Spatial Information, Information Flows, and Dissipation in Models for Migration Waves of Chemotactic Bacterial Populations.

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Many biological species form groups in order to increase chances of survival. These groups often rely on communication between individuals to retain their structure. In these cases, each individual needs to invest into the group by providing information but gains benefits from the information it can extract. This project will quantify the fundamental rules governing this type of information exchange by using migration waves of chemotactic bacterial populations as a model. These are bacteria that chase a chemical gradient which is generated by their collective consumption.The interactions in this system are mediated by the spatial structure in the chemical composition of the environment. Individual bacteria generate information locally by consuming or secreting chemicals, and they extract information by detecting time-dependent changes and gradients in the chemical fields generated by the group. The environment thus mediates an indirect communication exchange.I will model this process in three stages: First, I will apply recent ideas from nonequilibrium thermodynamics to account for the information contained in the spatial structures that an individual imprints on its environment, and the work that is required to do so. Second, I will extend a measure of information flow from information theory to the cellular scale in order to quantify how much information a sensing cell can receive about spatial structures in its environment. Last, I will combine these insights to model the information exchange processes in a population of chemotactic bacteria that forms a migration wave.With this theoretical model I will be able to quantify how information is flowing through this system, how much energy is required to maintain the wave structure, how much energy is being dissipated, and how efficient this process is. I will furthermore be able to evaluate to which extent diversity in a bacterial population is beneficial or detrimental to maintaining the group's structure.