Abstract:

Aims: Species-resource utilization networks can illustrate the competition, sharing, and differentiation among different species in resource utilization, providing a novel perspective on understanding species diversity within communities. Insect communities are influenced by both the resource utilization patterns of species within the community and the ecological traits of host plants. Explaining species-resource utilization network metrics in the context of host ecological traits will help reveal the organization and factors that determine species diversity in insect communities.
Methods: In this study, we collected fig wasp communities from 18 Ficus species. Subsequently, we built fig wasp-fig fruit resource utilization networks for each Ficus species, examined the correlations between network metrics, and assessed how various host characteristics (such as pollination type, life form, and breeding system) affected these network metrics.
Results: From the 18 Ficus species, we collected 173 species of fig wasps belonging to 28 genera and 5 different families. The species number of fig wasp community was negatively correlated with connectance of the fig wasp-fig resource utilization networks and positively correlated with C score (a measure of resource utility differentiation). Robustness did not significantly correlation with species number, but it showed a positive correlation with connectence, WNODF (weighted nestedness metric based on overlap and decreasing fill), Shannon diversity for interaction, and distribution overlap. It was, however, significantly negatively correlated with specialization and C score. When compared to dioecious fig trees, monoecious fig trees exhibited a higher level of specialization, lower distribution overlap, and greater C score. Meanwhile, monoecious fig trees hosted more fig wasp species than dioecious fig trees.
Conclusion: All of these findings suggest that the specialization and differentiation (as indicated by the C score) in resource utilization among fig wasps enhance the richness of species within the community. This underscores the essential role of interspecific competition for resources in driving diversification among closely related species. Robustness to resource loss of community is not linked to species richness but is instead correlated with the extent of species coexistence, denoted by connectence and distribution overlap. Additionally, the breeding system also plays a role in the diversification of fig wasps, possibly by restricting the oviposition of non-pollinating fig wasps.

Key words: species-resource network, insect-plant interaction network, network metrics, insect diversity, fig wasp community