Gomard Y. auteur aut IRD Flores O. auteur aut IRD Vittecoq M. auteur aut IRD Blanchon T. auteur aut IRD Toty Céline auteur aut IRD Duron O. auteur aut IRD Mavingui P. auteur aut IRD Tortosa P. auteur aut IRD McCoy K. D. auteur aut IRD text journalArticle eng text/pdf born digital access Characterising within-host microbial interactions is essential to understand the drivers that shape these interactions and their consequences for host ecology and evolution. Here, we examined the bacterial microbiota hosted by the seabird soft tickOrnithodoros maritimus(Argasidae) in order to uncover bacterial interactions within ticks and how these interactions change over tick development. Bacterial communities were characterised through next-generation sequencing of the V3-V4 hypervariable region of the bacterial 16S ribosomal RNA gene. Bacterial co-occurrence and co-exclusion were determined by analysing networks generated from the metagenomic data obtained at each life stage. Overall, the microbiota ofO. maritimuswas dominated by four bacterial genera, namelyCoxiella,Rickettsia,BrevibacteriumandArsenophonus, representing almost 60% of the reads. Bacterial diversity increased over tick development, and adult male ticks showed higher diversity than did adult female ticks. Bacterial networks showed that co-occurrence was more frequent than co-exclusion and highlighted substantial shifts across tick life stages; interaction networks changed from one stage to the next with a steady increase in the number of interactions through development. Although many bacterial interactions appeared unstable across life stages, some were maintained throughout development and were found in both sexes, such asCoxiellaandArsenophonus.Our data support the existence of a few stable interactions inO. maritimusticks, on top of which bacterial taxa accumulate from hosts and/or the environment during development. We propose that stable associations delineate core microbial interactions, which are likely to be responsible for key biological functions. specialized Ornithodoros maritimus Bacterial interactions Network analyses 16S rRNA gene 080 034 052 084 81 3 770-783 2021 0095-3628 https://www.documentation.ird.fr/hor/fdi:010079826 10.1007/s00248-020-01611-9 0095-3628 [F B010079826] https://www.documentation.ird.fr/hor/fdi:010079826 https://www.documentation.ird.fr/intranet/publi/2020/10/010079826.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2020-11-12 2025-02-24 fdi:010079826 fre