Efeitos ecológicos e evolutivos nos padrões de diversidade de aves na Amazônia

Abstract

Studies covering phylogenetic and functional diversity have been increasingly used to explain patterns of species diversity and organization of biological assemblages, constituting complementary tools to the traditional taxonomic approach (e.g. species richness). Biogeographical knowledge may also contribute to the understanding of these patterns, since the geographical distribution of different taxa depends on historical processes related to dispersion and speciation, in this manner influencing the formation of regional pools of species. In this thesis we evaluated the influence of historical processes and environmental factors on the diversity of Amazon bird assemblages. We compiled compositional data from 80 bird assemblages, 12 in savannas and 68 in terra firme forests, totaling 878 species. In Chapter 1 we evaluated the phylogenetic and functional diversity of passerine birds (Passeriformes order) considering two factors: the biogeographical history of each suborder (Passeri and Tyranni) and the habitat type (forest and savanna). We verified the importance of the different habitats for the maintenance of bird diversity since, although Amazonian savannas present low species richness when compared to forests, this habitat presents assemblages with unique combinations of ecological traits and specific lineages. We showed through the results found in this chapter that the greater functional diversity of Passeri assemblages in both habitats and the greater phylogenetic diversity of Tyranni in terra firme forests are related to the biogeographic history of each suborder and their adaptation to the habitat. In Chapter 2, we assessed the contribution of Amazonian biogeographic regions (a.k.a., endemism areas) and climatic variables to species composition and to the phylogenetic structure of canopy and forest understory bird assemblages. We hypothesized that differences in species composition are greater between interfluves for understory bird assemblages, which are composed of species with lower dispersion capacity, than for canopy birds. In this chapter, we found that the understory bird assemblages were more influenced by biogeographic barriers than canopy birds, corroborating our hypothesis. The climatic variables were important to explain the species diversity and phylogenetic structure of both groups. With the results generated in this thesis I concluded that the Amazonian bird diversity is result of processes related to biogeographic history, ecological traits of species, and environmental conditions.