Award Announcement - EAGER: Exploring Phylogenetic Diversification of Phycodnaviruses Across Aquatic Ecosystems in the Puget Sound Region

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Viruses are the most abundant, widespread, and diverse biological entities on earth. To date most viruses have been intensely studied in light of animal and plant health. Yet, these viruses are a small fraction of the earth's total viral biodiversity, and as a result the vast majority of viruses on earth remain unexplored. Studying virus diversity is a major challenge in biology with important consequences for understanding the earth's biosphere. To address this challenge, this project will study phycodnaviruses, an exceptionally diverse group of viruses that infect algae found in lakes, rivers, and oceans around the world. Phycodnavirus diversity and population dynamics will be explored in lakes which are critical natural resources impacted by local and regional environmental changes. The results of the study will be of broad importance as these viruses affect algal blooms and ultimately the cycling of nutrients within lakes. The study of phycodnaviruses will be of use to other scientists and provide valuable information for the management of freshwater resources. The research will fill fundamental gaps in our knowledge by discovering novel viruses and determining the environmental conditions driving virus diversity in lakes. This research will also provide a powerful platform for training undergraduate students in a broad range of scientific methods and enhance both student and public appreciation for the hidden biodiversity within lakes.

Phycodnaviruses provide a model system for exploring phylogenetic patterns of diversification based on their extreme diversity (~350,000 'species'), high abundances, ecological roles, rapid turnover rates, and biogeographic distributions. Using well-developed metagenomic and phylogenetic methods, an innovative longitudinal survey in the Puget Sound region will be used to discover the ecological and phylogenetic diversification of phycodnaviruses across freshwater ecosystems that vary in nutrient levels and host composition. In addition to the discovery of phycodnavirus lineages, this research tests the hypothesis that patterns of phycodnavirus diversity and abundance (onset, peak, and decline) are influenced by changes in aquatic environmental conditions among lakes. The project will characterize phycodnavirus diversity through two approaches: targeted sequencing of the polymerase B gene and phycodnaviral whole-genome sequencing from environmental DNA samples across urban and wilderness lakes. Phylogenetic, bioinformatic, and statistical analyses of DNA sequences and limnological measures will be used to identify patterns and relationships between viral diversity, seasonality, and environmental variables. This research is expected to discover novel phycodnavirus lineages with unique genome architectures, high levels of viral diversity within and between lakes, and clear examples where novel viral lineages emerge to generate new species assemblages linked with season and/or geography.