DISSERTATION RESEARCH: Functional ecology and evolution of an ant gut microbiome

Harvard University, Cambridge MA

Investigators

Abstract

In nature, the hidden things often make the most difference. For example, in the rainforests of South America, fungus-gardening ants consume more leafy vegetation than any other herbivore. In the forest canopy, other ants may compose more than 50% of all insect biomass. But how do these tiny herbivores affect the forest ecosystem? The answer may lie with an even more hidden player: bacteria. Like coral reefs, cows, and even humans, many insects rely on symbiotic microbes to augment their diets. There are hints that bacteria may play an especially important role for ?herbivorous? ants, or those ants whose diet consists primarily of nectar, extra-floral nectar, and other plant-derived resources. However, little is known about the evolution, ecology, and function of the microbial partners of herbivorous ants. This study aims to uncover some of the mysteries surrounding ant/bacteria symbioses using the canopy-dwelling tropical ant genus Cephalotes as a model system. Cephalotes are among the most herbivorous of known ants, and have long been known to host an unusually dense population of bacteria, or microbiome, in their guts. Using next-generation DNA sequencing technology, this study will address the following questions: Have Cephalotes gut bacteria co-evolved with their hosts? How does the Cephalotes gut microbiome change among host species, nests, locations, and across host development? What can the genomes of Cephalotes gut bacteria indicate about their function? Broader Impacts: The answers to these questions will clarify the role played by bacterial symbionts in one of the most important and least understood elements of tropical rainforest ecology. Additionally, data and techniques from this study will help to disentangle the evolutionary and ecological dynamics operating within symbiotic gut communities themselves. These communities have both direct (via diseases like Inflammatory Bowel Disease) and indirect (via association with agricultural pests such as locusts and aphids) impacts on human society, and yet they remain poorly understood. This research will provide training opportunities for students in cutting-edge areas of sequencing and data analysis, and the results will be communicated to the public via ongoing museum- and K12-based outreach activities.