Evolução, gradientes ambientais e nicho trófico larval como determinantes para padrões de diversidade de borboletas frugívoras na Amazônia

Abstract

Organismal spatial occupancy in Earth ecosystems results from evolutionary and ecological events. Species distribution reflects adaptation, mediated by their intrinsic attributes, to internal physiological demands and filters imposed by the surrounding environment. To study such patterns, community ecology has been associating strictly taxonomic approaches to start incorporating information on functional traits and phylogenetic relatedness of species. This method is particularly important when studying diverse landscapes and organisms, such as the Amazon rainforest and butterflies. In this thesis, we investigated (1) the evolutionary correlation between flight morphology, vertical stratification and sexual dimorphism of fruit-feeding butterflies, (2) the spatial variation in taxonomic, functional and phylogenetic diversity patterns of butterflies across an Amazonian vegetation mosaic and (3) the role of juvenile trophic niche on the spatial occurrence of adult butterflies across local and regional Amazon gradients. We sampled butterflies with bait traps in seven localities across three Brazilian states. For the first chapter, we used Phylogenetic Generalized Least Squares models, whereas for the remaining two chapters we ran multiple regressions (II) and linear mixed effects models (III). In chapter one, we found that variation in flight morphology may be explained by vertical stratification and that such association is stronger in females. Additionally, there is a sharp sexual dimorphism in flight morphology, especially among understorey-dwelling species. In chapter two, we demonstrated that highly illuminated white-sand forests harbour higher abundance, but lower species richness of fruit-feeding butterflies. These species tended to be larger, stronger flying and more generalist during larval stage. In ombrophilous forests, larvae are more specialized, possibly due to a greater availability of ecological niches. In chapter three, we verified that larval dietary niche is determinant for the spatial occurrence of adult butterflies. It however does not act as mediator for the influence of vegetation complexity, geographic position and biogeography on taxonomic and phylogenetic diversity patterns. Therefore, we conclude that Amazonian heterogeneity from local microhabitats to regional landscapes is imperative for maintaining the diversity patterns of frugivorous butterflies. At the microhabitat scale, the removal of the vertical stratification will result in the loss of species associated with particular strata, whose flight morphology is intimately connected to environmental physical conditions. At the local scale, white-sand phytophysiognomies harbour butterfly communities that are taxonomically and functionally unique, thus being irreplaceable for maintaining the diversity of these insects. At the regional scale, we detected diversity patterns likely driven by dispersion, historical colonization and biogeographical events. These three scales interact, ultimately determining the spatial distribution of organisms as we currently see. We hope our results will help strengthen the establishment of appropriate land use planning and the selection of conservation priority areas.