The estimated 45 million turkeys that many Americans eat on Thanksgiving are genetically distinct from their wild turkey ancestors.
"Ancient
turkeys weren't your Butterball," Rob Fleischer, head of the
Smithsonian Conservation Biology Institute's Center for Conservation and
Evolutionary Genetics, said in a press release. "We set out to compare the genetic diversity of
the domestic turkeys we eat today with that of the ancestral wild turkey
from South Mexico. Some of what we found surprised us."
He and his colleagues determined that the domestic turkey
that ends up on the dinner table has less genetic variation than
not only its ancestral wild counterparts, which were first domesticated
in 800 B.C., but also than other livestock breeds, such as domestic pigs
or chickens.
The genetic traits affected by the variation are body size
and breast muscle development — features that can help determine the
likelihood of a consumer buying a turkey.
"Few
people know that the commercial turkeys served at Thanksgiving
descended from Mexico, where they were discovered during the Spanish
Conquest and transported to Europe," said Julie Long, senior author of
the study and research physiologist with USDA's Agricultural Research
Service in Beltsville, Md.
"During the next 100 years, Europeans created
many different varieties of the domesticated turkey. It's important to
assess the differences between ancient and modern domesticated turkeys
in the event that some unforeseen problem might threaten the stability
of the commercial turkey lines."
The scientists sequenced the genomes of domestic turkeys from seven commercial lines and
compared them to those of three South Mexican turkeys collected
in 1899 from Chihuahua, Mexico. The ancient turkey samples came from
specimens at the Smithsonian's National Museum of Natural History.
"It
is often the case that selection in domestication reduces the level of
variation," Fleischer said. "What did surprise us, however, is how well
the ancient DNA from the three museum specimens worked to generate the
genome sequences needed to determine the genetic variation and
structure. These data and this approach show great promise for
determining what genes were involved in the process of turkey
domestication."
The findings are published in BMC Genomics.
As a side note, turkeys in the 19th century were often boiled instead of roasted for fancy dinners. I'm guessing that the meat from these birds was tougher, but perhaps more flavorful. Isabella Beeton, the Martha Stewart of her day, wrote about the "noble dish" of turkey in 1859. Some companies still sell free-range "wild" turkeys.
