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Abstract
Microbes represent the majority of biomass and diversity found on planet earth and are essential to the maintenance of global biochemical processes. However, there is still much that is unknown about what drives the formation and maintenance of complex microbial communities. Here, we explore the ecology of complex microbial communities through an examination of the cockroach gut microbiome. The cockroach gut microbiota is highly complex and is analogous to the human gut microbiome in structure, function, and overall diversity. Insects in the superorder Dictyoptera include: carnivorous praying mantids, omnivorous cockroaches, and herbivorous termites. We use 16S rRNA amplicon sequencing to survey the structure and diversity across of gut microbiota 237 cockroaches in the Blattodea order. Results show that host species plays a key role in the gut microbiota of cockroaches. This suggests that cockroach host-microbe coevolution preceded the emergence and possibly facilitated the dietary specialization of termites. Previous work suggests that diet is plays an important role in shaping the Blattodea gut microbiome. We conducted a series of dietary perturbations to determine the effect of diet on the structure of the cockroach gut microbiome. We found the cockroach hosts a taxonomically stable gut microbiome, which may aid the host in survival during low-food and/or starvation events. This stability is highly unusual and has not been found in any other animal that hosts a complex gut microbial community. This suggests that cockroaches have evolved unique mechanisms for establishing and maintaining a diverse and stable core microbiome. Cockroaches and termites are known for their diverse gut microbiota, however little is known about the praying mantid gut microbiome. In order to better understand the mantid gut microbiome, we conducted a 16S rRNA gene-based study of gut microbiome composition in adults and late-instar larvae of three praying mantis species. We found that few microbial lineages are shared among praying mantids and cockroach relatives. This adds further support for the role of microbes in facilitating dietary specialization among insects in the superorder Dictyoptera and is an important area for future study.