A fundamental question in biology is how cell populations evolve into different subtypes based on homogeneous processes at the single cell level. It is generally assumed that regulatory mechanisms must be in place to enforce some asymmetry at cell division and, therefore, at the single cell level. Here we show that population bimodality can emerge in a more natural way, due to the stochastic partitioning of a cell component with an optimal copy number. Within a mathematical model, we show the possibility of unimodal or bimodal distributions depending on the variance of partition errors and the growth rate tolerance around the optimal copy number. Our theory provides a simple explanation for the emergence of aneuploid states in a population  .
A fundamental question in biology is how cell populations evolve into different subtypes based on homogeneous processes at the single cell level. Here we show that population bimodality can emerge even when biological processes are homogenous at the cell level and the environment is kept constant. Our model is based on the stochastic partitioning of a cell component with an optimal copy number. We show that the existence of unimodal or bimodal distributions depends on the variance of partition errors and the growth rate tolerance around the optimal copy number. In particular, our theory provides a consistent explanation for the maintenance of aneuploid states in a population . The proposed model can also be relevant for other cell components such as mitochondria and plasmids, whose abundances affect the growth rate and are subject to stochastic partition at cell division .
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