Does sex restrain genome evolution? An experimental investigation using yeast as a model organism

In sexual animals, chromosomes are organised in pairs, allowing allelic recombination during meiosis. During a previous international collaboration, Jean-François Flot and his colleagues sequenced and analysed the genome of the asexual rotifer Adineta vaga, a microscopic species comprising only females that reproduce clonally, without meiosis. They remarked that the chromosomes of these animals do not form pairs but display numerous rearrangements, similarly to stacks of playing cards being shuffled. This suggests that the loss of sexual reproduction freed the genome from the structural constraints imposed by meiosis, allowing it to evolve more freely.

To test this hypothesis, Jean-François Flot and his team will observe the evolution of the genome of beer yeasts (Saccharomyces cerevisiae, a model organism with a well-characterised genome) in parallel lineages reproducting either from time to time sexually or exclusively in a clonal fashion. In two years, the researcher hopes to see each lineage divide more than 8000 times, which corresponds to over 200,000 years of evolution when scaled to the human life. Changes in genome structure through time will be scrutinized using a cutting-edge technique called "3C-seq". The results from this study will allow us to better understand the role of sex in evolution.


FLOT Jean-François
Evolutionary Biology and Ecology
Faculty of Sciences

Created on August 31, 2018