Speaker
Description
Single-cell experiments revealed substantial variability in generation times, growth rates, birth and division sizes between genetically identical cells. Understanding how these fluctuations determine the fitness of the population, i.e. its long-term growth rate, is necessary in any quantitative theory of evolution. In this talk, I will present a biologically relevant agent-based model of population dynamics which accounts for single-cell stochasticity. I will derive expressions for the population growth rate and mean birth size in the population in terms of single-cell fluctuations. Allowing division sizes to fluctuate reveals how the mechanism of cell size control (timer, sizer, adder, ...) influences population growth. Surprisingly, we find that fluctuations in single-cell growth rates can be beneficial for population growth when slow-growing cells tend to divide at smaller sizes than fast-growing cells. Our framework is not limited to exponentially growing cells like Escherichia coli, and we derive similar expressions for cells with linear and bilinear growth laws, such as Mycobacterium tuberculosis and fission yeast Schizosaccharomyces pombe, respectively.
