Cover February 2026

A 27-year, continent-wide study of fig wasps by Souza et al. (2025) shows that communities linked to Neotropical fig trees change dramatically across space, with high species turnover —highlighting how ecological and evolutionary forces shape biodiversity in tightly linked plant–insect systems.

Photo: Jean-Yves Rasplus

Abstract: Wasp communities associated with fig trees, Ficus spp., are a model system to investigate how local and regional processes shape biodiversity across large geographical ranges. We investigated the β-diversity of fig wasp assemblages associated with three widely distributed Neotropical fig species – F. citrifolia, F. obtusifolia and F. pertusa – using 27 years of spatially extensive sampling across Brazil, Costa Rica and Ecuador. We quantified β-diversity using the Sørensen index and its components of turnover and nestedness. For all three Ficus species, β-diversity was high (0.87–0.90), driven primarily by species turnover (85–96% of β-diversity). Wasp guilds, i.e. gall inducers, kleptoparasites and parasitoids, presented similarly high turnover values. Our results showed that life-history traits play a role in the variation of β-diversity, as gall-inducing species are more host-specific. In contrast, kleptoparasitic and parasitoid wasps are more likely to use multiple hosts. Mantel tests revealed that both total β-diversity and the turnover component were often positively correlated with geographic distance, particularly for the most sampled fig species. Despite the exceptional dispersal capacities reported for several fig wasp lineages, our results suggest that competition for limited fig inflorescence resources, along with natural selection for local adaptation, can restrict species' geographic ranges, thus promoting higher levels of species turnover. These findings underscore the complex interplay between dispersal ability, local adaptation and competitive interactions in shaping the composition of fig wasp communities. Consequently, fig wasp systems present a compelling model for investigating the ecological and evolutionary processes driving biodiversity dynamics in specialized plant–insect interactions.