Parallel and Intertwining Threads of Domestication in Allopolyploid Cotton.

The two cultivated allopolyploid cottons, and , represent a remarkable example of parallel independent domestication, both involving dramatic morphological transformations under selection from wild perennial plants to annualized row crops. Deep resequencing of 643 newly sampled accessions spanning the wild-to-domesticated continuum of both species, and their allopolyploid relatives, are combined with existing data to resolve species relationships and elucidate multiple aspects of their parallel domestication. It is confirmed that wild and were initially domesticated in the Yucatan Peninsula and NW South America, respectively, and subsequently spread under domestication over 4000-8000 years to encompass most of the American tropics.