Fig 1. Geographical location of sampled populations and experimental fields.

The entire set of 37 Mexican teosinte populations is shown with parviglumis (circles) and mexicana (triangles) populations sampled along gradient a (white) and gradient b (black). The 11 populations indicated with a purple outline constituted the association panel. This panel was evaluated in a four-block design over two years in two experimental fields located at mid-elevation, SENGUA and CEBAJ. Two major cities (Mexico City and Guadalajara) are also indicated. Topographic surfaces have been obtained from International Centre for Tropical Agriculture (Jarvis A., H.I. Reuter, A. Nelson, E. Guevara, 2008, Hole-filled seamless SRTM data V4, International Centre for Tropical Agriculture (CIAT), available from http://srtm.csi.cgiar.org).