Evolutionary Responses to a Constructed Niche: Ancient Mesoamericans as a Model of Gene-Culture Coevolution

Hünemeier, Tábita; Amorim, Carlos Eduardo Guerra; Azevedo, Soledad; Contini, Veronica; Acuña-Alonzo, Víctor; Rothhammer, Francisco; Dugoujon, Jean-Michel; Mazières, Stephane; Barrantes, Ramiro; Villarreal-Molina, María Teresa; Paixão-Côrtes, Vanessa Rodrigues; Salzano, Francisco M.; Canizales-Quinteros, Samuel; Ruiz-Linares, Andres; Bortolini, Maria Cátira

Genetic, archeological, botanical, and paleoecological data furnished evidence that maize (Zea mays ssp. mays) had a single domestication origin from the wild grass teosinte (Zea mays ssp. parviglumis) in the Río Balsas region, southwestern Mexico, approximately 6,300-10,000 calendar years before present [44] [45] [46] [47] [48] [49] [50] [51] [52] [53] . Pollen samples taken from sediments in lakes, swamps, and archeological deposits have provided evidence for the presence or absence of Zea (maize and/or teosinte) in the Americas and have been used to estimate the age of maize domestication and dispersion [44] . Blake [44] summarized the Zea pollen dates from several American archeological sites, and we selected this data set to perform our analysis. To test the connection between maize culture and the ABCA1*230Cys variant, we used allele frequencies from Mesoamerica/Central America populations (Zapotec, Maya, Nahuatl,Kaqchikel-Quiche, Totonac, Cabecar, and Guaymí) as well as Zea pollen dates obtained in archeological sites located geographically near these populations ( Table 2 ). Spearman rank order correlations between the two data sets (Zea pollen archeological records and ABCA1*230Cys allele frequencies) were obtained using the Statistica 7.0 software (StatSoft, Incß). Table 1 presents the genotype and allele frequencies for the 1905 individuals analyzed, including the new samples genotyped in the present study. A molecular analysis of variance (AMOVA) test was performed to quantify the level of population structure observed within and between the 3 subdivisions adopted here (Mesoamerican agriculturalists, Andean agriculturalists, and South American hunter-gatherer/forager; Table 1 ). A significant difference was observed between the subdivisions (F CT = 0.036; p = 0.000). On the other hand, the highest F ST among populations within subdivisions was observed in the South American huntergatherers/foragers (0.053; p = 0.005), and a value 5 times lower was found among Mesoamerican agriculturalists (0.013; p = 0.008); no sign of structuration was found in the Andes area (p = 0.36).