Análise espacial e temporal dos caracteres florais e do sistema de polinização em populações de Calathea altissima (Poepp. & Endl.) Korn. (Marantaceae) ao longo de um gradiente longitudinal na Bacia Amazônica

Abstract

Plant-pollinator interactions have been used extensively as model systems to explore basic aspects of evolution. A common idea accepted in the study of pollination is that plants tend to specialize in certain pollinators species, and possibly the contrary also occurs. Two fundamental principles have been guiding the understanding of the evolution of specific plant-pollinator interactions: the pollination syndromes concept, which constitute categories of floral traits and resources associated with the attraction of specialized pollinators, and the most important pollinator principle that establishes that plants can be pollinated by different pollinator species, but that in fact only the most important pollinator agent would be responsible for influencing the evolution of floral traits. Parallel to the growing scientific interest in the level of specialization/generalization of plant-pollinator interactions, there is the empirical observation that such interactions undergo a considerable spatial and/or temporal variation effect. The pollinators of a given species may vary among different populations, creating a regime of divergent selective pressure along the distribution area of the species, leading to the emergence of a geographic mosaic of coevolution. With the spatial and/or temporal variation of pollinators, that can be an important factor in the emergence of geographical variations in floral traits through local adaptations, and the study of these systems may help in a better understanding of the mechanisms promoting speciation and evolution. According to the theoretical basis presented, the main objective of this study was to investigate the pollination system of Calathea altissima (Marantaceae) in three regions along a longitudinal gradient 500 km apart in the Brazilian Amazon. We explored the following questions: (1) Is there a spatial variation in the floral characteristics of C. altissima among the studied regions? (2) Is there a spatial and/or temporal variation in the pollination system of the species among populations and/or regions of the study? The geographic analysis of the pollination system revealed the absence of spatial variation of floral traits and absence of spatial and temporal variation of pollinator agents, indicating that the level of specialization of C. altissima in relation to Euglossini bees would be a characteristic of the species and not a variable characteristic between populations.