Speaker: Prof. Uri Alon, Weizmann Institute of Science

Title: 'Evolutionary tradeoffs and the geometry of gene expression space'

Abstract: Organisms, tissues and molecules often need to perform multiple tasks. But usually no phenotype can be optimal at all tasks at once. This leads to a fundamental tradeoff. We study this using the concept of Pareto optimality from engineering and economics. Tradeoffs lead to an unexpected simplicity in the range of optimal phenotypes- they fall on low dimensional shapes in trait space such as lines, triangles and tetrahedrons. At the vertices of these polygons are phenotypes that specialize at a single task. One does not need to know the tasks in advance; tasks  can be inferred from the data. We demonstrate this using animal and fossil morphology, bacterial and stem-cell gene expression and other biological systems.