yEvo: a modular eukaryotic genetics and evolution research experience for high school students

Abstract

Microbial experimental evolution paired with whole-genome sequencing allows researchers to observe evolutionary processes in real-time. The resources for carrying out and analyzing microbial evolution experiments have become more accessible. It is now possible to expand these studies beyond the research laboratory and into the classroom. We have developed a series of five connected and standards-aligned yeast evolution laboratory modules, called “yEvo,” for high school biology students. The modules have been designed to enable students to take agency in answering open-ended research questions. In Module 1, students evolve the baker’s yeast Saccharomyces cerevisiae to tolerate an over-the-counter antifungal drug, and in subsequent modules, investigate how evolved yeasts adapted to this stressful condition at both the phenotype and genotype levels. Pre- and post-surveys from 72 students at two different schools and one-on-one interviews with students and teachers were used to assess our program goals to iteratively improve these modules over three years. We also measured changes in student conceptions of mutation and evolution, confidence in scientific practices, and interest in STEM and biology careers. Students who participated in our experimental evolution module showed improvements in activity-specific concepts, including the importance of variation in evolution and the random nature of mutation. They additionally reported increased confidence in their ability to design a valid biology experiment. Student experimental data replicated literature findings on mechanisms of clotrimazole resistance and has led to new insights into this phenomenon. This collaborative endeavor will serve as a model for other university researchers and K-16 classrooms interested in engaging in open-ended research questions using yeast as a model system.

yEvo: experimental evolution in high school classrooms selects for novel mutations that impact clotrimazole resistance in Saccharomyces cerevisiae

“…Protocols for these experiments were developed in close collaboration with each teacher to best align with their time, resources, and learning objectives ( Fig. 1a ; Taylor 2022 ). Students used a simple serial transfer protocol to evolve yeast populations to grow in inhibitory concentrations of an over the counter antifungal, clotrimazole.…”

“…In addition to furthering our science research goals, student involvement advanced their understanding of how genotype and phenotype intersect, which is critical to understanding the process of evolution ( NRC 2012 ; NGSS Lead States 2013 ). We expand on our pedagogical goals and outcomes from this project in ( Taylor 2022 ).…”

“…The wealth of information available on azole resistance mechanisms and the possibility of identifying new resistance factors make this system particularly attractive for incorporating authentic research into a high school classroom. To leverage this, we developed protocols suitable for the experimental evolution of S. cerevisiae to select for azole resistance in high school classrooms as a course-based research experience called yEvo (available at yevo.org; Taylor 2022 ). These experiments utilized the drug clotrimazole, which can be found in over-the-counter antifungal treatments.…”

“…Our pedagogical aims and evaluation will be reported in detail elsewhere ( Taylor 2022 ). In this paper, we characterize 99 evolved clones from these experiments (performed by 203 students) using phenotyping assays and whole-genome sequencing.…”

Caffeine-tolerant mutations selected through an at-home yeast experimental evolution teaching lab

“…yEvo ("yeast Evolution") was developed as a curriculum for high school students to perform laboratory evolution experiments with Saccharomyces cerevisiae yeast in their classrooms (Taylor et al 2022a). We wanted to expand the curriculum to include other selective pressures and make the yEvo experiments safe and accessible to instructors and students in a variety of classrooms and for remote learning.…”