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

South America presents much more diversity in relation to habitats, people, and culture than Mesoamerica. For instance, maize arrived in South America, but apparently the level of consumption seen in Mesoamerica/Central America was rarely found there. Archaeological data indicate that only during the implantation and expansion of the Inca Empire (800-500 YBP) was the level of maize consumption important, but the level of consumption was not comparable to that of Mesoamerica/Central America [71] [72] [73] . Additionally, South Amerindian hunter-gatherers/foragers present lower intrapopulation genetic variation and higher levels of population structure when compared to those seen in Andean populations [27, 74] . This same tendency was also observed in the present study. These results indicate low levels of gene flow between villages/populations and low effective population sizes, favoring the role of genetic drift. Conversely, the Andean groups show opposing characteristics. These findings correlate well with distinguishing patterns of gene flow and historical effective sizes in these indigenous populations, with cultural differences, as well as with paleoclimatic and environment changes in their habitats [74] . Therefore, the significant role of random processes and/or more heterogeneous cultural and ecological scenarios makes it difficult to define a particular pattern associated with the Arg230Cys polymorphism in South American groups, a situation different from that in Mesoamerica.