the last few thousand years.
“We will also be able to tackle lingering questions about the evolutionary history of dingoes and their relatives in New Guinea, with the Basenji acting as a halfway point between non-domesticated dingoes and truly modern dog breeds like pugs, kelpies and poodles. “