Fig 1.
Historical timeline of pre-Columbian maize cultivation by geographical region and some Pre-Columbian cultures linked with maize cultivation.
Figure created using available historical and archeological records [4,5,6,7,8].
Fig 2.
Geographic origins and typical altitude of growing environment of 194 maize native populations and extent of Pre-Columbian cultural regions in the Americas.
Fig 3.
Neighbor-joining cluster analysis of 38 maize landrace populations from Mexico based on proportion of shared alleles from 28 SSR markers.
Populations are labeled according to race name and are colored according to the classification of racial complexes [26].
Table 1.
Assignment of the Mexican populations in each group determined by population structure analysis for K = 4 and K = 6.
Fig 4.
Neighbor-joining cluster analysis of 194 maize populations from Latin America and the Caribbean based on proportion of shared alleles from 28 SSR markers.
Populations are labeled according to ID number and colored according to altitude where the accessions were grown.
Fig 5.
Relationships of 194 native populations from Latin America and the Caribbean revealed by Principal Coordinate Analysis based on proportion of shared alleles.
(A) populations identified with ID number and colored according to groups found in cluster analysis (Fig 4), and the ancient indigenous landraces are indicated: Palomero Toluqueño (PT), Arrocillo Amarillo (AA), Chaplaote (CH) and Nal-Tel (NT) from Mexico, Pollo (Pll) and Pira (Pi) from Colombia, Avati (Av) from Paraguay, and Confite Morocho (CM), and Confite Puneño (CP) from Peru. (B) populations identified with ID number but colored according to altitude where the accession was collected.
Fig 6.
Geographical distribution of 194 maize populations from Latin America and the Caribbean estimated by population structure analysis.
(a) Structure analysis for all 194 accessions that identified three main groups: Mexico and Southern Andes group (G1), Mesoamerica lowland (G2), and South America-Andean region (G3). (b) sub-structure analysis of G1 that identified three sub-clusters: northern Mexico (g1), central Mexico (g2) southern Andes (g3). (c) sub-structure analysis of G2 that identified 4 sub-groups: tropical lowland (g4), South Mex/Guat/Vir IS/Ven (g5), Lesser Antilles (g6), Greater and Lesser Antilles (g7). (d) sub-structure analysis for G3 that identified nine sub-clusters: Bolivian highlands (g8), Bolivian lowlands (g9), Columbian 1 (g10), Columbian 2 (g11), Highland Andean (g12), Ecuadorian highlands (g12), Central highlands Andean (g13), northern tropical lowlands (g15) and Moroti’ sub-cluster (g16). Proportion of ancestry cutoff offset to Q>51% for structure and sub-structure analyses. The less representative accessions in the sub-structure analyses accessions are labeled with gray shadow (51% < Q < 80%).
Table 2.
Sub-cluster composition based on sub-structure analysis for Mexico and Southern Andes (G1), Mesoamerica Lowland (G2) and the South America-Andean region (G3).
Arbitrary ancestor cutoff of 51% according to Structure.
Table 3.
Genetic diversity summary statistics based on 28 microsatellite markers (SSRs) determined for clusters assigned by structure and sub-structure analysis.
Fig 7.
Suggested maize migration routes from its center of origin in Mesoamerica based on archeological evidence, historic and anthropological studies, and genetic relationships.
Red arrows indicate early maize dispersal from its origin center in Mesoamerica towards northern Mexico and Central America; dashed orange arrows represents the likely Pacific Ocean routes via maritime technologies in Pre-Columbian times; green arrows show maize migrations from the mainland to the Caribbean; light green arrows show routes followed by the Caribbean communities along the eastern coast and rivers; blue arrows correspond to movements in the Andean region in different directions. Ovals correspond to important zones of maize germplasm interchange.