Basset, Y. | Search bioRxiv

bioRxiv2026

Spatial turnover amplifies with trophic level in hyperdiverse food webs

One of the most intuitive ideas in ecology is that diversity at lower trophic levels in food webs provides niches to support diversity at higher trophic levels. This accumulation of diversity can be limited by survival of species in the landscape, but revealing these limits has been challenging. We analyze spatial turnover in a hyperdiverse parasitoid-caterpillar-plant food web across 75,000 km2 of continuous lowland rainforest in Papua New Guinea. Species turnover across sites is higher in parasitoids than in their caterpillar hosts. Furthermore, turnover of interactions is also higher in parasitoid-caterpillar than caterpillar-plant networks. Spatial turnover thus amplifies upwards across trophic levels, forcing parasitoids to live closer to spatial persistence limits. Consequently, progressing rainforest fragmentation can especially endanger parasitoids.

ecology↗

bioRxiv2025

The magnitude of cryptic insect diversity in one tropical rainforest

O_LICryptic species represent significant entities in conservation planning and are common among tropical insects. Many studies focusing on cryptic species have been restricted to a narrow taxon and it is not clear whether some insect clades or assemblages may have a greater propensity for cryptic speciation than others. Here, we contrast cryptic diversity among 22 insect assemblages surveyed on Barro Colorado Island (BCI), a tropical rainforest in Panama. C_LIO_LICryptic species were defined as externally indistinguishable from their sister species but with a different barcode index number. We detected 214 cryptic species out of a total of 2,006 species studied (10.6%). The percentage of cryptic species varied greatly among assemblages (0-19%), with half of assemblages devoid of cryptic species, and the highest proportions of cryptics in Pieridae and Formicidae. C_LIO_LIThe percentage of cryptic species was weakly influenced by phylogeny and it was best explained by the local number of species and an index of taxonomic knowledge. Cryptic species were distinguished by an average distance divergence in sequence of 9%, but their ecological characteristics remain unclear. C_LIO_LIAsymptotic estimates indicated that 11.4% of species studied on BCI may be cryptic. Since many of the species-rich insect assemblages occurring on BCI were not considered in this study, this estimate probably represents a lower bound to the true cryptic insect richness on BCI. C_LIO_LIThis significant contribution to biodiversity should not be ignored and, because of apparent low population levels, may be particularly vulnerable to land use and climate changes. C_LI

evolutionary biology↗