Inacurácia em espécies distílicas de Rubiaceae

Abstract

Angiosperms have largely evolved very specialized reproductive strategies to benefit from efficient cross-pollination and cross-fertilization. The Heterostyly is a floral polymorphism that involves female and male reproductive structures in reciprocal position in distinct floral morphs, been seen as a mechanism that promotes cross-pollination in plant species. However, environmental factors can affect the pollination system causing variations and the breakdown of the polymorphism. Variations in the reproductive structures position affect the reciprocity level between morphs, the dispersion of legitimate pollen, and the reproductive success of the species. The heterostylous plants are represented in 28 Angiosperms and the Rubiaceae have the larger number of distyly groups among the flowering plants. The objective of the study was to investigate morphological variations in populations of distylous species of Rubiaceae using the inaccuracy index and understand patterns and factors that influence imprecision at the population and intra-individual level. To understand the variation at the population level, information of the inaccuracy in species of Rubiaceae were compiled and the factors that affected these values were tested. In addition, it was observed the intra-individual variation in some Rubiaceae species of the Cerrado, to understand the variation within the individual as an important component of for the evolution of population variation. The study pointed out patterns and trends in distylous plants based on a wide sampling of populations. In chapter one, we found that the inaccuracy of organs of both morphs was positively related among then. On the other hand, maladaptive bias (mean departure from optimum) of high and low organs were positively related to each other. We point out the maladaptive bias on low organs and thrum stigma as the main contributors to total inaccuracy. We demonstrate that corolla size is the only factor influencing inaccuracy on reproductive organs of both morphs. In the second chapter, we observed that the intra-individual variation occurs mainly in the low organs size and height of stigma of thrum morphs. Therefore, we suggest that the imprecision may vary differently at the flower level and this may be related to the different effectiveness of each sexual organ in each morph and the different selective pressures conditioning such imprecision.