CAREER: Mechanisms of Specificity and Homeostasis in an Obligate Symbiosis: Discovery-based Research at a Regional University

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This project will examine the roles that bacteria play in stabilizing the interactions among the so-called fungus-gardening ants and their farmed fungi. These ants are ecologically important members of desert and forest ecosystems throughout the southern US and tropical regions of North and South America. Understanding these organisms informs us how they influence and interact with their environment. Detailed studies and experiments in this project have important societal and scientific benefits. For example, some ant-fungal symbioses are important agricultural pests. Others are sources of antibiotics and antimicrobial compounds, while others serve as models for biofuel production. This research will train undergraduate and graduate students in experimental biology, microbiology and the analysis of large molecular datasets as well as increase the national and international exposure of students at a regional university in east Texas. Outreach activities include but are not limited to (a) construction of a living leaf-cutter ant exhibit at a local museum, (b) construction of interpretative exhibits in the UT Tyler Nature Preserve (c) the development of new courses at UT Tyler that emphasize connections between the environment, biomedicine and human health (d) participating and co-organizing the annual UT Tyler Darwin Day. Symbioses (ecological associations of unrelated organisms living in close proximity) were and are crucial to the evolution and ecological success of all life on earth. One of the central issues facing the study of symbiosis is elucidating how symbioses are organized and function in a dynamic world. Fungus-gardening (attine) ants form an obligate macrosymbiosis with specific fungi that the ants grow for food, but also interact with a number of other bacteria and microfungal species. The attine symbiosis is an excellent model to address functional relationships because the ants and fungi can be experimentally disassembled and reassembled into novel combinations, thus making it possible to demonstrate links among colony and fungal performance and microbial community composition. Of particular interest in this project is the roles that the microbial communities (microbiomes) associated with attine ants and the fungi play in the maintenance of the ant-fungus community. The proposed experiments will examine how interactions with the microbiomes promote specificity and homeostasis with the various partners in this symbiosis. This discovery-based research will combine intensive field surveys, next generation sequencing, bioinformatics and experimental biology to examine the role of the bacterial communities in conferring stability between host ants and symbiotic fungi. As a result, this research has broad implications for understanding the evolution and maintenance of obligate symbioses.