PD position in Delft, Liedewij Laan lab: Predictability and reversibility of evolutionary trajectories

In previous experiments we have evolved nearly dead budding yeast cells (we removed a nearly essential gene) for one thousand generations. At the end of the evolution those cells approached wild-type growth rate and cell size. We sequenced the final time points and found three mutations that appeared in the same order in several independent lines, which is remarkable, since the vast majority of experimental evolution experiments do not show this high level of reproducibility.

In this project you will exploit this characterized system to ask questions about evolution, such as, how predictable is an evolutionary trajectory and how much does this depend on the specifics of the selection? Is adapting to genetic perturbations, like cancer cells do, intrinsically more predictable than adaptations to a new environment? Another potential question is: Can you ever go back in evolution or is evolution always irreversible? So what happens if you first delete a gene, adapt cells to higher fitness and subsequently reintroduce the gene and evolve the cells again? Are there regimes where the cells will evolve back to the original state? You will answer these questions using experimental evolution, whole genome sequencing and sequence analysis. The aim is to combine the experimental findings with population dynamics theory, potentially in collaboration with a theory group.  

For more information on this position, please check this webpage: To apply, please contact dr. Liedewij Laan:

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