A importância das interações bióticas e atributos na distribuição das espécies e estruturação das comunidades ecológicas

Abstract

Structural and climatic disturbances created directly or indirectly by human activity have a profound effect on organisms and are responsible for the increasing changes in biodiversity. Such changes are associated with relevant modification in the relative abundance, extinction and invasive ability of the species. In this context of imminent changes, there is an increasingly urgent need to describe patterns and understand processes that govern biodiversity, in order to predict and mitigate current and future changes. One way of doing this is through species distribution models, which are generally built only with abiotic predictors since the importance of biotic interactions is considered irrelevant at large spatial scales (Eltonian noise hypothesis). To test the Eltonian noise hypothesis, we modeled the distribution of several species of hummingbirds distributed across the American continent and evaluated the effect of biotic interactions on model performance and spatial predictions (Chapter 1). We found that the addition of biotic interactions had little effect on model performance and predicted environmental suitability, but altered the estimated geographic distribution of the species. This spatial dissimilarity did not improve the model, what suggests that species distribution models might be sensitive to the inclusion of predictor variables, especially in large spatial extents. Moreover, in order to understand the processes that govern the assembly and maintenance of communities, we investigated the role of resource partition for species coexistence. Specifically, we evaluated which traits associated with the acquisition of trophic resources can explain the coexistence of similar species in the communities (Chapter 2). We conclude that communities with more overlapping species are, in fact, partitioned on a fine scale, associated with the species' foraging behavior. Finally, knowing that information about species are essential for biodiversity studies, we propose to assess the size and the sources of the Raunkiaeran shortfall of birds (Chapter 3). We show that the knowledge gap on the investigated traits is large mainly for small-ranged species from tropical regions, but we also show that data sharing and mobilization can significantly expand our current knowledge.