Presented by Matthew Hufford, Iowa State University

Abstract: Maize, like many crop species, colonized a much larger area following its domestication in southwest Mexico. This period of expansion involved complex demographic changes and required adaptation to novel environments including multiple highGelevation regions. Based on highGdepth reGsequencing data from 31 maize landrace genomes spanning the Americas, we have investigated how demography and adaptation have shaped the maize genome during its spread away from Mexico. We reveal a continuous genetic bottleneck in maize landraces starting from approximately 10,000 BP and lasting to 1,000 BP, with decreasing genetic diversity in maize with increasing distance from its center of origin. Andean landraces, at the expansion wave front, exhibit the lowest diversity, the highest level of derived homozygous genotypes and runs of homozygosity, and the highest genetic load. Previously detected introgression from teosinte (Zea mays ssp. mexicana) into Mexican highland landraces was also confirmed and unreported introgression was found extending into the Guatemalan highlands and the southwestern US. Our data suggest this introgression has conferred highGelevation adaptation to maize in Mesoamerica, but that a novel process of adaptation characterizes maize in the high elevations of the Andes.

Join us for refreshments in the Molecular Biology Building  atrium at 3:45 p.m. before the seminar.

Host: Eve Wurtele (mash@iastate.edu)