Section: New Results

Model of genome reduction

To test whether the effect of the rearrangement rate on genome size holds independently of the artificial chemistry of the aevol (individual-based) model, we have written a simpler, mathematical model of genome size evolution including both genes and intergenic sequences, evolving through small insertions and deletions, large deletions and duplications and through selection based on gene number. The approach was presented this summer as a poster at the SMBE conference (Society for Molecular Biology and Evolution). We have shown analytically that without selective pressure, genomes spontaneously shrink and that large genomes are particularly unstable. When selection is included that favors the highest gene number, simulations show that genome sizes do not grow indefinitely as large genomes cannot be sustained. There is a trade-off between fitness and structural stability. A manuscript is being written and will be submitted in January.