Evolutionary change within and between species arises gradually via the slow accumulation of mutations. However, large changes via so-called major transitions can give rise to fundamentally new forms of organismal complexity. Although phylogenetic tools can describe and predict evolutionary change, we lack a framework for experimentally understanding the evolution of the major transitions and how it remained robust in the face of parasitic cells. Using a combination of experimental evolution, synthetic biology and predictive mathematical modelling, I aim to tackle these unknowns, more specifically the initial steps from simple (single genome) to complex cells (multiple chromosomes). L-forms of Kitasatospora virdifaciens cells propagate without the cell wall, independent of the canonical cell division machinery and are unable to regulate chromosome number. Using this model system we will identify the mechanisms underlying the stability of chromosomal coexistence.
The project will be executed executed within the research groups of Alexander Kros, Daniel Rozen, and Dennis Claessen, Leiden University, and Hyun Youk, Technical University Delft. Shraddha Shitut is principal investigator.