Physics (Internal)

Student Seminar Series

This event is part of the Graduate Student Council Events.

Ashish George (BU, Bio Theory)
Eco-evolutionary dynamics of complex microbial populations with heterogeneous growth and dispersal

For continued survival in a spatial habitat, all organisms must migrate to new territories and reproduce. The interplay of these two fundamental processes—migration and reproduction—determines the outcome of species invasions, growth of cancer tumors, and stability of complex microbial communities. Understanding and controlling these systems requires ecosystem models that appropriately account for population heterogeneity. In this talk, I will describe three such modeling efforts in increasing order of population heterogeneity. First, I will describe a minimal model incorporating chiral bias in migration that quantitatively reproduces experimental patterns in bacterial colonies. Using this model, I demonstrate chirality can provide an evolutionary fitness advantage, and differences in cellular chirality can impact cancer invasion and species coexistence. I will present a general effective theory of chiral growth to explain the selection mechanism favoring chiral cells. Second, I describe a model of a growing bacterial colony composed of two sub-populations with distinct growth and migration strategies. I show how coordination in a cooperative population reproduces concentric rings and periodic boundary motion observed in P. mirabilis colonies, and discuss the implied evolutionary tradeoffs between exploration and exploitation. Finally, for populations of many heterogeneous interacting species, I study the process of assembling an optimal microbial community performing a desired function such as biofuel production, waste degradation, or disease treatment. I show that the difficulty of searching for the optimal community is determined by the structure of the “landscape” of community function.