The Larval and Adult Female Gut Microbiomes of Two Burying Beetles ( <i>Nicrophorus</i> spp.) With Distinct Parental Care Traits

Burying beetles (Nicrophorus spp.) exhibit parental care behaviours well-suited for studying gut microbiome and holobiont evolution. Theory predicts that differences in transmission can contribute to gut microbiome variations. We show that microbiome diversity estimates were comparable between reproductive females of common-garden-reared colonies of Nicrophorus marginatus (facultative parental care) and Nicrophorus orbicollis (obligate parental care). In contrast, the respective associated larvae of both species differed significantly. Furthermore, larval microbiomes clustered with respective adult female microbiomes but differed from each other. Fifteen bacterial families underscored differences in community composition between beetle species, with Wohlfahrtiimonadaceae significantly more abundant in N. orbicollis than N. marginatus. Results suggest that differences in parental transmission (trophallaxis) and larval acquisition of microbes possibly impact the parental-offspring gut microbiome dynamic. Close association of parental and larval microbiomes in the facultative parental care species is attributed to environmental acquisition from prepared carcasses and limited trophallaxis in larvae. However, the distinct larval and parental microbiomes in the obligate parental care species are attributed to the selective sorting of functionally relevant microbes from parents in larvae. Further examination of this genus's parental care behaviours and gut microbiome dynamics may offer insight into the possible evolutionary and ecological implications and general outcomes.