NBIA Colloquium: Ray Goldstein

TITLE/ABSTRACT - Algal Phototaxis and the Evolution of Multicellularity

 A fundamental issue in biology is the nature of evolutionary transitions from unicellular to multicellular organisms. Green algae are models for this transition, as they span from the unicellular species to multicellular ones with tens of thousand of cells, all of which swim through the action of flagella that are closely related to the cilia found throughout the human body. The mechanism by which these organisms steer toward light (phototaxis) is of particular interest since they lack a nervous system and intercellular connections; steering is a consequence of the response of individual cells to light.

In this talk I will describe experimental and theoretical work on the physical mechanism of phototaxis in species of green algae, spanning 3 orders of magnitude in cell number. We find an evolutionarily conserved dynamics, with a tuning between the time scales for an adaptive flagellar response to changing light levels and the spinning frequencies of the microorganisms. The implication of these results for the evolution of multicellularity are discussed.

 Raymond Goldstein received undergraduate degrees in physics and chemistry from MIT, and a Ph.D. in theoretical condensed matter physics from Cornell University. Following postdoctoral work at the University of Chicago and faculty positions in physics and applied mathematics at Princeton University and the University of Arizona, he moved to the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge in 2006 as the Schlumberger Professor of Complex Physical Systems. His research interests span from statistical physics to nonlinear dynamics and geophysics, with particular emphasis on biological physics, both theoretical and experimental. His work has been recognized by a Sloan Foundation Fellowship, a Presidential Faculty Fellowship from the National Science Foundation, the G.K. Batchelor Prize in Fluid Mechanics, the Rosalind Franklin Medal of the Institute of Physics (UK) and Fellowship in the American Physical Society, the Institute of Physics, the Institute of Mathematics and its Applications and the Royal Society. He shared the 2012 Ig Nobel Prize in Physics for work on the shape of a ponytail.