REVERSIBLE POLYPLOIDY. “Thus, it is immediately apparent that polyploidy is, at least in part, reversible, and that over time it is followed by massive chromosomal rearrangements, reductions in chromosome number, and the large-scale loss of both repetitive sequences and duplicated genes all leading to genome downsizing.”
http://www.amjbot.org/content/early/2015/10/09/ajb.1500320