História evolutiva das árvores de cuia (Crescentia cujete): uma integração entre genótipo, ambiente e cultura

Abstract

Amazonia is a center of plant domestication, where high linguistic diversity, different artistic styles and subsistence strategies also developed. The role of humans in the geographical distribution of Amazonian biodiversity, and the different pressures they exerted in the life history of organisms are debated. The historical analyses of the use of a plant across its geographical distribution contributes to this debate, since it aims to identify the morphological and genetic modifications promoted by human activity, identify areas of biological and cultural diversity, as well as understand the factors that influence the dynamics of the use and management of plant varieties. In this context, the general objective of this thesis was to contribute to the reconstruction of the domestication history, dispersal and diversification of treegourds (Crescentia cujete, Bignoniaceae) in Brazilian Amazonia. The fruits (cuia) have symbolic and technological values for different native peoples across the Neotropics, and therefore, are good examples for the integration of the social and cultural aspects of the biology of domestication. From a genomic library of C. cujete, molecular markers were developed, which were the basis to analyze the genetic relationship between C. cujete and C. amazonica in the Amazon Basin and test Gentry’s (1980) and Ducke’s (1946) hypotheses about the origin of domestication and morphological diversification of treegourd fruits. The evaluation of how people perceive, use and propagate fruits of both species integrated with genetic, morphological and ethnobotanical analyses between Amazonia and Mesoamerica allowed discussion of alternative hypothesis of the origin of domestication, infer routes of the plant dispersal, and identify cultural and ecological factors of selection and diversification. The results showed that hybridization is important for the phenotypic diversity of the fruit. Local varieties (maracá, cuiupi, paranã) are intimately associated with gene flow between homegardens and flooded forests, and their specific uses suggest that management of hybridization is an ancient practice in Amazonia. It was demonstrated that domesticated C. cujete was introduced into the Amazon Basin and into Mexico, but its geographical origin of domestication remains unknown. The pattern of genetic diversification between Western and Eastern Amazonia allowed inferences of two routes of introduction. These agree with routes previously proposed for human groups and their plants. Mesoamerica and Amazonia have contrasting fruit morphological diversity, which suggests different cultural preferences along treegourd’s dispersal routes. Even after the demographic collapse of human populations and their plants caused by European conquest, fruit shapes and fruit sizes manipulated by modern Native Amazonians and riverine families are legacies of the pre-Columbian occupation in Amazonia.