Katie MacGillivray is a third year PhD student in the Quantitative Biosciences program. She is co-advised by Will Ratcliff and Brian Hammer, with a project in each lab using experimental evolution to study the ways that cooperation and conflict shape the evolution of microbes. In the Ratcliff lab, she uses flocculating baker’s yeast to investigate the ways that aggregative multicellular organisms can adapt as groups. One key concept is that positive assortment – evolved genotypes being enriched within their groups – is required in order for selection acting on groups to drive group-level adaptation. In the Hammer lab, she has evolved E. coli to become ~100-fold more resistant to attack by the Type VI secretion system. The genetic changes that have led to this increased resistance are all accompanied by a decreased growth rate. Katie is interested in exploring this fitness tradeoff, because it is essential for the widespread success of the Type VI Secretion system – if other organisms could easily evolve resistance, it would not be effective. Katie is also a trainee in the InQuBATE T32 program, led by Joshua Weitz and Peng Qiu, where she is learning machine learning data science approaches to apply to her research. Outside the lab, she loves to knit, garden, and grow mushrooms.