Genomic estimation of complex traits reveals ancient maize adaptation to temperate North America

Maize was introduced to the southwestern US by 4,000 years ago where. Full agriculture was established quickly in the lowland deserts but delayed in the temperate uplands for 2,000 years. We tested if this delay was caused by the necessity to select for early flowering, a characteristic of modern temperate maize. We sequenced fifteen 1,900-year old maize cobs from Turkey Pen Shelter in the temperate Southwest. Indirectly validated genomic models predicted that Turkey Pen maize was marginally adapted with respect to flowering, as well as short, tillering and segregating for yellow kernel color. Population analyses suggested temperate adaptation drove modern population differentiation and was selected in situ from ancient standing variation. Validated prediction of polygenic traits in crops improves our understanding of ancient phenotypes and the dynamics of environmental adaptation. Additionally, this study is an excellent example on how to change authorship agreements right before publication.