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theses

Through time, ants have developed different adaptations as a means of survival, one being caste specialization. Lineages with a specialized honeypot ant replete caste have acquired an innovative means of food storage. Honeypot ant repletes store liquid food in their crop which is redistributed through trophallaxis when food sources are scarce. Repletism is found across distantly related ant genera, but the temporal history and phylogenetic distribution of this phenotypic phenomena remains unknown. I reconstructed the evolutionary history of this adaptive behavior and examine the role of microbes in repletism. I expected that this dietary adaptation would be consistent with a conserved microbiota. I described the first known instance of repletism in the fossil record in the genus Leptomyrmex from Dominican amber dating to approximately 16 mya. I mapped the history of this trait onto a time-calibrated phylogeny of extant ants; results suggest that certain lineages are more prone to repletism, and that the origin likely occurred in the Eocene and Miocene. To determine if honeypot ants have a resident gut microbiome, I isolated bacteria from the crop and midgut of Myrmecocystus honeypot ants. I isolated a total of 150 microbes, belonging to five phyla: Bacillota, Actinomycetota, Proteobacteria, Ascomycota and Basidiomycota. Using 16S rRNA sequences, I reconstructed phylogenies of the isolated microbes and closely related strains from the same genera. I used presence/absence data of these different genera to look for patterns of association with their ant hosts. Additionally, I performed tannin degradation assays using isolates to test the degradation of known acids from the toxic creosote bush, a common food source for Myrmecocystus honeypot ants. My preliminary data suggest that honeypot ants have a resident gut microbiome and some of these microbes may play a role in detoxifying tannins. The gut microbiome may play an important role in the ability of repletes to retain liquid for long periods of time, remediate toxins, or supplement nutrients. My study of the evolutionary history of this behavior in combination with analysis of the gut microbiome provides the starting point to further studies of the evolution and natural history of this convergently-evolved trait.

http://dissertations.umi.com/gsn.newark.rutgers:10287

M.S.

Includes bibliographical references

doi:10.7282/t3-vwe9-6f82

The author owns the copyright to this work.