Assessing the diversity and stability of gut bacteria in Cephalotes varians

Ants are ecologically dominant insects that are known to occupy most of the Earth’s terrestrial biomes. They have a variety of diets ranging from relatively balanced to extremely unbalanced in nutrient content. It has been hypothesized that several groups of ants have evolved herbivorous diets with the aid of nutritional gut symbionts and that they have also evolved mechanisms to favor the acquisition, transmission, and maintenance of these potentially beneficial microbial gut flora. In this study, we aimed to explore the diversity and stability of gut associates in Cephalotes varians, an herbivorous ant from the Florida Keys. To accomplish this, we used a culture-independent approach to study bacterial gut communities through analyses of the 16S rRNA gene, including 454 pyrosequencing and T-RFLP analysis. T-RFLP analyses revealed high similarity between gut microbes in different ant workers, even those fed on different diets, and also showed that ants from the same colony tend to harbor more similar gut bacteria compared to ants from different colonies. In addition analyses of our 454 pyrosequencing data showed a trend of greater similarity of microbial gut communities within (versus between) ant colonies, although the predominant bacterial taxa from adult workers were found across all colonies. In contrast, gut bacterial communities showed drastic differences between adults and larvae from the same colonies. Combined, these results suggest C.varians may harbor relatively stable bacterial gut communities that could supplement nutritional deficiencies for their hosts. Yet they also suggest that the functional roles could very well differ between developmental stages.