Interações entre aves e plantas: frugivoria, amplitude de nicho e relações morfológicas, em três diferentes ambientes

Abstract

The interaction between frugivorous birds and plants is one of the most important mutualisms in tropical regions. However, the way these groups interact varies according to temporal availability of fruit. In seasonal sites, it is expected that a specialization in a particular type of fruit is not viable, because this feature is not available throughout the year, and species that occupy these sites have a broad trophic niche. With a more stable supply of resources, a greater level of specialization is expected, which would be reflected in a narrower niche width. A relationship between the morphology of birds and type of fruit consumed can also be associated with the specialization level of diet and niche width of the birds. This relationship might possibly be more evident in local with reduced seasonality. The goal of this paper is to investigate the relationships, both ecological as morphological, between frugivorous birds and plants consumed in sites with different levels of resource seasonality. Cerrado sensu stricto were considered the most seasonal, followed by seasonal deciduous and semi-deciduous forests, which were grouped as \"seasonal forests\". Atlantic forest was seen as a site less seasonal. We tested the hypothesis that species of the guild \"frugivorous\" will be more representative of the number of species and interactions in less seasonal area, and that species of more seasonal areas would have a more generalist diet and broader trophic niche than that observed for species less seasonal site. In Chapter 2 we investigated the existence of relationships between morphology of the birds beak and size of fruits eaten by them, testing the hypothesis that this combination was more evident in local whose species exhibit lower niche amplitude than in that have species with broader niche width. In this study the community structure of each site was described and was observed narrower trophic niche for species of seasonal forests and Atlantic forest (more specialized diet) than that found for species of cerrado ss (more generalist diet). However, morphological specialization was found only in species of seasonal forests, where we observed an association between the width and depth of the tip with the size of the fruit consumed. The variation observed for specialization in diet and morphology may be related to temporal availability of resources among different sites. Furthermore, other features in the selection of fruits, behavioral traits of birds and ecological interactions with other community members also seem to influence the consumption patterns of birds.