Navegando por Autor "ALMEIDA, Sara Miranda"

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Acesso aberto (Open Access)
Efeitos ecológicos e evolutivos nos padrões de diversidade de aves na Amazônia
(Universidade Federal do Pará, 2018-09-20) ALMEIDA, Sara Miranda; SANTOS, Marcos Pérsio Dantas; http://lattes.cnpq.br/7941154223198901
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.
Acesso aberto (Open Access)
Environmental structure affects taxonomic diversity but not functional structure of understory birds in the southwestern Brazilian Amazon
(Instituto Nacional de Pesquisas da Amazônia, 2019-09) OLIVEIRA, Jocieli de; ALMEIDA, Sara Miranda; FLORÊNCIO, Fernando do Prado; PINHO, João Batista de; OLIVEIRA, Dalci Mauricio Miranda de; SANTOS, Raphael Ligeiro Barroso; RODRIGUES, Domingos de Jesus
Changes in environmental characteristics can affect habitat use by birds, impacting the number of individuals, number of species, and changing species composition and functional structure of assemblages. Metrics that evaluate the functional structure of biological assemblages constitute a complementary tool to the traditional taxonomic approach, because they quantify the differences between species by means of functional traits. We assessed the effect of environmental characteristics on the taxonomic diversity (species richness, species composition and number of individuals) and functional structure (functional richness, functional evenness, Rao’s functional diversity, and community-weighted mean traits) of bird assemblages in northern Mato Grosso state, in the southwestern Brazilian Amazon. We sampled birds in 32 plots. At each plot birds were captured using mist nets, and eight environmental variables were measured: canopy openness, leaf litter, elevation, number of trees in three classes of DBH, soil clay content, and distance to nearest stream. To evaluate functional structure, we measured seven morphological traits from individuals of each bird species. Habitat variables had a significant effect on taxonomic diversity. However, the general functional structure was not affected. Elevation and distance to nearest stream were the main variables driving changes in taxonomic diversity and had a minor effect on functional richness. The other metrics of functional structure were not significantly affected by the set of environmental variables. Our results suggest that the sampled bird assemblages exhibit some functional tolerance (redundancy) to small-scale environmental variation, implying certain resilience to ecosystem modification.