A Continuous-Time Stochastic Model for Mutation Effects in Microbial Population

MojganEzadian

Lindi Wahl, Western University

"A Continuous-Time Stochastic Model for Mutation Effects in Microbial Population"

Mutation accumulation (MA) experiments are crucial for understanding evolution. In microbial populations, these experiments typically involve periods of population growth, where a single individual forms a visible colony, followed by severe bottlenecks. Studies on the effects of positive and negative selection in MA experiments have shown that, for example, with 20 generations of growth between bottlenecks, beneficial mutations will be substantially over-represented cite{}; this effect is known as ``selection bias''. In previous work, we developed a fully stochastic discrete-time model that includes realistic offspring distributions, accounting for genetic drift and allowing for the loss of rare lineages. We demonstrated that when drift is included, selection bias is even stronger than previously predicted cite{}. Since bacterial division is unlikely to remain synchronized over 20 or more generations, this study extends the discrete-time model to a continuous-time framework. Since lineages that start reproducing early accrue a compounded advantage, a continuous-time model offers an even more accurate correction for selection in MA experiments.
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