DOI: 10.5061/dryad.dbrv15f4w
title: Habitat loss shapes the structure and species roles in tropical plant-frugivore networks

description: Habitat loss is a global threat to biodiversity with pervasive effects on
 species and populations. These impacts may generate cascading effects on
 ecological processes propagating across ecological networks. Thus,
 understanding how habitat loss affects ecological networks is fundamental
 for conservation. We used a database of 25 plant-frugivore networks
 distributed across the whole Brazilian Atlantic Forest to understand how
 landscape-scale habitat loss shapes network structure, robustness, species
 role and traits related to seed dispersal. We compared whether these
 network properties have linear or non-linear relationships and used
 centrality metrics and indirect effects to evaluate if habitat loss change
 the role of species in plant-frugivore networks. We found linear and
 non-linear relationships with negative effects of habitat loss on the
 network structure. As a consequence of shifts in species richness and
 number of links, the number of interactions and the proportion of possible
 interactions observed (connectance) were negatively associated with
 habitat loss. In contrast, nestedness increased with habitat loss. Network
 robustness, mean bill width and mean seed size were not significantly
 related to habitat loss. In addition to changes in interaction patterns at
 network level, habitat loss also favors changes in interaction among
 species, shifting the species playing central roles in network
 organization or contributing to indirect effects in the networks. In
 forested landscapes, obligate frugivores are the main central species in
 the network, and the ones potentially contributing to indirect effects,
 while in deforested landscapes these roles are fulfilled by occasional
 frugivores. Thus, our results emphasize the widespread effect of habitat
 loss on plant-frugivore systems, adding evidence that its pervasive
 effects on biodiversity also proliferate on mutualistic interactions with
 negative consequences for seed dispersal that potentially go beyond the
 direct pairs of interacting species. 
description: We gathered information from published
 studies on frugivory networks in the Brazilian Atlantic Forest. This
 biodiversity hotspot has suffered from intense deforestation, and
 currently less than 30% of its forest still remains (Rezende et al. 2018,
 Galetti et al. 2021). The Atlantic Forest is considered a hotspot of
 biodiversity in the world due to the high diversity, levels of endemism
 and the presence of threatened species (Myers et al. 2000). In the
 Atlantic Rainforest, seed dispersal by animals is mainly performed by a
 diverse assemblage of bird species, especially in areas in which large
 mammals died out due to multiple forms of human impact. In this paper, we
 have focused in the seed dispersal by birds. Data on plant-bird networks were obtained in
 the largest published database on interactions available for the Brazilian
 Atlantic Forest, the ATLANTIC FRUGIVORY (Bello et al. 2017). This database
 compiled more than 8000 frugivory interactions from 331 vertebrates and
 788 plant species recorded in 166 studies. From the database we selected
 only network studies focusing on birds. Our dataset includes only
 community-level studies (i.e., those that recorded the interactions
 between bird and plant assemblages in a forest fragment, using different
 methodologies such as focal observations, feeding bouts, etc). Thus, we
 excluded from the database studies focusing on plant or animal
 populations. We completed the data searching for additional studies on
 plant-bird interactions in the Web of Science and Scopus using the
 following search terms: ("ecological network*" OR
 "mutualistic network*" OR "frugivor*") AND
 ("bird*") AND (“Atlantic Forest”) in TOPIC. From this search, we
 included only network studies that have the coordinates of the sampling
 fragment and provided the matrix of interactions. Our final database is
 composed of 25 qualitative plant-bird frugivory networks from different
 forest fragments, 12 from the ATLANTIC FRUGIVORY and 13 from the
 literature search.