In partial fulfillment of the requirements for the degree of 

Doctor of Philosophy in Quantitative Biosciences

in the School of Biological Sciences

Daniel Muratore

Defends their thesis:

Emergence of Marine Biogeochemical Dynamics Across Scales Drive by Complex Microbial and Viral Communities

Thursday, June 9th, 2022
11am Eastern Time
Klaus Advanced Computing Building
1116 East Seminar Room

Virtual =  https://gatech.zoom.us/j/93131163215

Open to the Community

Advisor:

Dr. Joshua Weitz

School of Biological Sciences, School of Physics

Georgia Institute of Technology

Committee Members:
Dr. Takamitsu Ito

School of Earth and Atmospheric Sciences

Georgia Institute of Technology

Dr. B. Aditya Prakash

School of Computational Science and Engineering

Georgia Institute of Technology

Dr. Frank Stewart

Department of Microbiology and Immunology

Montana State University

Dr. Angelicque White

Department of Oceanography, Center for Microbial Oceanography: Research and Education

University of Hawai’i at Mānoa

Abstract:

Marine microbial populations are subject to the dual pressures of bottom-up nutrient limitation and top-down infection by abundant viruses. However, top-down and bottom-up controls do not act independently. Environmental conditions also have a large impact on the ecology and evolution of viral populations. This thesis explores the mutual feedbacks between the bottom-up and top-down drivers of marine microbial ecosystems.

The first part of this thesis studies two Lagrangian field campaigns conducted in oligotrophic gyres – one in the North Pacific and one in the Sargasso Sea. Emergent ecosystem-level diel cycles in nutrient uptake and assimilation show partitioning of key limiting resources. We also identify diel coordination of viral gene transcription across vast viral diversity.

The second part studies eco-evolutionary responses of marine virus infection strategies and variable environmental conditions. A comparative metagenomic study of genomic and proteomic nitrogen content across the Eastern Tropical North Pacific oxygen minimum zone identifies genome streamlining in bacteria, archaea, and viruses across nitrogen gradients. Then, we construct and analyze a game theoretic model of the evolution of strategies for viruses and their hosts in iron-limited environments, where viruses can use specialized host iron uptake mechanisms to facilitate infection. We identify conditions for the coexistence of hosts with and without this iron uptake capacity, and viruses that do or do not leverage it for infection.