Tuesday
December 3
11:10 a.m.
Room 230

Marcus
Feldman (Stanford  Department of Biological Sciences)
Mathematics and Computation in Phenotypic Switching (slides)
Phenotypic switching is the property of cultures of some bacteria
and other microbes, including yeast, to change aspects of their phenotypes
in response to environmental perturbation. This has been framed as
a kind of "bethedging." Mathematical models of phenotypic
switching assume that the two phenotypes can be represented as genes
whose fitnesses change cyclically or randomly. The rate of mutation
between these genes evolves in response to the changes in fitnesses.
We derive mathematical representations for the evolution of the mutation
rate in cyclic environments and show how the stable mutation rate
depends on symmetry assumptions on the fluctuating fitnesses. Computer
analyses show fascinating complexities with asymmetric selection.
