Abstract
Aleeza C. Gerstein works in the field of microbial evolutionary genetics in human fungal pathogens. In this mSphere of Influence article, she reflects on how the papers "Experimental tests of the roles of adaptation, chance, and history in evolution" by Travisano et al. (1995) and "Pervasive genetic hitchhiking and clonal interference in forty evolving yeast populations" by Lang et al. (2013) provided her with a framework for thinking about the competing stochastic and deterministic evolutionary forces that act on microbial populations at the genotypic and phenotypic levels to cause both parallelism and divergence under different scenarios.