DOI: 10.5061/dryad.gmsbcc2hv
title: Data from: Seed-dispersal networks in tropical forest fragments: area effects, remnant species, and interaction diversity

description: Seed dispersal interactions involve key ecological processes in tropical
 forests that help to maintain ecosystem functioning. Yet this
 functionality may be threatened by increasing habitat loss, defaunation
 and fragmentation. However, generalist species, and their interactions,
 can benefit from the habitat change caused by human disturbance while more
 specialized interactions mostly disappear. Therefore changes in the
 structure of the local, within fragment, networks can be expected. Here we
 investigated how the structure of seed-dispersal networks changes along a
 gradient of increasing habitat fragmentation. We analysed 16 bird
 seed-dispersal assemblages from forest fragments of a biodiversity-rich
 ecosystem. We found significant species-, interaction- and network-area
 relationships, yet the later was determined by the number of species
 remaining in each community.  The number of frugivorous bird and
 plant species, their interactions, and the number of links per species
 decreases as area is lost in the fragmented landscape. In contrast,
 network nestedness has a negative relationship with fragment area,
 suggesting an increasing generalization of the network structure in the
 gradient of fragmentation. Network specialization was not significantly
 affected by area, indicating that some network properties may be invariant
 to disturbance. Still, the local extinction of partner species, paralleled
 by a loss of interactions and specialist-specialist bird-plant seed
 dispersal associations suggests the functional homogenization of the
 system as area is lost. Our study provides empirical evidence for
 network-area relationships driven by the presence/absence of remnant
 species and the interactions they perform.
description: We compiled 16 studies of avian plant-frugivore interactions
 sampled at the community level along the Atlantic Forest biome, a hotspot
 of biodiversity highly threaten by increasing human pressure (Ribeiro et
 al. 2009, Joly et al. 2014; Fig. 1, Table S1). The study areas varied from
 0.66 to 42,000 ha, along a gradient of disturbance from semi-pristine
 Biological Reserves and State Parks to secondary forest fragments and
 restored private lands. The matrix surrounding the fragments is variable,
 including sugar cane fields, crop plantations, secondary forest, and urban
 areas.
description: Overall the studies included here originally aimed to record
 bird-eating-fruit interactions and not necessarily effective seed
 dispersal; therefore we carefully checked every dataset and removed any
 interaction that would not characterize plant dispersal events, such as
 seed predation. In the particular case of parrots we excluded them from
 the analysis despite some rare evidences pointing to their role in
 effective seed dispersal of large nuts (Tella <i>et al.
 </i>2016); in most cases we could not establish in the original
 papers whether the frequency of interactions involving parrots actually
 implied legitimate dispersal. We updated and standardized plant and bird
 species names using the taxize package (Chamberlain & Szocs, 2013)
 in R (R Development Core Team 2014).