Flowering plants recurrently undergo whole genome duplications, which in theory should create an increasing tendency of genome sizes. When looking at genome size distributions across more than 5,0000 taxa, the average genome size for polyploids remains constant at increasing ploidies. In the past this constancy has been attributed to a phenomenon called genome downsizing which in principle reduces the size of genomes. However, genome downsizing is not the only mechanism that could recreate the constancy in the polyploid genome sizes. I proposed different simulations that recreate this pattern assuming that large genome taxa, or taxa with large chromosome numbers are not undergoing or surviving whole genome duplications due to physiological, ecological, or maladaptive restrictions. With these simple simulations I estimated that we only expect from 0.3% to 17% genome downsizing when large genomes do not undergo or survive whole genome duplications, that is genome downsizing does not have to be large in order to maintain a constant genome despite multiple whole genome duplications.
The full article is published in the American Journal of Botany and can be found here.