Turkeys were important to Central American native cultures. Sabine Eiche reports in her book Presenting the Turkey that Peter Martyr, an early 16th century Italian historian, recorded that thousands were raised and consumed by the court of Emperor Montezuma. Prescott's 1844 History of the Conquest of Mexico relies on Montezuma's written household accounts showing that 8,000 turkeys were eaten in one year. Hundreds were also fed to the carnivores and raptors in Montezuma's menagerie.
Wild turkeys have developed subspecies as they adapt to conditions across North America, http://www.nwtf.org/NAWTMP/about_wild_turkeys.html. All turkeys remain the same species, however, and interbreed freely. In the past, farmers welcomed wild turkey toms into their domestic flocks for a year or two, to invigorate the flock with different breeding.
They also get free and become feral. These turkeys showed up in Christina Tyzzer's yard in Indiana two years ago. She was so enchanted by them, she has gone into the turkey business!