  In nature microbial populations are subject to fluctuating nutrient levels.
Nutrient fluctuations are important for evolutionary and ecological dynamics in
microbial communities since they impact growth rates, population sizes and
biofilm formation. Here we use automated continuous-culture devices and
high-throughput imaging to show that when populations of Escherichia coli are
subjected to cycles of nutrient excess (feasts) and scarcity (famine) their
abundance dynamics during famines depend on the frequency and amplitude of
feasts. We show that frequency and amplitude dependent dynamics in planktonic
populations arise from nutrient and history dependent rates of aggregation and
dispersal. A phenomenological model recapitulates our experimental
observations. Our results show that the statistical properties of environmental
fluctuations have substantial impacts on spatial structure in bacterial
populations driving large changes in abundance dynamics.
