Abstract:

Plant–pollinator interaction networks are dynamic entities, and seasonal variation in plant phenology can reshape their structure on both short and long timescales. However, such seasonal dynamics are rarely considered, especially for oceanic island pollination networks. Here, we assess changes in the temporal dynamics of plant–pollinator interactions in response to seasonal variation in floral resource richness in oceanic island communities.

We evaluated seasonal variations of pollination networks in the Yongxing Island community. Four temporal qualitative pollination networks were analyzed using plant–pollinator interaction data of the four seasons. We collected data on plant–pollinator interactions during two consecutive months in each of the four seasons. Four network-level indices were calculated to characterize the overall structure of the networks. Statistical analyses of community dissimilarity were used to compare this community across four seasons to explore the underlying factors driving these patterns. We also evaluated the temporal variation in two species-level indices of plant and pollinator functional groups.

Both network-level specialization and modularity showed a significantly opposite trend compared with plant species richness across four seasons. Increased numbers of plant species might promote greater competition among pollinators, leading to increased niche overlap and causing decreased specialization and modularity and vice versa. Further analyses suggested that the season-to-season turnover of interactions was dominated by interaction rewiring. Thus, the seasonal changes in niche overlap among pollinators lead to interaction rewiring, which drives interaction turnover in this community. Hawkmoths had higher values of specialization and Apidae had higher values of species strength compared with other pollinator functional groups. These findings should be considered when exploring plant–pollinator interactions in ecosystems of isolated oceanic islands and in other ecosystems.

Key words: interaction rewiring, modularity, oceanic island, pollination networks, seasonality, specialization, species strength