Species-level drivers of avian centrality within seed-dispersal networks across different levels of organization

Abstract

Bird-plant seed-dispersal networks are structural components of ecosystems and have been used to assess species’ functional roles. The role that bird species play in seed-dispersal networks (from less connected [peripheral] to more connected [central]), determine the interaction patterns and their ecosystem services. These roles may be determined by drivers related to morphological and functional traits, evolutionary properties, geography, and environmental conditions acting at different spatial and temporal scales. However, it is still unknown if such drivers are equally important in determining species centrality at different network levels, from individual local networks to the global meta-network representing interactions across all local networks. Here, using a dataset of 314 local networks covering five continents and eleven biogeographic regions, we show that drivers related to geography are more important in explaining species centrality in the meta-network, but these drivers were not as important in local networks. At the global meta-network level, we found that species’ range size was the most important driver with more central species having larger range sizes, which would facilitate the interaction with a higher number of plant species and thus the maintenance of seed-dispersal interaction patterns at the global scale. Morphological traits such as beak width, body mass, and wing length had secondary explanatory power. At the local network level, none of the tested drivers of centrality had significant effects, perhaps because local factors related to resource availability are more important at this scale. Taken together, our results show that the drivers determining species centrality are scale dependent, suggesting that prediction and protection of species functional roles in seed-dispersal interactions requires a combined local and global approach.

Species‐level drivers of avian centrality within seed‐dispersal networks across different levels of organisation

“…Data available from the FigShare Digital Repository https://figsh are. com/s/6d409 efbed 4f9d0 c239e (Moulatlet et al, 2023).…”

Moving towards a comprehensive view of the spatial processes in seed dispersal networks: Embracing metacommunities

“…Most of interaction patterns in seed dispersal systems have been assessed for local assemblages; however, growing data sets available on this kind of interaction has recently allowed for the construction of large‐scale meta‐networks that combine all the locally observed interactions in one single network (Emer et al, 2018; Fricke & Svenning, 2020; Vizentin‐Bugoni et al, 2021). Moulatlet et al (2023) contribute to this cross‐scale approach by moving from local networks to a broader spatial scale, one global meta‐network, when investigating the importance of different properties and traits as drivers of bird species centrality in seed dispersal networks (Figure 1). The authors assessed the role of morphological, geographical, climatic and evolutionary properties as predictors of species centrality and, following their expectations, the factors determining centrality were different between spatial scales.…”

“…Spatial scale affects the ecological drivers of node‐level attributes in seed dispersal networks. Bird species centrality at local scale may respond to morphological traits such as body mass, whereas at the global scale, centrality may be more related to geographical factors, such as range size (Moulatlet et al, 2023). An intermediate level of analysis, that of metacommunities, may contribute to a better understanding of the interplay between local and spatial processes, both operating at broad biogeographic realms, while shaping ecological networks.…”

“…Focusing on node‐level descriptors, Moulatlet et al (2023) showed the effects of spatial scale on the predictors of bird species centrality in seed dispersal networks (Figure 1). However, we still need to further investigate how the spatial scale of observation affects the overall structure of ecological networks, a relevant topic if we are to understand the implications of the current biodiversity crisis on the persistence and functioning of ecological systems (Galiana et al, 2018).…”

“…Therefore, given the key role of dispersal in this approach, metacommunities can be defined at an intermediate scale of analysis, above the level of local communities and below the level of large‐scale biogeographic studies (Chase & Bengtsson, 2009). In this perspective, the work of Moulatlet et al (2023) sheds light on processes operating at the local and global spatial scales. Future efforts to include one more spatial scale (i.e.…”