Data from: From species lists to interactions: Network structure, not richness, guides seed dispersal management in human-modified islands

Seed dispersal by animals supports plant regeneration and ecosystem
resilience, yet conservation success is still commonly evaluated using
species richness rather than the organisation of ecological interactions.
This is particularly problematic in human-modified ecosystems, where
management interventions can increase diversity without restoring
historical interaction structures or functional stability. We compared
seed dispersal networks on two climatically and biogeographically similar
oceanic islands in the Seychelles archipelago with contrasting management
trajectories: one strictly protected and under historically oriented
management, aimed at limiting introductions and maintaining historically
informed community structure, and one anthropogenically diversified
through long-term human occupation and species introductions. Using a
multi-metric ecological network approach integrating modularity-based
roles, centrality indices and motif analyses, we quantified how plants and
dispersers contribute to network structure under each management context.
Anthropogenic diversification increased interaction diversity and the
number of dispersal events but resulted in a less cohesive network
dominated by peripheral species and a narrow set of structurally central
dispersers. In contrast, the historically oriented management island
exhibited lower interaction diversity but greater network cohesion, with
strong redundancy in plant-level dispersal pathways. Shared species
occupied different structural roles across islands, indicating strong
context dependence in their contribution to seed dispersal networks. Motif
analyses revealed contrasting interaction niche structures across
management contexts. In the anthropogenically diversified island,
dispersal relied on a small set of generalist dispersers, suggesting
potential vulnerability to their loss. In the historically oriented
management island, dispersal was spread across more species, indicating
greater redundancy. These differences imply distinct but predictable
vulnerabilities arising from alternative management pathways. Our findings
show that management strategies can create fundamentally different seed
dispersal regimes, even under similar environmental conditions.
Anthropogenic diversification reshapes network organisation into distinct
structural configurations, rather than consistently enhancing overall
cohesion. Incorporating interaction structure into conservation planning
can help prioritise key dispersers and plants, anticipate hidden
vulnerabilities, and guide management actions that better sustain seed
dispersal processes in human-modified island ecosystems.