Abstract
Maternally inherited endosymbionts of arthropods are one of the most abundant and diverse group of bacteria. These bacterial endosymbionts also show extensive horizontal transfer to taxonomically unrelated hosts and widespread recombination in their genomes. Such horizontal transfers can be enhanced when different arthropod hosts come in contact like in an ecological community. Higher rates of horizontal transfer can also increase the probability of recombination between endosymbionts, as they now share the same host cytoplasm. However, reports of community‐wide endosymbiont data are rare as most studies choose few host taxa and specific ecological interactions among the hosts. To better understand endosymbiont spread within host populations, we investigated the incidence, diversity, extent of horizontal transfer, and recombination of three endosymbionts (Wolbachia, Cardinium, and Arsenophonus) in a specific soil arthropod community. Wolbachia strains were characterized with MLST genes whereas 16S rRNA gene was used for Cardinium and Arsenophonus. Among 3,509 individual host arthropods, belonging to 390 morphospecies, 12.05% were infected with Wolbachia, 2.82% with Cardinium and 2.05% with Arsenophonus. Phylogenetic incongruence between host and endosymbiont indicated extensive horizontal transfer of endosymbionts within this community. Three cases of recombination between Wolbachia supergroups and eight incidences of within‐supergroup recombination were also found. Statistical tests of similarity indicated supergroup A Wolbachia and Cardinium show a pattern consistent with extensive horizontal transfer within the community but not for supergroup B Wolbachia and Arsenophonus. We highlight the importance of extensive community‐wide studies for a better understanding of the spread of endosymbionts across global arthropod communities.
Highlights
Inherited endosymbionts, infecting arthropods, are one of the most diverse and abundant of all bacteria infecting them
Our study indicates that supergroup A Wolbachia and Cardinium are showing greater sequence similarity within the community indicating, perhaps, that such horizontal transfer events are more prevalent in these two endosymbionts than in supergroup B Wolbachia and Arsenophonus
If an ecological community is the primary site of horizontal transfer of endosymbionts, the same bacterial strains would be found in multiple host taxa
Summary
Inherited endosymbionts, infecting arthropods, are one of the most diverse and abundant of all bacteria infecting them. A well-defined ecological community will have several diverse host taxa with significant overlap of niches as they are interacting with each other This physical contact of the hosts can facilitate the horizontal transfer of their resident endosymbionts (Sanaei et al, 2021). If endosymbionts are rapidly undergoing horizontal transfer within a particular ecological community, very similar bacterial strains would be found among the arthropod hosts of that community This would make these bacteria more closely related to each other, resulting in lower than expected pairwise sequence divergence among them. Our study indicates that supergroup A Wolbachia and Cardinium are showing greater sequence similarity within the community indicating, perhaps, that such horizontal transfer events are more prevalent in these two endosymbionts than in supergroup B Wolbachia and Arsenophonus
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