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This geographic arrangement was what suggested the possibility of multiple origins to Ownbey. He and the Soltises have shown that to be the case. One of the polyploids has arisen 20 separate times, the other 13 – all within just 60 years.

Assuming that there is no genetic transfer (i.e., via pollen) between these geographically separate populations, I think the best "mechanistic" interpretation is that it's a complex example of "recessive" traits being expressed. These would be "throwback" cases, not "evolution."