Aspectos ecológicos e genéticos da domesticação de populações de Pourouma cecropiifolia Mart. da Amazônia Ocidental

Abstract

The study of the different aspects, morphological, ecological and genetic that mark the changes generated with human selection, provides integrated and robust information about the plant domestication history. The objectives of this study were: i) identify the magnitude of the differences between the domesticated populations of Pourouma cecropiifolia and the wild populations located in adjacent forests; ii) evaluate whether human selection altered fruits and seeds allometric relationships in domesticated plants of Pourouma cecropiifolia; iii) investigateif there is a relation between the morphological characteristics of Pourouma cecropiifolia and variations in the environmental conditions and whether this relationship differs between domesticated and wild populations; iv) quantify the difference in genetic diversity between the wild and domesticated populations of Pourouma cecropiifolia and v) identify the Pourouma cecropiifolia domestication origin center based on chloroplastidial diversity. To answer the study questions, we compared the fruits and seeds morphological characteristics between wild and domesticated populations to quantify the direct effects of domestication. To understand the correlated effect between human selection and natural selection, we quantify the differences in the characteristics of the whole plant, evaluated the effects of artificial selection on the fruits and seeds allometry, and investigate the relation of the characteristics with the environmental conditions. To evaluate the domestication genetic effects, we quantified the diversity and genetic differentiation between the wild and domesticated groups of Pourouma cecropiifolia using chloroplast DNA sequences. In the domesticated plants, the fruits had double edible pulp and 20x greater mass than the wild plants fruits. The values of plant height: DBH ratio and wood density were, respectively, 42.15% and 21.74% higher in the wild populations. The domesticated populations showed greater morphological variability in characteristics under direct selection: size and mass of fruits, seeds and pulp. The combined action of natural selection and human selection modified the expected pattern in the allometry between seed mass and fruit mass, due to the contrasting effects between environmental filters, which promote seed reduction and human selection, which promotes the seed increase. Environmental variations did not have a significant effect when compared to the effects of human selection on the morphological changes associated with domestication. The domesticated populations were 32% less diverse than wild populations. The relation between the lineages suggests that the domestication of Pourouma cecropiifolia originated in Alto Solimões.