D3370: Investigating the microbiome of honeypot ants, Myrmecocystus mexicanus

In animals, extreme feeding strategies often depend on the assistance of microbes located in the host’s digestive system. Ants are a highly diverse and well-studied group with more than 14,000 described species, some of which have evolved extreme feeding strategies that allow them to exploit novel niches. In this study, we focus on a group of ants known as “honeypot ants,” which is composed of at least sixteen independently-evolved genera located in the arid regions of North America, Africa, and Australia. All lineages have a specialized worker caste known as repletes, which store foraged sugar- or protein-rich fluids in their gasters for long periods of time and supply the colony with these nutrients during times of scarcity. Repletes specifically store resources in an expandable digestive organ, the crop. Here, we focus on the North American honeypot ant genus, Myrmecocystus spp., to taxonomically and functionally characterize the microbial communities between different digestive organs, castes, and colonies. Using culture-based methods and 16S rRNA amplicon sequencing of Myrmecocycstus mexicanus ants from Arizona, we have found significantly different microbial communities between M. mexicanus digestive organs, while the worker and replete castes within each colony share similar taxa. In particular, the crops of both repletes and workers are dominated by strains in the genus Fructilactobacillus. This work lays the foundation for future comparisons of microbial composition and function between different lineages of honeypot ants to better understand the relationships between gut microbiomes, niche specialization, and convergent evolution.