Biology subjects

Theodorou, P.

Publications and source records attributed to Theodorou, P..

3 recordsLinked to original sources

bioRxiv2026

Seasonal variation mediates the importance of species attributes in plant-pollinator interactions

Predicting species interactions remains a major challenge, as multiple species attributes operate simultaneously and their relative importance may vary seasonally and with temporal resolution. Here, we assess how the relative contributions of abundance, trait matching, and phenology to plant-pollinator interactions vary through a flowering season and across temporal resolutions using interaction data from three European botanical gardens. We show that predictive models explain a substantial proportion of variation in visitation patterns, with floral and pollinator abundances consistently explaining most variation across the flowering season. Trait matching between pollinator body size and floral size also contributes to visitation patterns, playing a secondary but persistent role in shaping interactions, while phenology plays a relatively minor role at broader temporal resolutions but becomes more important at finer temporal scales. Additionally, null models accounting for spatio-temporal variation in floral and pollinator abundance reveal consistent patterns of pollinator preference and avoidance, indicating that abundance alone cannot explain the observed interaction patterns. Our results show that seasonal variation and temporal resolution differentially shape the importance of species attributes, highlighting the need for multi-variable approaches that account for temporal dynamics to accurately explain and predict ecological interactions.

ecology↗

bioRxiv2026

Rapid spread of nutritional Wolbachia symbionts across and within solitary bee species

Maternally inherited, intracellular Bacteria of the genus Wolbachia are extremely widespread among arthropods. Their evolutionary success is owed to frequent host shifts and rapid subsequent spread within host populations, often facilitated by Wolbachia-induced reproductive manipulations. Theory suggests that carrying Wolbachia must also be beneficial for a successful spread, however the nature of such benefits remains unclear. Here, we demonstrate that Wolbachias success in many solitary bee species is strongly associated with the presence of a gene cassette enabling Wolbachia to synthesize Biotin (vitamin B7). This ability is absent from almost all other Wolbachia strains but common among bee associated strains. We show that Wolbachia occurs in up to 70% of all bee species and that strains carrying this rare genomic element have independently spread into numerous bee hosts recently. We further demonstrate that the presence of the biotin operon is associated with specialised diets in several bee species, suggesting a previously overlooked nutritional role of Wolbachia in this group of important pollinators. Overall, our results suggest that nutritional benefits provided by symbionts may represent a more widespread and important mechanism by which reproductive manipulators spread into new host species than previously appreciated.

evolutionary biology↗

bioRxiv2025

Urbanisation drives biodiversity loss, fitness decline and community shifts in cavity-nesting Hymenoptera

Urbanisation is reshaping landscapes worldwide, posing challenges to biodiversity and ecosystem function. Cavity-nesting Hymenoptera, including bees and wasps, deliver vital ecological services but are increasingly vulnerable to urbanisation. In this citizen science-based study, we deployed 286 trap nests across Leipzig and Hamburg (Germany) to investigate how urbanisation and landscape-scale environmental features influence the diversity, community composition, reproductive success, offspring survival and demographic status of these insects. Using Bayesian hierarchical and phylogenetically informed modelling, we found that urbanisation significantly reduced species richness, reproductive output and offspring survival in both guilds, despite stable nesting activity, suggesting potential ecological trap effects. For bees, urbanisation also reduced the probability of nests functioning as demographic sources. Environmental drivers shaped responses in taxon-specific ways: bee richness and survival increased with landscape diversity but declined with fragmentation, while wasp richness and nesting declined with higher temperatures, though survival increased with more green cover. Bee nests were more likely to serve as demographic sources in higher temperatures. Community composition responses also diverged; bee communities shifted via increased species turnover, while wasp assemblages remained relatively stable. Temperature was a major driver of compositional dissimilarity in both groups, whereas landscape diversity was associated with homogenisation in bees and diversification in wasps. Our findings demonstrate that cities filter cavity-nesting Hymenoptera through multiple ecological pathways, highlighting the need for differentiated conservation strategies that consider both habitat structure and taxon-specific responses.

ecology↗