Starvation–refeeding dynamics shape microbiome assembly and functional adaptation in Ornithodoros turicata ticks

Extreme nutritional cycles govern microbial communities in many ecosystems. The soft tick Ornithodoros turicata , which can endure years of starvation punctuated by massive blood feedings, provides a unique natural model for investigating how this dynamic of nutritional abundance or scarcity shapes a vector’s microbiome. It was hypothesized that prolonged starvation acts as a selective filter, molding a resilient and functionally adapted community, and that subsequent refeeding triggers resource-specific restructuring. Using a two-phase experimental framework (long-term starved ticks and artificially refed subsets), diversity, assembly, and functional potential via 16 S rRNA sequencing, co-occurrence network analysis, and PICRUSt2 were characterized. Starvation favored a taxonomically richer community, with greater phylogenetic richness and diversity compared to refed ticks. Co-occurrence networks under starvation were cohesive and dominated by positive correlations, whereas refeeding resulted in networks with a higher proportion of negative correlations, indicating increased competition. Predicted functional profiles in starved ticks showed enrichment of pathways involved in alternative nutrient uptake (e.g., creatinine degradation), oxidative stress response, and energy conservation, hallmarks of a metabolically efficient, stress-adapted state. Refeeding triggered a profound restructuring: networks became more fragmented (higher modularity), and the predicted metabolome shifted toward pathways for blood meal degradation and biosynthesis of complex cofactors and lipids, reflecting a rapid, growth-oriented strategy. Notably, network comparisons revealed that pre-starvation blood meal history exerted a lasting influence on network topology, demonstrating path-dependent assembly (higher Graphlet Correlation Distances between starved and refed pairs). Despite drastic structural reorganization, core functional resilience was maintained across both states. This work decouples structural and functional responses of a vector microbiome to nutritional extremes, revealing that functional resilience persists despite taxonomic and network restructuring. These findings extend observations from hard ticks by showing that the transition from prolonged starvation to a post-feeding state is also associated with microbiome restructuring in a soft-tick system.