This dissertation consists of two distinct bodies of work. The first leverages a unique aspect of fire ant biology to investigate a potential role for a supergene in genetic assimilation. A supergene refers to a chromosome structural rearrangement, such as an inversion, that regulates the production of an alternative phenotype within a species. In fire ants, queens that carry the ancestral, non-inverted arrangement of the relevant chromosome exhibit plastic, environmentally induced phenotypes that resemble the phenotypes regulated genetically by the derived, inverted supergene. By comparing gene expression patterns associated with plasticity that associated with supergene-related genetic differences, I found evidence consistent with an evolutionary scenario where, via genetic assimilation, the fire ant supergene genetically fixed the production a phenotype ancestrally produced only as a plastic response to a certain set of environmental stimuli. This finding contributed to important goals in evolutionary biology related to unraveling the molecular basis of plastic traits, elucidating the genetic processes that sustain alternative phenotypes within species, and characterizing an evolutionary role of inversion-derived supergenes as a genomic architecture primed to facilitate genetic assimilation. The second body of work aims to improve undergraduate STEM education by characterizing variation and development of the knowledge teachers need to implement evidence-based instructional strategies in large enrollment classrooms. Over the course of several semesters, I interviewed early-career undergraduate STEM instructors before and after they taught the same focal lesson. Qualitative analysis of these interviews revealed variation in teachers’ knowledge of what students think about specific topics, how to teach those specific topics, and their general knowledge of how people learn. Longitudinal comparison of these interviews afforded insights into the patterns of knowledge development for these instructors and the instructional practice changes associated with knowledge development. Insights from this body of work can inform teaching professional development that aims to put early-career STEM instructors on the fast track to effective implementations of evidence-based teaching strategies.