Changes in temperature alter competitive interactions and overall structure of fig wasp communities

1.     Organisms exist within ecological networks, connected through interactions such as parasitism, predation and mutualism which can modify their abundance and distribution within habitat patches. Differential species responses make it hard to predict the influence of climate change at the community scale. Understanding the interplay between climate and biotic interactions can improve our predictions of how ecosystems will respond to current global warming.

2.     We aim to understand how climate affects the multi-trophic biotic interactions as well as the community structure using the enclosed communities of wasps associated with figs as a study system.

3.     To examine the presence and strength of multi-trophic species interactions, we first characterized the multi-trophic community of fig wasps associated with Ficus racemosa and then applied hierarchical joint species distribution models, fitted to community monitoring data. We further evaluated the effect of climate on individual species trends as well as inter-specific interactions.

4.     We found that the competitive balance shifted to favour non-pollinating galling wasps and disadvantage the dominant pollinator in sub-optimal conditions. Further, sub-optimal conditions for galling wasps facilitated the occurrence of their specialized parasitoid, as changes cascaded across trophic levels and led to alternative community structures. Our results highlight the role of how species interactions can be modified across multiple trophic levels in a fig wasp community according to climate.

Methods
Fig wasps species abundance and composition based on long-term monitoring.