Biology 173: Evolution of Yeast

Landscape of mutations during experimental evolution of yeast to extreme environments

Instructors: Prof. Timothy James & Prof. George Zhang

  • Section 004: Lecture (Friday 1:00pm – 2:00pm)
  • Section 301: Lab Wednesday 9:00am – 12:00pm
  • Section 302: Lab Wednesday 2:00pm – 5:00pm
  • Section 303: Lab Thursday 9:00 am – 12:00 pm
  • Section 304: Lab Thursday 2:00 pm – 5:00 pm


Applications for winter semester will open November 15th. Selection begins December 4th.

Note: Please submit only ONE application form no matter how many courses you are applying to. There is just one application link and you will be prompted to select all courses you wish to apply for and then rank your preferences. If you apply more than once, we will consider your most recent application as the valid one and disregard previous applications.

A mutation led to a population boom in one of 12 cultures, turning the medium turbid (third flask from left). Investigators can compare two strains’ fitness by culturing them together and then counting colonies (petri dish). One strain carries a mutation that makes its colonies red.” Image and text from “The Man Who Bottled Evolution” by Elizabeth Pennisi, Science 2013.

Populations are constantly evolving by changes in gene frequency that reflect adaptation to particular environments. Evolution is not solely a process that occurs over a long time period, but happens through small changes at the DNA level that can nonetheless make drastic differences to the population. In this course students will learn basic concepts in evolutionary biology through active research on evolving yeast populations in diverse environments. Students will research and learn about forces that dictate microevolution such as mutation, selection, and genetic drift. Students will perform a semester long experiment to adapt yeast to a variable environment by serial transfer of yeast cultures for 70 days.  To document genetic changes to the population, the evolved strains will be analyzed by genomic sequencing to identify mutations that occurred during the experiment, and these data will be used to perform a genetic modification to determine the effect of the mutation on the fitness of the yeast in that environment. Techniques and principles learned include understanding models of microbial growth, sterile technique, measuring relative fitness, genetic transformation, PCR, DNA sequencing, and bioinformatic analyses.