Local drivers of the structure of a tropical bird-seed dispersal network
One of the major challenges in ecology is to understand the relative importance of neutral- and niche-based processes structuring species interactions within communities. The concept of neutral-based processes posits that network structure is a result of interactions between species based on their abundance. On the other hand, niche-based processes presume that network structure is shaped by constraints to interactions. Here, we evaluated the relative importance of neutral-based process, represented by species’ abundance (A) and fruit production (F) models, and niche-based process, represented by spatial overlap (S), temporal overlap (T) and morphological barrier (M) models, in shaping the structure of a bird-seed dispersal network from the Brazilian Atlantic Forest. We evaluated the ability of each model, singly or in combination, to predict the general structure [represented by connectance, nestedness (NODF), weight nestedness (WNODF), interaction evenness and complementary specialization] and microstructure of the network (i.e., the frequency of pairwise interactions). Only nestedness (both NODF and WNODF) was predicted by at least one model. NODF and WNODF were predicted by a neutral-based process (A), by a combination of niche-based processes (ST and STM) and by both neutral- and niche-based processes (AM). NODF was also predicted by F and FM model. Regarding microstructure, temporal overlap (T) was the most parsimonious model able to predict it. Our findings reveal that a combination of neutral- and niche-based processes is a good predictor of the general structure (NODF and WNODF) of the bird-seed dispersal network and a niche-based process is the best predictor of the network’s microstructure.
KeywordsAtlantic forest Forbidden links Frugivory Mutualistic network Neutrality
We thank Fundação Grupo Boticário de Proteção à Natureza (FGBPN) and Sociedade de Pesquisa em Vida Selvagem e Educação Ambiental (SPVS) for field work research permission at RNSM and RNSI; Mater Natura - Instituto de Estudos Ambientais, especially Helena Zarantonieli and Paulo Pizzi, for administrative support; Marcia Malanotte, for help with the field work and Thais B. Zanata for comments on an earlier version of the paper.
Author contribution statement
TMS, RPC and IGV conceived the ideas and designed methodology; TMS and RPC collected the data; TMS analyzed the data and led the writing of the manuscript with support from MD and IGV. All authors contributed critically to the drafts and gave final approval for publication.
This project was funded by Fundação Grupo Boticário de Proteção à Natureza (FGBPN, project number: 0875); CAPES (scholarships to TM-de-S and RPC and BEX Grant 8971/11-0 to IGV) and CNPq (PQ scholarship 309453/2013-5 to IGV). This study is part of the PhD dissertation of TM-de-S at the Pós-Graduação em Ecologia e Conservação, Universidade Federal do Paraná.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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