Dr. Naomi Levine is the Gabilan Distinguished Professor of Biological Sciences, Quantitative and Computational Biology and Earth Sciences, and Vice-Chair of Marine & Environmental Biology at the University of Southern California. Dr. Levine studies marine microbiology and will be telling us about her work modeling how marine phytoplankton adapt our changing global climate.

Dr. Naomi Levine
Department of Biological Sciences
University of Southern California

Hitting a Moving Target: Understanding Phytoplankton Adaptation in a Dynamic Ocean

Phytoplankton are vitally important for maintaining a habitable planet. Understanding how these essential microbes will evolve as the oceans change is essential for predicting future shifts in marine ecosystem dynamics, global carbon cycling and climate. However, we still lack fundamental knowledge about how phytoplankton may adapt to future environmental changes. Current global ocean models assume that size structured phytoplankton communities have fixed trait relationships, and as a result generally predict that smaller size classes will become more dominant globally. However, there is increasing evidence that intra-species trait tradeoffs may not follow large-scale inter-species tradeoffs—allowing for alternative evolutionary trajectories. We are tackling this problem by combining evolutionary theory, experiments, and biogeochemical models. We have demonstrated that environmental fluctuations, driven by ocean physics, drive a trade-off between two evolutionary strategies which determine whether and how fast microbes adapt to environmental change. We are also building cellular proteome allocation models to develop a mechanistic understanding of trait trade-offs and the implications of these trade-offs for ecosystem dynamics and carbon cycling. Our results suggest that modeling dynamic trait adaptation that is constrained by energetics and physical limitations is essential for predicting the functional diversity and size distributions of future marine microbial ecosystems.