Geographic Variation in the Bacterial Microbiota of Rhipicephalus sanguineus (Acari, Ixodidae) Across Environmentally Contrasting Regions of Mexico

Geographic and ecological variations are frequently associated with differences in the microbiota of arthropod vectors, with potential implications for pathogen transmission and public health. This study characterized and compared the bacterial microbiota associated with the brown dog tick (Rhipicephalus sanguineus) across three ecologically contrasting regions of Mexico: Cancun (Quintana Roo), Comarca Lagunera (Durango–Coahuila), and Hermosillo (Sonora). Non-engorged ticks collected from stray dogs were analyzed using 16S rRNA gene (V3–V4) sequencing. Amplicon sequence variants (ASVs) generated in QIIME2 were used for taxonomic, diversity, and predictive functional analyses. Proteobacteria dominated all samples, with Coxiella-like bacteria tentatively assigned as Coxiella mudrowiae identified as a dominant taxon across all localities. Significant geographic differences were observed in alpha and beta diversity, with Comarca Lagunera showing the highest diversity and Hermosillo the lowest. Sequences tentatively assigned to Rickettsia rickettsii were detected exclusively in two pools from Hermosillo. Functional predictions revealed a conserved metabolic repertoire alongside geographic variation in pathway abundance. Overall, the results support the existence of a stable symbiotic component accompanied by a geographically variable bacterial fraction associated with ecologically contrasting regions. These findings highlight the importance of geographic context in shaping tick-associated bacterial communities.