Emerging Ecological Roles of Viruses in the Polar and Global Oceans
***Tuesday May 29, 2012
Redfield Auditorium - 12:00 Noon
Dr. Jennifer Brum
The University of Arizona
Marine microorganisms drive the biogeochemistry that fuels the Earth system, and viruses exert considerable control over these microorganisms through mortality, horizontal gene transfer, and the expression of viral-encoded ‘host’ genes during infection. Here, I will first characterize and explore the ecological roles that viruses play in globally-important polar marine environments. Ecological characterization in the highly productive ocean near the Western Antarctic Peninsula documented extreme seasonal variation in bacterial production complemented by an apparent shift in viral lifestyles (lytic vs. lysogenic) that was either due to different viral communities or life history switches of the same viruses. Large-scale comparative metagenomics differentiated between these hypotheses and clearly showed that this polar viral assemblage was dominated by viruses that switched lifestyles in response to changes in bacterial productivity. This also differentiated them, ecologically and genetically, from viruses in lower latitude oceans and provided hints of important ‘cold-adaptive’ functions critical to viral success in polar environments. Next, I will broaden my scope to present a study designed to evaluate the morphological and sequence-based characteristics of ocean viral communities around the globe. Despite sampling across vast spatial scales (Mediterranean, Red, and Arabian Seas and the Pacific, Atlantic, and Indian Oceans), viral communities appeared relatively similar at the level of morphology. Direct comparison of morphological data with select metagenomes revealed extensive viral genomic diversity that has yet to be discovered, and hints at particular viral groups of interest for targeted study. Together these stories demonstrate how, particularly in viral ecology, coupling traditional and new methods can provide synergy that furthers our understanding of these vastly under-explored, most abundant biological entities on the planet.