O papel dos atributos morfofuncionais e do perfil taxonômico de aves frugívoras de sub-bosque em redes de interações mutualísticas ave-planta

Abstract

This study aims to describe the seed dispersal process in two neotropical areas, to associate the animal characteristics to network parameters, used as indicative of the importance of species to seed dispersal process, and to assess the influence of seed condition evaluation on the network structure. The two areas sampled to describe the seed dispersal process are located in Juiz de Fora – MG. Twenty-three bird species were sampled in the areas, with families Pipridae, Thraupidae, Turdidae, and Tyrannidae the most representative. The networks had a non-modular, non-nested, and non-asymmetric structure, suggesting low stability. The frugivorous and omnivorous species presented the highest values of the parameters, suggesting greater importance in the structuring of the networks. The relationship between bird characteristics and network parameters was assessed using a mixed generalized linear model, using data from 13 seed dispersal networks, which sampled feces from understory birds captured by the use of mist-nets. A significant relationship was found between the parameters normalized degree, strength and centrality of proximity and dependence on fruits, and between the normalized degree and centrality of proximity and the behavior of swallowing whole fruits. The evaluation of the seed condition was performed by the tetrazolium chloride test, producing two nets for each of the two areas studied: one network with all the seeds obtained and one with only the live seeds. The Melastomataceae family was the most representative and, at the same time, the one with the highest proportion of dead seeds. Both areas showed similar trends, with nets from live seeds showing higher values of modularity and asymmetry, and lower nesting values when compared to nets based on all seeds. Thus, it is possible to conclude that the seed dispersal process from understory birds is not very stable if studied in isolation, that species that are more dependent on fruits and that swallow them without mandibles are the most important for maintaining the stability of the process and that the evaluation of the condition of the seeds after the dispersion can be essential for a more refined understanding of the process.