Global and regional ecological boundaries explain abrupt spatial discontinuities in avian frugivory interactions

Abstract

Species interactions can propagate disturbances across space via direct and indirect effects, potentially connecting species at a global scale. However, ecological and biogeographic boundaries may mitigate this spread by demarcating the limits of ecological networks. We tested whether large-scale ecological boundaries (ecoregions and biomes) and human disturbance gradients increase dissimilarity among plant-frugivore networks, while accounting for background spatial and elevational gradients and differences in network sampling. We assessed network dissimilarity patterns over a broad spatial scale, using 196 quantitative avian frugivory networks (encompassing 1496 plant and 1004 bird species) distributed across 67 ecoregions, 11 biomes, and 6 continents. We show that dissimilarities in species and interaction composition, but not network structure, are greater across ecoregion and biome boundaries and along different levels of human disturbance. Our findings indicate that biogeographic boundaries delineate the world’s biodiversity of interactions and likely contribute to mitigating the propagation of disturbances at large spatial scales.

Patterns of regional site index across a North American boreal forest gradient

“…There are inherent limitations in these regional SI models that generalize forest growth across ecoregion extents. While the boundaries likely do not impose undue error on our methods, as plant vegetation adheres to sharp polygon boundaries, thus supporting ecoregionalization as a useful technique for summarizing vegetation properties (Smith et al 2018, Martins et al 2022, there remains a significant loss of understanding of vegetation patterns on the landscape. Still, the results capture growth dynamics within areas of similar biogeography and climate, and reproduce a gradient of growth that is consistent with widely recognized forest structure and environmental gradients in the North American boreal domain (Brandt 2009).…”

“…The boundaries used for the ecoregion designations come from a widely used ecoregion product (Olson et al 2001). Studies show that plant vegetation adheres to sharp polygon boundaries, demonstrating the utility of ecoregionalization for summarizing vegetation properties (Smith et al 2018, Martins et al 2022. Many studies use a similar ecoregion approach for environmental stratification of LiDAR data (Bolton et al 2013, Neigh et al 2013, Hansen et al 2014, Margolis et al 2015.…”

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

“…The Neotropical region accounts for about half of our compiled networks, and continental areas are better covered than islands or coastal areas. It also known that species within the same biogeographical region tend to interact more and that strong species turnover between seed-dispersal networks occurs between biogeographical regions (Martins et al, 2022). Moreover, within the same biogeographical region, birds with medium to large body size or flexible diets tend to have greater range sizes due to the ability of crossing potential dispersal barriers (Claramunt et al, 2022).…”

Graph embedding and transfer learning can help predict potential species interaction networks despite data limitations

“…', the answer to which would dictate the spatial span to embed/predict. Recent results by Martins et al (2022)…”

“…In fact, we do not have a satisfying answer to the question of ‘where does an ecological network stop?’, the answer to which would dictate the spatial span to embed/predict. Recent results by Martins et al (2022) suggested that networks are shaped within eco‐regions, with abrupt structural transitions from an eco‐region to the next. Should this trend hold generally, this would provide an ecologically relevant scale at which metawebs can be downscaled and predicted.…”